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Mark Klein is
ready to answer your technical questions! Mark has extensive experience
race tuning off-road motorcycles for local and national races. If you
check back through our 1998/99 archives you will see a series called
"Dirtbikes 101." Mark brings his expertise to fielding your
maintenance and tuning questions.
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All Forked Up
I own a 96 KTM 360SX, and love it. Everything but the forks. As an
avid rider, I have many tastes and so far the entire bike has preformed
very well in all of them. But I have had an on going problem with
the forks. I have three sets of seals and bushings, along with
regularly changing the fluid and cleaning the wipers. As a Harley
Tech. I have little exposure to the ever changing market of MX.
All the local dealers and KTM owners that I have talked to have had
similar problems. Also I have progressed past the stock settings.
I am 6'3" and around 220lbs, and I over tax the suspension. I
have been able to get a heaver spring for the shock and it seams to work
wonderfully. I heard rumors of machining the forks to accept the
internals out of the newer CR forks. If this is true I have full
access to a decent machine shop. Your help is much appreciated and
needed.
The
KTM forks work fairly well once dialed in. One update KTM had with their
fork seals was to remove the spring inside the seal, unscrew the ends,
(one end is tapered and screws into the non-tapered end forming a
complete circle) and cut 4mm from the non-tapered end. This tightens the
new seal around the fork tube tighter. I've heard of guys doing this to
the dust seal spring also.
I'd
get springs that are rated for your weight and play with the oil weight
and level. Try 20wt oil in the compression leg set at 130mm. Use 10 wt
oil in the rebound leg set at the same height. This, combined with
stiffer springs should give a ride close enough that you can fine tune
it with the clickers.
MX
Tuner
My YZ Won't
Zing
I have a 1981 YZ-250. My problem is plug fouling and black goo being
expelled from the exhaust as well as leaking from the pipe after being
shut off. The bike generally starts on the second kick when cold (with
the choke on). If it stalls after riding for awhile (which it often
does) it can be difficult to start.
I carry extra
plugs just in case of fouling. There is also a very pronounced miss
during acceleration. When I parked the bike I noticed that fuel was
leaking from the overflow line. I have been using castrol 2 stroke in my
premix at 40:1 ratio. I suspect that perhaps the float needle is not
seating properly or the seat is loose. This could explain the leaking
from the overflow tube. Could this also be the cause of the fouling and
the black goo? I am going to try a synthetic premix oil as an option.
Could there be a possibility of a poor electrical connection or weak CDI
unit or coil.
Any help you could
offer will be appreciated.
Thanks, Tired of
Pushin
I
wouldn't try switching oils until you eliminate some other
possibilities. First of all, fix the carb issue. If it's dumping fuel
out the overflow hoses, the float isn't working properly for one reason
or another. Either the needle isn't seating properly or the level is set
wrong.
Once
you get that straightened out, repack the silencer. The packing will be
saturated and may be blown out anyways. Make sure the core holes are
clear and unobstructed. Don't pack the silencer too tightly. The packing
has to absorb pressure pulses to work correctly.
Unless
you're running at wide open RPMs 95% of the time, you can benefit from
running a spark plug one heat range hotter than stock. Run a BR8ES plug.
This should help reduce the spooge coming from the exhaust.
Any
corrosion on an electrical component or connector can give some erratic
running symptoms. Make sure the ground points are also clean. A chipped
reed petal can give some unusual symptoms also. Don't forget to check
these basics.
MX
Tuner
Shiftless Bayou
2001 Kawasaki Bayou 220, auto transmission, 5 speed with reverse, 2
wheel drive. When shifting from first to second gear, the foot shifter
is so tight it doesn't want to go into second gear until after 2 or 3
HARD tries. This happens when going up hill, but more so when going down
a hill in first gear and needing to change to second. This has been
happening almost since after buying new. Your help would be so greatly
appreciated.
Thanks, Emily
Sounds
like the auto clutch mechanism isn't releasing fully. This would be the
same symptom as a manual clutch not releasing or dragging. I'm not
familiar with that particular auto clutch but I'm assuming there is an
adjustment somewhere, maybe inside the motor. Sounds like it's time to
take it back to the dealer for a minor adjustment.
MX
Tuner
Ellisnor...
I have resently purchased a 1981 cr125r ellisnor. The used bike dealer
assures me that there was a new wiseco piston in the machine and had
under 30 hours on it . I rode the bike for 4 hours and oil mixture water
in the rad levels are all fine but as i pulled up to my trailer i shut
off the bike and now it won't kick over. the bump starting wont
even budge the transmission allows gear changing and it seems the piston
is seized my question is are there any special proceedures to rebuilding
a top end or tips you can provide me with . I have overhauled car
engines how would 2 strokes differ??
Two
strokes are similar from the standpoint they have a piston, rings and
connecting rod. The similarities end there, though. Two strokes have a
slew of differences from the intake system to the exhaust system.
Getting a good manual will be invaluable and the first step in this
learning process you're attempting. It isn't rocket science but there
are steps that should not be overlooked. A good manual (try ordering the
Honda manual from the Honda dealer) should give all the info you
require.
MX
Tuner
XR650L
Compression
Dear Mr. Klein, I own a 1994 Honda XR650L, which I have modified
quite a bit:
Among others, the
engine has just been rebuilt using a 101mm 10,5:1 JE forged piston, and
a White Brothers 1652 all around camshaft. The cylinder head has been
treated for better gas flow. The feeding is taken care of by a flatslide
41mm Keihin FCR carb with an accelerator pump breathing through a
K&N filter. Exhaust gases leave through an XR's Only oversized set
of headers mated to an Arrow tailpiece. I am currently in the process of
running it in. I ride it at slow speeds and varying, low rpms
(2-3000rpms, using my ear; my ear hasn't failed me in the last 12 years
I've been riding motorcycles).
The problem I am
having is that the engine occasionally pings (self-detonates) at the rpm
range I rev it (2-3000rpm). And this isn't because I have it in the
wrong (high) gear.
