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XR 200 project


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Think they will work ? I have to shim the eyelets some they are a hare thin but other than that they fit fine , it was the only reasonable thing I could find in the same length that was on it. The forks are next ,I'll post those when I get parts to put back together.

This bike was built by someone who new what they wanted Fork tubes by Frank, aluminum swing arm and aftermarket exhaust along with 79 cr 125 fork lowers / front wheel and some odd trees that are Honda but old. Who know's but maybe a cool trail bike.

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I still have two pairs of Curnutts in different lengths and travel. Long ago I went to a stacked spring set so that I could have a nylon separator ring between them to slide on the shock body. It eliminates the Curnutt

"squeaking" as the spring rubs the body. Some of the later shocks used a teflon type of body coating but that would eventually wear off. Still loved the long travel in the days when everyone else was Short Strokin' it!

Flip your springs over by the way. The close winds close first and they should be sprung weight at the frame not unsprung at the wheel end.

LONG time since I had a twin shock XR200 though, early '80s.

ScF-200.jpg

This was my XR200 in my early 125 custom frame with the XR200 forks and Curnutt shocks. 176lbs w/oil-no gas. A LOT of fun and street legal.

Swiss

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Good catch on the springs I will turn those over. I want to use these springs if possible if not I guess dual springs may not be hard to find. Should I put a teflon spacer at the bottom against the stop? Any help with this is appereciated I'm in deep on this one.

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No the Curnutts never used bottoming bumpers or cones.

They were designed by Charles to use full travel with hydraulic cushion at the end of travel. Using the long springs you will need to spray them lightly with a lube Dry Silicone may work well and they will squeak for you a little. Enjoy.

Swiss

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It has been a few years since I used Curnutt shocks but aren't they suppose to be mounted shaft up? My recollection is there is a washer that floats on the shaft and acts like a check valve to increase rebound damping, on rebound it rests against the piston and covers some holes, on compression oil flow pushes it away from the piston to uncover more holes for oil flow. If the shock is mounted rod down the washer will settle down to the seal head and be ineffective.

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I have no idea - but if that is the case I have the springs upside down. See post above and let me know what you think. I'm a week or two from getting swing arm parts to assemble but these shocks are worrying me.

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Ok I turned the spring upside down that's easy to unwind, I made spacers and bushings to fit the upper and lower mounts which are different that was a pain. So do I need to put the aluminum collar down , rod up with the close winds at the top ? The shock seems to sound and feel different - better when the rod is up. Also I cannot find bushings is ok to use high strength hyd hose ? seems to be the only thing I can find that will fit. Thanks again for you help I'm in this pile and will not give up.

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No, the "early" Curnutts were mounted with the shafts up but Charles then changed the design and switched the mounting with the shaft down.

I had one pair of the early shocks and then later got two pairs of the inverted shocks.

What you have done looks fine.

Swiss

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Nice looking project. Some good ideas there. It should be a excellent bike when done.

Curnutt's are old school, but still pretty good shocks and rebuild-able when you blow a seal or need different viscosity fluid in them. Boge/Mulholland's are probably a bit better, then the spendy Works units.

I raced with these Curnutt's this weekend at Mid-Ohio.

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Fork tubes are 35 mm and have FRANK stamped on the top. The springs are larger diameter than stock and the sliders and trees are 77-79 cr from the best I can tell. It has air valves - old style but they should be good.

The question is how much and what fork oil, I have read 10 oz of 10 wt may be a good starting point, also to fill to 5.5" below top and 3-4 PSI added slowly yo the valves. Any help would be great. Looks good like this maybe a decent set up.

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IMG]http://i1036.photobucket.com/albums/a442/shawntex_2010/IMG_0441.jpg[/img]

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I have the forks assembled.

They are 35 mm tubes-FRANK'S in 77 -78 CR125 sliders the springs are large diameter and slightly longer than stock. I replaced the piston seal, tube seals, clips , and hardware. All seems fine no friction or sticking with assembly oil.

I compressed them and added 5.75 oz of 10w to each one and this seems too little.

I cannot find any info stamped on the forks or anywhere else. Any ideas or suggestions would be great.

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It came on the bike and I have not seen another one - I suspect it came from a so cal mx shop that used to make all kinds of aluminum swing arms before they were on all bikes form the factory. The name escapes me.

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Frank's was an aftermarket company that made replacement steel fork tubes for both street and dirt bikes. Evidently the tubes on that fork were shot and replaced. I think the stock tubes are better than the Franks's but they are also more expensive.

There was also a Frank's Racing which was around in the late '70s that ran some CR bikes and such. Remote possibility that these are from them.

Swiss

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  • 2 weeks later...

81-83 XR200R forks are 35mm and have 10" of travel, XR185/200 twin shock forks are also 35mm but will have less travel. Pull the triple and check the bearing sizes, if both bearings are 26x47 there will be a lot of Honda forks to choose from. There are a bunch of mini-bike forks that are 35mm and some of the later models had a disc brake.

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