I'm a 53 year old Dirt Biker that isn't quite ready to quit riding. I'm sure there are others out there, like myself, that are trail riding enthusiasts, that can't cope with the latest, high tech motocrossers. I can't, because the seat is so high that I can't get my leg over the thing! And once I do, I'm sit so high that my feet won't touch the ground. To avoid the above situation, I have ridden a personalized Honda XR 250 for several years. It isn't fast, but has a reasonable seat height, a smooth, broad power band and decent turning traits. With some work, the suspension can be made to work well. It doesn't require huge amounts of energy to ride the XR 250, so I can usually ride a complete day. (Still, I envy the younger riders on the motocrossers with the lighter weight (both bikes and bodies) long travel suspension and tons of power.) About a year ago, two of my younger riding buddies built bikes that utilized a CR 125 chassis and XR 200 engine.
That got me thinking. If a person stuffed an XR 250 engine into a CR 125 frame - that would be a neat toy for an old fart! (Maybe, it would give me a chance to go out and chase them young whippersnappers for a few more years.) I started scrounging and found an ad for a 90 CR 125 chassis in Cycle News. A few issues later, an ad for a XR 250 engine with a 280 kit was advertised and I answered the ad and bought the stuff. The chassis came from California and the engine came from Brown Brothers Racing in Washington. When the components arrived, my friends and I studied the engine and frame, did a little measuring and discovered everything would fit! But, we could see several problems that would have to be overcome. Fortunately, one of the guys that rides with us owns a machine shop and is an excellent welder. He had previously helped my buddies with their project bikes. The first big problem was the CR's front frame down tube. It interfered with the XR 250 engines dual exhaust pipes. This was solved by cutting the cradle out of the CR frame and replacing it with a cradle from an old TT 500 Yamaha. The next problem was carburetor clearance. This was solved with a frame modification that made it possible to utilize the CR's air box. The CR uses the swing arm bolt as a rear motor mount - the XR does not. Therefore, an aluminum spacer Getting adequate throw for the kick start arm involved building a right hand peg mount that allowed the kick arm to achieve a full stroke. The original right hand peg arrangement would only permit half the throw before the kick arm would hit the foot peg. The last major problem was the fuel tank. It was too long and hit the top of the engine. It had to be shortened considerably. After cutting, the tanks fuel capacity was reduced to 1.8 gallons. This is usually adequate because of the four strokes fuel efficiency. When I go on a really long ride, when fuel capacity could be a problem, I mount a two quart handle bar jug. We used the XR's wiring loom, electrical components and headlight assembly. All components work well. To enhance the performance, I installed larger diameter header pipes, a 34mm Mikuni carb and a Cobra aluminum exhaust system. The jetting is not "spot on" but I'm getting close. Right now, it has a #35 pilot and a 200 main jet at a 1700 feet elevation in Nebraska The clip is in the top position and the air screw is at 1 1/2 turns. The engine doesn't run really clean right off idle. However, it is crisp everywhere else. The bike weighs 230 pounds dry and has a 35 inch seat height. Does it work?
In impromptu drag races, (with me on board and out-weighing the competing rider by fifty pounds) it will out accelerate an '89 Kawasaki KDX 200 with an FMF pipe. It will stay close to a '95 Kawasaki KDX 200 that also runs with an FMF pipe. When the KDX's are topped out, the CRX can be shifted into 6th. I estimate the top speed will be 80+ m.p.h. with a 14/51 gearing combination. That's going to be a blast when we are fire roading in the Black Hill during the Sturgis Rally. The engine has a potent mid range. It feels like a baby XR 400. The CR's steering geometry gives it quick, precise handling. It carves through the trees like a super sharp knife through a thick beef roast! Most of the time, I'm a running a gear faster than I was on my XR 250. So, if you want a bike that's easy to ride and just plain fun, build one like it! Better yet, let Honda know that us "old" guys aren't dead yet... ...and tell them to build it for us! If you would like more detailed information, e-mail me! Jack Hixson or call: (402) 887-5380 A BIG thank you to Bill Nielsen, Steve Muessel and Ray Frish for their help on the project.
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