I have tried using
the "super"-98 octane unleaded we have here in Greece. This
eliminates the detonation in all occasions except when I open the
throttle very suddenly. In this case, it pings for a fraction of a
second and then in clears. Can it be that the compression is too high?
All associated
literature claims that the piston and camshaft combination I am using is
a very popular and safe mod. Are they wrong?
Is it that I may
be using bad quality fuel? I'm buying gas from well-established firms
such as BP, Shell etc. I use the bike for my everyday transport as well
as racing (enduro and supermotard) and I want to avoid using
aviation/racing fuel or fuel additives.
Any advice? I
thank you for your time and help
Best regards,
Manos/Greece
I'm
not familiar with the quality of fuel you have in Europe. It is entirely
possible that the ping is due to a lean fuel/air mixture in the lower
circuits in the carb. Try richening the mixture with either the low
speed fuel screw (this screw is very sensitive to adjustments-1/4 turn
is a substantial change) or with a richer pilot jet. Even if the carb
was jetted fo your individual application, the list of mods you give is
fairly intense. It can be hard to anticipate your jetting needs.
The
other possibility is you need higher-octane fuel than you can buy at the
gas station. You may be able to get by with adding a little octane
booster when you fill up the tank.
MX
Tuner
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Performance
Mods - YZ250F
Hi-there... Your website it?s beeing seen in Portugal! Congratulations!
I Race in one
YZ250F 2001 and I Would like to know if you have any recomendation to
improve my bike (If it?s Possible).
Thanks in advance,
Chico
I've
built a couple big bore motors with the 250F. Going to a 2mm bigger
piston helps immeasurably. This requires having the cylinder bored and
replated. Wiseco makes a piston and Cometic makes the oversized gasket
kit. Compression is raised to 13.5:1 so you'll have to run race fuel.
The big bore motor has a BIG improvement in midrange and top end power
over the stock motor. I've heard nothing but good things about the Dr.D
pipe for the 250F. The stock exhaust is a bit restrictive at higher rpms.
The
suspension can be fine tuned to your weight and riding style. This can
be done with different spring rates, fork oil height, and a number of
other adjustments. Your owners manual will cover a lot of these fairly
thoroughly. Getting the suspension revalved for your weight and skill
level will help quite a bit.
Tire
choice is a critical area for performance. I know way too many guys who
choose a tire that isn't for the terrain they are riding on and suffer
the poor results because of it. Good tires are well worth the expense.
MX
Tuner
KX Kakked
I have a 2000 KX250 I bought a couple of months ago. The bike has
run perfectly until now. A couple of weeks ago I did about 80
miles of trail riding on it and it ran perfect. A few days ago I
brought it to the track and the bike started up fine but when I took off
on it I noticed it had very little power and then a few seconds later it
killed. I pulled the spark plug out and it was a little wet, so I
poped another plug in. It started up again and ran for about 5
seconds and killed again and wouldn't restart. I took the plug out
and it didn't look very wet, so I wiped it off and put it back in and it
did the same thing as before. The bike has an aftermarket pipe and
aftermarket reed valve on it. The previous owner jetted the bike
to run with these modifications, and it ran great, but it was a little
on the rich side. I pulled the carburetor off and the insides were
clean, and I saw no point in changing the jetting since it worked fine
before. I also pulled the silencer off and checked the packing. It
was in pretty bad shape so I replaced it but this didn't help. The
piston and rings have about 20 hours on them, and I'm running a premium
synthetic oil at 32:1 with the stock spark plug. Any suggestions
on what to check next.
Thanks, Michael
Baton Rouge, LA.
My
next step would be to inspect the reeds. Some of the aftermarket reeds
are made of carbon fiber. Some of these carbon reeds have a relatively
short life span. The reed petals can chip or fray. If this is happening,
it can give the exact symptoms you are having.
Either
that or you may have a problem with the carb. A thorough cleaning (this
means all the passages in the carb body and all the jets) might be in
order.
MX
Tuner
Dragging Clutch
I have 1996 Suzuki RM 125 with a dragging clutch. I had local
dealer install new clutch plates. Complete with fibers, steels and new
springs. The clutch still drags. I have adjusted it with little or
no free play and it still drags. The local dealer disassembled and
reassembled it 3 times. They even called Suzuki factory support
technician. We still have not been able to figure out the problem. Would
appreciate any information you could give us.
Thanks, Vern
I've
run into this before on the mid 90's RM 125s. I got a significant
improvement by adding a shim under the release bearing under the
pressure plate. One other possibility I thought of since (and haven't
had the chance to try yet) is the clutch springs are coil binding. In
other words, the clutch plate can't move fully because the springs are
compressed to the point the coils are touching each other. Adding a flat
washer under each spring screw can add to the total height of each
spring screw casting. The outer diameter of the washers has to be
smaller than the inner diameter of the springs. This will release some
of the spring tension on the springs but will also allow the pressure
plate to move farther from the clutch hub, reducing the amount of drag.
Like
I said, this is something I thought of but have not had the opportunity
to try. If you try this and it helps, please let me know.
MX
Tuner
Jetting With PC
Pipe
Hello, I have a 01 yz 250 stock accept for a pc spark arrestor. Stock
pipe. After I put on the spark arrestor I have black goo coming out the
pipe. Pro circuit said to jet at 175 main, 2nd clip on the needle and a
45 pilot. I still have black goo coming out. Any suggestions? The bike
runs great though. I run 92 gas with Maxima super m at 32 to 1. I there
a better oil and ratio?
Thanks, Mark
First
of all, don't trust PC's jetting recommendations. Your local conditions
can vary too much. A 175 main sounds too rich. The Super M is a great
oil lubrication-wise. But it is a very dirty burning oil. I'd stick with
a proven oil like Yamalube 2R or Honda HP2. Both are synthetic blends
and are among the best oils available.
Let's
see... spark arrestor. So you're riding it in the woods. There is
no way you can run the bike hard enough to use the stock plug. You need
to go at least one step hotter. I'd use a BR7ES. This will cut down on
the spooge significantly.
