Technical Column - Ask MX Tuner - - Dirtbike at Off-Road.com
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Technical Column - Ask MX Tuner

Source: Dirtbike at Off-Road.com
Ask MX Tuner

Mark is currently pursuing other endeavors, we hope to bring him back onboard soon. Until them - you can submit questions to the famous Rick "Super Hunky" Sieman, founding editor of Dirt Bike magazine.
His "Don't Ask!" column can be found at: http://www.off-road.com/dirtbike/columns/dntask/But don't say we didn't warn you!

Please feel free to check through Mark's back issues and technical articles below - someone else is bound to have had a similar problem to yours.
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Comments and Questions from our Readers
 Posted 2007-06-30 13:42:16.0
I was given a 87 TRX250X(to my knowlegde stock) that has been sitting approximately 3yrs. I cleaned the tank & carb, changed oil, spark plug,etc. I got it fired up and it will idle fine and it has decent accleration to about 20 mph but then seems to rev limit(pops and does not increase in speed). I have rebuilt & adjusted carb with no different results. Noone really wants to fool with it and I have been told that it could be the ignition module,stator,carberator,timing(which I have ruled-out timing). Is there a way to test these parts so I don't buy unnecessary parts. Could the main jet setting cause this and if so is there a more accurate way of setting than spark plug color? I hate to just trash the ol' girl but at the same time I don't want to sink a lot of money in to it. I have tried to find another one for parts but no such luck. I appreciate any advice.
 Posted 2007-07-12 12:33:28.0
um yea well iv had my 1994 kawi kx80 2 stroke for about 4 years and im to big for it now but im going to sell it but my problemis i recently changed the trans. oil and its not getting the power it use to i mean my dad rides it and he 300 lbs him sitting on the gas tank it rares up on him but not ne more can u recamend what kind of oil i should use or if thats not my problem then tell me what is
 Posted 2007-07-12 12:33:43.0
um yea well iv had my 1994 kawi kx80 2 stroke for about 4 years and im to big for it now but im going to sell it but my problemis i recently changed the trans. oil and its not getting the power it use to i mean my dad rides it and he 300 lbs him sitting on the gas tank it rares up on him but not ne more can u recamend what kind of oil i should use or if thats not my problem then tell me what is
 Posted 2007-07-27 01:24:16.0
hi i have a 91kx80 i have the top bolt and spring out but why wont theallen on the bottom coe out? please help
 Posted 2007-10-29 21:31:11.0
i just recently bought a used 89 kawasaki kd80x from a friend.i bought a brand new standard size piston and set of rings because it seemed that the standard size was still fitting pretty tight so i've been riding it for about a month and now it spitts and sputters and cuts out when you give it full throttle and alot of smoke starts to roll out of the muffler if you hold it like that long enough in second gear and all others above second.i've tryed cleaning the carb,new air filter changing plugs.i dont know whats going on it did run fine after the rebuild.do you know whats going on? Any ideals would be great,Thanks.
 Posted 2008-01-18 16:46:23.0
How do you go about bleeding the front brakes on a 1989 Honda CR 125? Any help would be greatly appreciated. Thanks
 Posted 2008-02-15 14:38:41.0
over the summer my 97kx100 the topend went so i had that put inan it needed cab adjustments andgot it stated i ode it 4 about 10 minutes an it bogged down anwouldnt start ne moe soi checked thereeds an they were junk so i replaced them i went to stat it after tht an the gas statedpouing out theoverflow and wouldnt start. any trips or ideas about whatswong or what i cando would be geatly appreciaed thanku Alex
 Posted 2008-02-19 22:04:12.0
I just finished my first 4-stroke overhaul and installed a new piston, rings, and cylinder, in my '03 YZF250. The bike started and runs great, but the exhaust pipe got "cherry red" in about a minute. Is this normal for a new or have I done something wrong. It has a ProCircut T-4 slip-on, but everything else is stock. Is this bike runnig lean and could it be due to a possible leak around the boot between the carb and the manifold/head? Thanks
 Posted 2008-05-19 14:02:44.0
Hello, Alright so heres the story Im 15 and have had many bikes already i purchased a 1987 yamaha yz125 for 850 dollars last summer. The bike appeared to be in good shape and ran when i bought it. Since i have had the bike ive ridden it and the situation is that the bike gets HOT and after riding for 15 minutes through trails it dies and im dead in the water for about 25 minutes then she will start back up.I have tried changing the spark plug to a new b9es and flushing the coolant and puttin better coolant in.Each radiator operates as it should i was thinking maybe because of going so slow on a trail the air could pass threw the radiators and cool them so it would overheat?Or the ratio? anything.. Now for the second issue when i bought my bike from the guy he told me the piston and rings were good and he ahdnt ridden it that much. I was wondering if i should be able to puch the kickstarter down with my hand with half of all my strength and have it give me alittle resistance. If so is that bad or good it hasnt fouled any plugs when i changed the plug it was tan and slightly black but not bad its always strated,still does. what would be the signs of a worn top end? and what would be a good ratio to run my bike at. thank you.
 Posted 2008-10-20 02:27:40.0
I just bought a 1986 YZ125 and it has rear drum brakes on it. I went to school for motorcycle mechanics so I could do the work myself, but is there a way to change the drum assembly over to a disc brake, or is it not worth it for the bike?
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