MX
Tuner
Black Goo
Hi. I have a 2001 KX 125 that I bought brand new back in early October
2000. When I first got the bike, I was running the recommended 32:1 gas
and oil mixture. I had a problem fouling plugs after about an hour of
riding time. I bumped the mixture up to 40:1 (Leaner on the oil side,
but richer on the gas side) using Castor 927. That took care of the
problem as far as the plugs go. But I am still blowing a black
sticky residue (which I assume is oil) out of the silencer. This is very
annoying especially when its all over the swingarm, and rear caliper.
The bike is bone stock, and doesn't have many hours on it at all. The
problem isn't as bad as it was when I was running 32:1, but its still a
problem in my book! I was going to try and maybe drop the clip position
on the needle 1 clip size; I have been told that it will help, but I
figured I would check with you guys first. Any info you can give me will
be greatly appreciated. Thanks!!
Greg
You're
on the right track. You definitely need to lean the jetting. Start with
the pilot jet, though, not the needle position. Try Eric Gorrs website
for a good jetting guide. Go to www.eric-gorr.com
for more info on that.
The
927 is a castor based oil. Very good for lubrication but bad for oily
residue. If there weren't any good lubricating oils available, I'd
recommend it but there are way too many good choices to need to put up
with the residue.
MX
Tuner
I have a 2001
CR125R and I have problems starting when the engine is cold.
- I just rebuilt
the top end, I replaced the cylinder rings and gaskets. The cylinder
look like it was in good condition, physically. I replaced the ring
because it looked like I was getting blow-by. There was a normal
amount of carbon build up on the piston top. This cleaned right up
using a little two stroke boat decarbonizer.
- The stock reeds
look like carbon fiber. They look fine. There is no gap between the
cage and the reed.
- The carb is
clean, I have the stock #380 jet installed.
- I am using a
new plug that produces spark when touched to the outside of the
cylinder.
The only way I
have been able to start it when cold is to use starting fluid shot past
the air filter. Once the engine has warmed it starts fine, first
kick. Then engine runs fine, plenty of power.
Do you have any
suggestions as to what I can test next?
Thank you for your
time!!!
Sounds
like the choke circuit in the carb isn't working correctly. Either
that or the float level is set too low. I'd go through the carb and look
closely at all the adjustments. Check both sides of the float when you
check the float level. I've seen one side check fine and the other be
off significantly, all this from the factory.
MX
Tuner
XR or KLX -
That Is The Question?
Hi, I am torn apart by these two bikes. The XR has a name and
I want it. However the KLX is more updated (liquid cooling,etc.).
I don't know which one to choose. I am looking at the 250cc model
for both of them early 90's I hope. My question is:what should I
look out for whne buying an early 90's model of one of these. What
were some common problems of these bikes. I am going to be doing
mostly trail riding and a little MX. What are some cheap mods I
could do to beef both bikes up a bit. And I have read many letters
of yours and understand that the XR is not a MX bike, but hey there have
got to be some good mods out there. Thanks a whole lot for your
time.
Tyler
Neither
one is a bike made for motocross. A good friend of mine broke a KLX in
half riding it on a motocross track. That isn't saying the KLX isn't a
durable bike. The KLX is an excellent bike but it just isn't made for
motocross. Neither is the XR. Neither one has suspension suited for
jumping at all. Both can be modified but the results are marginal.
Thumper Racing makes a slew of hop up parts for the XR and the KLX but
all that comes at a price. Four stroke motor mods are generally much
more expensive than a two stroke.
Both
bikes have their shortcomings but those are small in comparison to
making sure the bike you're looking at is in good condition
mechanically. That can be far more costly rather than a few relatively
small problems both bikes have.
MX
Tuner
YZ 125, Yamaha
1996
I bought my dirt bike used so i dont know what is up with the top
end. I scraped it a little bit so I brought it to a yamaha dealer. I
thought that all I had to do was bore it out and get a new piston
and that was all. But instead he said i couldnt bore out my tope
end because it was nickel plated. I was just wonder if it was the
stock material or nickel plated would it be able to be bored out?
I already sent it in but was wondering if it was the wrong thing
to do if it was able to just get bored and adn get a new piston. I
would have saved a lot of money. I know for sure that I did not have a
sleeve because it was all one piece so it was either the stock material
or nickel plated like he said. thank you for your help.
Peter
Your
YZ has a plated cylinder from the factory. If it gets damaged, you can
have it replated the stock piston size. You can also bore the cylinder
and have it replated to the larger size. Going 2mm bigger would result
in a significant increase in power over the entire rev range. This is a
common mod used in race bikes. Some people recommend a steel sleeve but
I just haven't seen any benefits of doing that. It is more costly and
needs to be bored later in life when a plated cylinder won't unless some
damage occurs.
MX
Tuner
Honda - Baja
250 (aka Super XR250)
Hi Mark - I've got this steering wobbling problem whenever I travel
on/off-road at high speed. But the problem reduce whenever I carry
pillion or let go one hand (on road). However, I've tried lowering my
rear height and even softening the rear suspension which of course
affects the race sag but still in vain. Hope you could advise on this.
Thanks!
KT - 21.09.2001
I
wonder if your fork springs are too soft. This would contribute to the
symptoms you're describing. You may be able to use preload spacers to
help reduce the front dropping too much. But this would be an attempt at
curing the symptom instead of the problem. Stiffer springs would most
likely be the correct way to fix this.
MX
Tuner
CR500 Parts
Swapping...
Mark, first of all let me say what a great column you have and how
much I appreciate the fact that someone like you would share your
knowledge with such patience. I have a 85 CR500 which has several mods
but the ignition is stock and I have a Coil and CDI box off of an 87
CR500, that I know is good, can I swap out the Coil and CDI box on the
85 with the 87? I know that the Coil mounts differently but I
think I can over come that. My main concern is that the bike runs
great up to high RPM and then it's starts to break up (my guess is the
CDI or Coil). I know that high RPM is a nebulas statement and most
of my friends who ride the bike never notice it because they never push
it that hard. I have a freshly packed silencer and a
"works" pipe, jetted the pilot and main, changed the clip
position and turned the choke idle screw all the way in and the bike is
crisp and only loads up after 30 min or so in tight woods (I'm a little
afraid to jet it down anymore and I run a 14oz flywheel weight) it will
clear right out after about 1/2 mile on a straight away. I
run Yamalube 2R at 32:1 with Amoco 92 octane fuel and am thinking about
changing the pipe to a FMF or Dyno Port?
Thanks for taking
the time to read this....
Highest Regards,
Andy
The
deciding factor for the ignition swap would be the connector where the
stator plugs into the CDI harness. If they plug together, you'll be
okay. I'd be a bit surprised if they didn't, giving the somewhat subdued
nature of open class development over the years.
Make
sure the reeds are in good condition. You still may be a bit rich across
the board with the jetting. A crisp running 500 should be able to run in
the woods continually and never load up. You might consider a spark plug
one step hotter.
MX
Tuner
Beer or XR200?
I recently purchased a 1984 xr200..the price a 30-pack of beer.
The bike ran when I bought it but was in dire need of a new head gasket.
I am having that repaired but am interested in finding out if this bike
is worth dumping any money into. I know that 1984 was one of the
years that honda had produced this bike with dual carbs......I'm just
not sure if this is a good thing or a bad thing. I would greatly
appreciate if you were able to send me some info on the type of bike
that I bought and if it was worth the 30-pack of beer. Thank you
in advance!!!
Dave
The
dual carb XR wasn't a bad thing, just difficult to get right if someone
screwed with the linkage adjustment between the carbs. They weren't
supposed to open at the exact same time. Actually, it was a pretty good
bike. Just don't expect too much out of it since it is, after all, 18
years old.
You
ask if it is worth dumping any money in to. It depends on how much you
have to dump into it, how much work it needs.
MX
Tuner
Suspension Dial
In
I just bought a 2002 honda cr250. i weigh 135.
i am unsure as to
where i should set my suspension at. i mainly ride at my home.
it is a supercross-style track. doubles, flat landing jumps,
whoops, and bumpy straight a ways. i have about ten hours on
the bike. i change the fork compression about 7-8 clicks softer than
stock; the fork rebound is about 5 clicks softer than stock;
the rear shock high speed is about 1/2 turn softer than stock;
the low speed is about 7-8 clicks softer than stock. and the
rebound is 6-7 clicks softer than stock; and the spring is at
stock setting. my back is still hurting, but not as bad as the
first ride. on a flat landing, or sloped with front and rear
hitting at the same time, the bike kicks up a bit; enough to jump
my feet off the pegs. I was also wondering about what oil i should use?
we have used Pennzoil for the past few years on 98 cr125's.
my dad has this thing about new bikes and using hp2 oil @ $6 a
pint. i also heard that valvoline make a two-stroke oil now.
You
need to go on a triple cheeseburger diet. Backing out on the compression
adjusters is a good step in the right direction but I wouldn't back out
on the rebound. They need to be close to the stock settings to prevent
bad things from happening. You really need softer springs, front and
rear. At least set the rear spring sag for your weight, or as close as
you can get it.
Your
owners manual goes into detail about how to set that. Do one slight
variation, though. When they say to take a measurement with you sitting
on the bike, do it standing on the pegs instead of sitting down. This
will eliminate a big variable of where you sit on the seat. Plus, you
never sit in the same place when you're on the track anyways. Once you
get the spring softened, it should give a more compliant ride. Put the
rebound clickers back to the stock setting and adjust the compression
clickers to your preference.
Personally,
I have to side with your dad on the Honda HP2 oil. That is one of the
best oils around at any price.
MX
Tuner
Comment
On This Article
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It's a Gusher!
Hi, i have a 1994 RM 80, it has a racing carb and every time i switch
the fuel on it gushes out of the overflow pipe at the bottom and right
hand side of the carburettor. ive had the carb in bits and clean it out
not just before this problem occured do you think i damaged something
while doing this? any help would be brilliant! thanks a lot! p.s great
website.
Chris
The
float needle isn't shutting off the fuel flow properly. It may be that
the floats are installed incorrectly. Even if the carb is assembled
right, the float needle and seat may need replacing to get the fuel flow
to stop.
MX
Tuner
Seized RM -
Broken Ankle
My son rides a 2000 rm-125.We found one in new cond. and,after
riding,decided it was jetted too rich (smoked alot,black plug).It had
the stock main jet(175) so I went to a 170.He rode the next day and said
it ran better.I checked the plug and it was still black.The following
day,while skimming thru whoops ,the damn thing seized and spit him
off.He ended up with a broken ankle.
We used gas from
the same jug as the day before.This bike has maybe 15 hrs on it.I can't
understand how this happened.Any thoughts are appreciated.
Jerry
The
seizure may or may not be related to your rejetting. When rejetting a
carb, it is necessary to start with the lower speed circuits first and
move your way up the throttle opening scale. In other words, start with
the pilot jet/air screw setting. Once you have that leaned out
sufficiently, move to the needle position. Then go to the main jet. You
could put a 120 main jet in and it won't help a rich condition on the
pilot circuit.
MX
Tuner
Y C YZ Leakage
I recently bought a 86 YZ125 off a friend of mine knowing that the
top-end was most likely ready to go. It was still running but no
compression to speak of. In to the shop, new piston rings and a 1x-over
on a cylinder that I was suprised to see that was still at stock piston
size. I just got it back yesterday when we start it up ojn its virgin
run. Seeing an excess amount of casing oil coming out the overflow we
think the shop guy filled it a little heavy, so we kill it then kick it
over again, bingo no more oil. Bringing it home I kick it over again and
damned if its not intermittenly spittin out up to 1-oz of oil. Im
thinking the shop guy bombed, and maybe the rings arnt sittin right,
getting blow-bye in the top end, also oil is coming out the tail pipe.
other then that the bike is a beast at top end and sounds great.
The
gearbox and the crankcase are two separate sections that should not be
affected by each other. The crankcase has the fuel/air mixture flowing
around the crankshaft and going up through the transfer ports in the
cylinder to the combustion chamber on top of the piston. There is an oil
seal at each end of the crankshaft. The left seal prevents air from
entering, which can create a lean running condition. The right side seal
prevents gear oil from entering, which can create an excessive amount of
spooge from the silencer and also oil foul spark plugs, not to mention
make a lot of white smoke from the exhaust.
The
oil drooling from the transmission overflow hose is most likely due to
an overfull transmission. Chances are the top end work is unrelated.
MX
Tuner
Noisy CR
I own a 1988 Honda cr 125. This is my first two stroke bike.
It was in very nice condition when I bought it, the bike was in storage
for a three years without being started. I have been riding it on
and off for about 2 years. I have been gearing and tuning it up
for mountain trail rides. This year I have noticed it makes engine
noises louder then the newer bikes. Noise really only is heard
when idling. It sounds like gear lash or something like a skate
board going down the street! I have change the clutch plates with
steel. Also I had found that the water pump had corroded through the
case. I had to use JB weld to repair the hole and replaced the
impeller. I had the top end rebuilt with using a wisco
piston. I was wondering what am I hearing and what is the
acceptable noise level for that year of bike. I have change the
transmission oil often to review any metal in the oil. So far,
no major signs in the oil, just the black gray color. The bike really
has not been rode alot but stored most of its life. Could it have
a bearing starting to go out in the case due to the long storage?
Matt
It
is relatively common for some noise to come from the clutch area. As the
clutch basket bearings and races wear, they can get loose enough to
generate noise. I doubt if it has anything to do with sitting for a long
time, since a lot of newer bikes make a similar noise fairly soon.
MX
Tuner
Low Compression
I have a 2001 xr250r that seems to have lost compression. I removed the
head and jug and checked the rings and cylinder. both aren't showing
excessive signs of ware. when I replaced everything IM not sure that I
got the timing correct. but if I didn't get I correct I still don't
think I have allot of compression. ive even tried kicking it with the
decompression cable disconnected. please help. also is there a company
that makes a repair manual for such a new bike. thank you for your time,
william
You
may have made the same mistake I have made before. Under the cam, there
is a spring-loaded pin that engages with the auto compression mechanism
on the cam. This pin has to be in place for the auto comp release to
work properly. On the motor I built, the pin had fallen out when I had
it upside down and I didn't catch it. You should be able to see this pin
through the right side intake-valve adjuster-cap without having to
remove the entire head cover.
I'd
order a manual from Honda.
MX
Tuner
All Wet...
Please help! I just got a new 2002 kx 125 kawasaki. (4days old)
The dealer put some gas in it at the store with the oil mixture on the
rich side. I understand why. This is for the breakin period. It ran
alright for a little while, then it started to foul the plugs. I
expected this. But now we that we put in the proper 32:1 gas mix (kawasaki
2 cycle oil) we cannot get the thing running without taking the plug out
and drying it out. When it starts it will only run for 10 seconds and
dies. I remove the plug and it is wet. Have good spark. Is this oil any
good, it looks nasty to me. Thanks!
Aarons dad.
I
doubt if the oil is your problem. I don't know anyone who uses Kawasaki
oil, but I don't think that's your problem. Sounds like it is running
way too rich. It is most likely too rich jetting-wise but even that
shouldn't make it only run for 10 seconds. I'd look closely at the carb
and the float level or float operation. Is there any fuel leaking out
the carb overflow hoses?
One
other possibility is they may have put a different oil in it at the
dealer that isn't compatible with the Kawasaki oil. They may have poured
from the wrong gas can. The only way to be certain is to drain the fuel
tank and carb completely and start with something you're more
comfortable with. I'd shy away from castor-based oils. Yamalube 2R is
very good oil, as is Golden Spectro or Honda HP2.
MX
Tuner
Clutch
Action...
I have a 2000 CR 250. I didn't like the clutch at all when I first
bought it. It was far too stiff. Now it totally sucks. I
have oiled it and adjusted it. Now it doesn't disengage at all. What can
I do to get my clutch (1) to work (2) to work so smoothe that I can
operate the lever with 1 or 2 fingers. Wow! Talk about arm pump!
You
may have some galling occurring at the end of the clutch pushrod where
the actuating arm pushes it. But try a couple other things first. Get a
new cable. The stock CR cable from Honda should be fine. If you don't
have a pressure cable luber, buy one. They are well worth the $15
investment. Lube the new cable with either WD 40 or Tri-Flow. Don't use
anything other than these. Tri-Flow is better since it has Teflon in it.
Now get some clean grease (wheel bearing grease is ideal) and lubricate
the barrel end of the cable where it goes in the lever. If the cable end
has a plastic sheath or a sheet metal end over the lead barrel, get as
much grease as possible under there. This HAS to slide as the lever is
pulled. Now put a big glob of grease in the hole the cable goes into and
also a little in the pivot bolt hole. Greasing these two holes can make
a big difference in the effort required to pull the lever.
If
this doesn't give the lever pull smoother than a new CR, you may have
the galling on the pushrod end. You'll have to remove the clutch
pressure plate to remove the rod to inspect it.
MX
Tuner
Dragging DT
I have a 1977 Yamaha DT 250. 3800 miles and all stock. My problem is
that it won't run smoothly through the rpm range. It seems to really
miss at 3000 rpm. It runs okay for a couple of minutes when it's cold
then gets worse. It is running rich with a lot of oil coming out of the
pipe. I have replaced points and plug, jetted down and up and tried
changing the needle positions. Nothing seems to help. I have taken it to
local shops but they don't have any luck. Any Ideas? Thanks, Ron
I'd
start by replacing the right side crankshaft seal. Sounds like you're
motor is sucking the gear oil into the bottom end and burning it.
MX
Tuner
Noisy KTM 520
Hi, I have just sold my 2001Honda XR400 and got a new 2002 KTM 520 EXC.
The XR400 had a
very smooth sounding engine, but 1st time i started the engine on the
KTM I instantly noticed the engine had a very definate rattle to it
while it was idling in neutral. The rattle almost completely dissapears
when i pull in the clutch lever.
the rattle is also
very noticeable when riding at low engine speeds. The dealer i bought
the bike from said the noise was completely normal, but i was looking
for a second opinion. Do KTM's usually have a rattly sounding
engine?
Any help would be
appreciated
Thanks, Alan.
The
KTM is a race bike that wasn't designed to be quiet running like your XR
was. The noise you describe sounds like a relatively normal clutch
noise. Some bikes make it more than others. A clutch has to have a
certain amount of movement between components to work. As long as your
dealer is aware of the noise, I wouldn't do anything more than keep tabs
on it to make certain it doesn't get worse. Keep that oil changed
frequently. Big difference in the service intervals between the 520 and
your old 400.
MX
Tuner
Loosey Goosey Honda
CR 500, 1986.
Hi Mark and thanks for the previous help. Well heres my new problem. I
just finished rebuilding my 86. I notice that my shifter has about
1" of in and out play. I don't remember it being that loose when I
tore it down. I've checked everything ( tore it down again ) and I can't
find anything wrong. On the right side cover there is a cast in rib that
looks like its supposed to keep the shifter from moving in and out too
much. Is this wore down? If so is there an easy fix, like inserting a
bolt in the end of the shifter shaft to take up the play? I don't want
to fire it up with this much play, it looks like it may tear up new
Boyseen ignition cover. Any ideas?
Scott
There
may be a white nylon collar that goes between the center case and the
shifter shaft mechanism. If this collar is missing, the shaft will move
in and out abnormally. I can't see the side cover wearing that much. I'd
look closely at a parts diagram and see if there isn't a spacer collar
gone.
MX
Tuner
KX 500
Burbling!
I have 85 KX 500 and it always seems to blow blue smoke. It
starts right up all the time and idles perfect. But in the mid
range it starts to smoke. When I get into 4th & 5th
it runs really good(mostly wide open). I have changed main
jets, clip positions, and still will not run right. The bike I can
no longer get parts for (discontinued). I had the brass arm that
shuts off fuel break and I could not get the part. I had to
find one that fit. I found one from another carb and it
works. Also when I rebuilt the motor I notice that the head
was very thin as if someone milled a few times! The
compression on this bike is amazing! Could the head be a major
factor or the carb? Could it only be that the bike is for
race gas? Or it will make it run richer?
Thanks DJ
For
carb parts, you might be better off getting a new, more modern
carburetor from Sudco or Carb Parts Warehouse. Sounds like your pilot
jet is too rich. Changing the main jet just isn't going to help lower
throttle setting jetting issues. The main jet only begins to come into
play over half throttle.
If
the head has been milled, you may have to run race fuel. I'd check the
compression and compare it with what the manual recommends. If it is too
high, you might try stacking base gaskets to lower the compression. This
would be cheaper than buying a new head. This will raise the port timing
slightly which will ease the bottom end a little also. This can help
make it easier to ride.
MX
Tuner
Bogging 50
Dear MX Tuner - My son has a Husqvarna 50cc Sr.. Husqvarna has
replaced the coil stater three times and this last time they replaced
the fly wheel and the coils stater. it just dosen't seem to be
running right. Sounds like it is bogging down and someone said
that it could be the timing, the jet or the front end needing to be
rebuilt. We would like to be able to maintenance the bike ourself.
How do you adjust the timing? I don't even know what question to
ask about the jet. Surely it wouldn't be the front end - he got it
last Christmas and has not ridden it that much. He has a Yamaha that he
races too. Also, is their a manual that would help us with these
problems?
Thank you. Karen
Husqvarna
should be able to supply some sort of manual for your 50. This should
give any info concerning changing the timing. The timing is adjusted by
rotating the stator plate but timing too far advanced can result in a
motor that burns holes in pistons. I think whoever said the "front
end" needs rebuilding probably meant the "top end". I
doubt if this is the problem. Chances are repacking the silencer and
rejetting the carb will help with the bog. Eric Gorr has a good two
stroke jetting guide on his website. Go to www.eric-gorr.com
for more info.
MX
Tuner
1982 Kawasaki
KDX 175
When the bike runs, it runs very well. It burns clean, has excellent
throttle response, and good power through the entire throttle range.
There are no out of place noises or odors. The trouble is, it doesn't
run very often. Even when it does run, it is impossible to kick start.
It needs to be push started. After a couple seconds of dead revolutions,
it will finally come to life, if it is going to start at all. Once
started, there is no certainty as to how long it will continue to run. I
believe the problem to be eletrical. When it doesn't start, the plug is
wet and I can not get it to spark after it has been removed. The coil
tested good. I can measure a voltage from the stator and ignitor, but I
do not have a repair manual and have no idea what the voltmeter is
telling me. I bought the bike used and every wire has been spliced. I
have traced all of the wiring, removing the excess, and insured there
are no shorts. It is obvious that the engine has been apart and the wear
on the screws suggests that the stator and ignitor are not original and
have been removed several times. I can find a stator but have been
unable to find an ignitor. Is there anything else I can do or is it time
to buy another bike?
A
service manual will give resistance readings to check the ignition
components. You might try cleaning all the grounding points for the
whole system. Corrosion or paint under a mounting tab can give some
erratic symptoms. Just look where the coil mounts and any ground wires.
MX
Tuner
Sprocket
Selection
Hello Mark, I have a new Honda XR650L and I am a beginer at off road
riding. I bought the L so I could ride up the street to get to the
trails. I don't like the way the motorcycle is geared. Where
I ride and starting out slowly I don't use anything beyond second, and
when I am in the slow stuff I'm usually sliding the clutch in first. I
realize the top speed of this motorcycle is at least 70 mph and I don't
ever expect to go than fast on or off road. Could you give some
basic guidelines on making a sprocket slection. I looked at the
specs for some other Honda models and see they use other ratios. I
would like to just change the front sprocket because of cost and wrench
time. Also this model uses a one piece chain so how does dropping
a couple of teeth off the front sprocket affect chain adjustment.
As for the parts is this a dealer only item. Any help would be
appreciated.
Thanks, Rusty
Gentry
Sunstar
and Renthal both list a 14-tooth sprocket available to replace the stock
15 tooth. Sprockets are not a dealer only item. This will give a
substantial lowering of the gearing. This should be able to be adjusted
without cutting the chain provided the chain isn't too stretched. Even
with the lower gearing, your 650 should still do well over 70mph.
MX
Tuner
Clutch Slip
Have a 1999 KX500. Clutch is slipping but only when I run the bike for a
few hours. The bike is tuned and hopped up to the limit pushing 75+
horsepower. I inadvertently dumped Belray gear saver 80W in the tranny
which is for my friends bike. I should have been using something like 30
or 40W. Have I caused the problem? Am I doomed? I pulled the drain plug
last night and left it out. I am thinking if I just let it drain a few
days and put the correct oil in I should be okay? Or, do I need to pull
the cases off and clean/replace the discs?
I appreciate the
advice.
Sincerely, Stupid
KX500 Rider
You
should be fine by using your favorite oil. You might have to drain it
after a few minutes to restore your original clutch action. I've found
Type F automatic transmission fluid works very well, especially for KX
clutches. It actually improves their feel. The ATF provides excellent
lubrication protection and helps shifting also. I'd change it every few
hours, regardless what you use.
MX
Tuner
Comment
On This Article
(http://www.off-road.com/dirtbike/columns/mx/2001nov.html)
Bog Standard -
1991 CR250
Not so much a problem. I just need a bit more power to keep up with my
mates XR600! The engine is in mint condition and is pretty fast as it
hasn't done much for a 10 year old bike. All I have ever done is replace
the piston rings about 4 years ago as a precaution and put in a
Multi-Air air filter. I think the first step is an FMF Fatty pipe and
carbon reeds(or perhaps a rad valve?). And perhaps get the barrel tuned
for more top end as it is very torquey. Is this the best way to go? I
have also seen some companies advertise big bore kits to 265, 285 and
even 300cc. Is this a good idea and would it be relaible? Your
opinion would be much appreciated.
Thanks, Alan.
Some
of the big bore kits can reduce reliability and increase vibration if
you go too big. The 2mm over kits are great. That would be the 265cc
motor. Those help more than you'd think 2mm would. Eric Gorr is the
master at doing these. He'll also port the cylinder for your personal
preference at a bargain price. His work is second-to-none. Go to www.eric-gorr.com
for more info. Another very cost effective mod is a Delta V-Force reed
cage. Once jetted with the new reed, you'll be quite surprised at the
improvements they make. The stock Honda pipe is really pretty good. An
FMF pipe will help it rev higher.
I'd
replace the piston. 4 years is about 2 years too long to go for a bike
that is casually ridden.
MX
Tuner
Beached XR
I have a Honda XR400R 1997 model which I am having difficulties with.
Following a beach
run, which involved sea water crossings, the bike back-fired and would
not restart.
I have since
managed to start the bike however it only runs for a short time
(APPROXIMATELY 5 - 10 MINUTES).It then back - fires and will not
restart.
I have completed a
number of routine checks which have proved unsuccessful in finding the
route of the problems. i.e.air filter, carburettor, and spark plug. I
did locate oil in the left hand side casing cover which contains the
rotor and stator coils. I would be grateful if you could assist with the
following questions:
a) Should there be
oil within the casing cover described?
b) If not - could
this be the cause of the problems I am experiencing?
c) Do you have any
other suggestions as to the source of the problem?
I look forward to
your reply and would like to thank you for your assistance.
Yours in
anticipation
Scott
The
oil around the stator is normal. Sounds like you have some water that
got into an electrical connector somewhere and has corroded causing an
open circuit somewhere. You say "sea water". I take it this
means salt water. This is very corrosive. Definitely check any and
all electrical connections.
MX
Tuner
2001 CR500 -
Piston Slap?
i bought bike brandnew,cant have more than 5-6 hours on it,broke in
very easy,still has good comprision,starts very easy, seams to run great
slow or fast,will ideal just fine,no noticeable runing
problems..BUT,,when cold or hot,when i rock bike back&forth in
gear,has loud piston slap type noise so i took off pipe and with
fingers in port i can move piston back and forth what feals like
20 thou of an inch or what feals like half width of the ring,,i
think clearance should be 4 thou of an inch.please help,could the
factory have over bored it or to small a piston..p.s. any input
would be appreciated
I'm
a little unclear which way you're moving the piston to get it to move.
If it isn't making noise when it is running, I wouldn't worry about it.
You may be hearing the chain slapping the swing arm.
MX
Tuner
1997 KX125 Carb
Tuning
I am having trouble with my bottom end acceleration. I Bought this bike
from a gut that lives at 11,500 ft elevation, I live at 5,000 ft. It had
a 155 main jet in it, boy did that spit oil all over the place! I
replaced it with a 145 but kept fouling plugs. I finally replaced
the jet with a 140, seems to have worked so far. The biggest
problem now is bottom end acceleration. That bike runs like a
raped ape at top end, but I have to stay on the gas all the time
to get any power. I was reading about the slow jet, but can't seem to
get enough information to convince me. I need to know if a different
slow jet will help and if so, what size do I need? Got any ideas?
Convincing?
Your bike doesn't run right and you need convincing? With the 140 main
jet, you're going to nuke your top end. You need to go closer to stock
and rejet the pilot (slow) jet. Try www.eric-gorr.com
for a good two stroke-tuning guide.
MX
Tuner
Overheating
Sorry if this is the wrong place to send this. I have a 98 rm 125
that keeps overheating. It will send coolant pouring out of the
overflow in the neck of the radiator. one
persone told me I was running too lean so I raised the needle
valve up, it is now in the second from bottom clip. I have
the air screw out 1 1/2 turns. The stock jets are still in it.
I just recently put my stock pipe back on due to damage to my FMF fatty
pipe. I also just recently put boyeson reed valves in, replacing
the stock reeds. two times now I have had to replace head
O-rings empty all the water out of my pipe. LOL I replaced
my radiator cap with one off of a kx60 after the first set of
melted head O-rings. Why a kx60? It is all I had on hand. I
just switched from Klotz r-50 pre to castor 927. Could any of
these changes be the problem? Or someway combine to be?
Could you e-mail me back if you can, Thanks
Randy in Dublin,
VA
The
Castor 927 isn't the cause of your problem but I wouldn't suggest
running it unless you plan to rebuild your top end once a month to
remove the residue build up. Chances are your head is warped. You
can true it with a piece of emery paper taped to a flat surface (piece
of glass or marble). Spray the emery paper with WD 40 and start rubbing
the head in a figure 8 pattern. Run it over the emery paper a few
minutes and clean it off. You can see the pattern where it is touching
the emery paper and where it isn't. Continue until it has touched across
the entire head surface. Oh, and get the correct radiator cap unless you
have a specific reason to run a different one.
MX
Tuner
Oil Seal
Replacement How To
rm400 suzuki early model air cooled. i, need to know if i need to split
the cases to replace the oil seal's on the crank shaft or what????
I
don't know. A service manual will provide you with all kinds of good
info.
MX
Tuner
Bottomless
CR480
I am a long time rider at 33 years of age. My dirt bike is the 1983
Honda CR480R. It is in very good condition for being 18 years old. My
question is about gearing ratio's on this bike. The drive sprocket is a
14, and i changed the rear from a 54 stock to a 46. That means a ratio
jump of .259 to .304. My concern is the long term affects on this older
Elsinor engine. Its a big jump and i was just concerned about
"stressing" the engine (air cooled)....What do you think ???
My main reason for
changing the gearing was to make second gear faster for tracks. I am
usually doing alot of shifting between 2nd and 3rd because once yer in
power band then there is no top end power AT ALL. and second gear always
seemed a little slow for me. Attached is a pic from S.I.R (Seattle
International Raceway) in july of this year.
Any help would be
appreciated,
Jim
The
motor will handle the gearing change just fine. I think I might look a
little closer as to getting more top-end out if it maybe. The 480's I
remember had plenty of top-end.
MX
Tuner
Burning
theTranny Oil
I have a 1974 Yamaha D/T 175-A. It is burning the oil out of the
tansmission. what is causing this to do this? what parts do I need to
fix it ? Thanks for your help Ray
It's
either your right side crank seal or the center case gasket. My money is
the right side crank seal. You should be able to get by with a right
side cover gasket and the new seal unless you open a can of proverbial
worms.
MX
Tuner
2001 Yamaha
YZ125
Problem: Black oily residue coming out of the end of the silencer
and dripping all over the swingarm and bottom side of silencer. Gas/Oil
mixture I am running is 1 bottle(pint) Yamalube 2YR racing oil to 5
gallons of premium gas (40:1)
Performance:
Bike runs very strong and does not blubber. Plug is slightly dark like
it is a little rich.
Corrective actions
taken so far:
- I have moved
the needle jet clip up one notch from the middle setting in order to
lean it out slightly.
- Backed the idle
air screw out slightly.
Results: Bike
still runs strong but no difference in oily residue on bottom of
silencer.
Would appreciate
any ideas on what may be causing it and additional things to try.
Mark
Your
low speed jetting is too rich. Lean the pilot jet a step or two should
help significantly. Also, unless you're truly running extended high RPMs
continually, you'll benefit from running a BR8ES.
MX
Tuner
Comment
On This Article
(http://www.off-road.com/dirtbike/columns/mx/2001nov.html)
Failed Water
Pump
I have a 1996 KTM 300 EXC. It has a Boyesen Reed assembly and a FMF
Knarly pipe w/and Answer silencer/Spark arrester but is otherwise stock.
I love the bike but on my last ride the water pump seal went bad and
loaded my bottom end with coolant. I did not notice it until the
overflow tube spewed oil/coolant all over the engine. The engine
showed no signs of overheating from a riding stand point even though I
rode many miles with no coolant and a tranny full of oil/coolant.
My question(s):
- Other than
replacing the water pump seal is there anything else I should look
for in the way of damage?
- In a KTM 2
stroke what type and weight oil should I use in the tranny?
- Do you have any
jetting suggestions for slow riding trails at 3,000 to 5,000
feet el. in N. Ca. as currently it drools alot out of the tailpipe?
- What coolant
should I be using? Thanks for your help
The
clutch plates could fail due to the coolant. The coolant can actually
dissolve the glue that holds the fiber to the plate. This is usually
after being run for a long time (much more than an afternoon). If it
isn't running poorly, I wouldn't tear into it. It'll most certainly let
you know when the top end is damaged.
You
can use just about any 10w40, 15w50 motor oil, 80w90 gear oil,
motorcycle specific gear lube or Type F ATF in your gearbox. Personally,
I'd use Mobil 1 15w50 synthetic motor oil in your KTM.
The
stock pipe had a problem with the stock 360 exhaust having too small a
diameter at the pipe where it goes into the silencer. Dyno-Port made an
excellent pipe and silencer, which made the bike much easier to rejet.
Plus, the first 360's had a cylinder head that was updated right after
production began. So, the first 360's would benefit greatly from
installing the updated head. Check with your local KTM dealer for the
casting marks to identify which head you have.
I've
never had any issues running standard automotive coolant. If you have a
bike that runs hotter than it should, and has trouble overheating, you
might want to consider running Red Line Water Wetter or Engine Ice
coolant. But for all other bikes, I'd recommend Prestone Low-Tox. This
is the "pet safe" anti-freeze/coolant. Most conventional
coolant is ethylene glycol. Low-Tox is propylene glycol; the same stuff
Amsoil sells for $25 a gallon as high performance coolant. Good stuff.
MX
Tuner
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