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Hand filing shims in Baja and other lessons...

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Hi all,

Learned a lesson in baja last week and thought I'd share. Saturday while the 1000 is finishing up we are getting started on a 4 day moto ride, I'm waiting at San Matias while a few class 11's and a BC car race by trying to beat the time cut-offs as the wife and friends cruise up and her 250x isn't starting. Put her on the XR400 (rock you know what solid) and load it up and head to Mikes Sky Rancho. Beers and the best 3/8" steak around were had. Then more beers.

The morning comes around and the right side intake shim is tight. I brought tools, feelers but no shims. The leatherman wave was brought out and we started filing, still no clearance so we keep filing. We get clearance to .005 and call it good. As I mostly know the XR400 and you can pull off the entire cam chain tensioner and we didn't have a small enough flat screwdriver to pull back the spring I took it all the way off. Replaced the tensioner evenly screwing it in put her together and was ready to go!

Way too hard to kick and the starter could barely turn it over, stripped it down again, still has clearance so tried again but no luck. We finished our trip trading the xr, made it to the pacific and back. Great trip overall and was looking for head rebuilding services as our next race is in 2 weeks. Found a post about the tensioner being a problem, pulled it out today and twisted the spring and reinstalled it and she fired right back up!

I know a valve job is in the near future but the tensioner was our problem and we should have fun at the race coming up. And YES, you can file down shims in a pinch at Mikes Sky Rancho and keep riding!!

Thanks for reading and I hope it helps someone sometime!

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Sounds like you made the best of the situation. Thats probably one of the worst times or places to find out a valve is failing and to have problems getting it to start!

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As soon as you remove the cam chain tensioner from the cylinder, it will automatically push out and lock in the fully extended position, till you retract it with a screw driver.

For example; say the total travel of the adjuster is one inch, say that it was operating at 1/2 inch of travel to provide the correct cam chain tension before you messed with it. When you removed it, it extended and locked, at one inch out (it is an automatic tensioner, it will automatically extend till it is opposed by the cam chain tension, then it will not retract past that point, unless manually retracted with a screwdriver).

When you forced the fully extended adjuster assembly back into the cylinder using the two mounting bolts. This put massive force on the cam chain!!

This huge tension forced the cam chain down in the bearings and pulled the crankshaft up against it's bearings. Result? tons of friction!! The cam and crank are tied together and pulled towards each other by the now waaayyy too tight cam chain, the motor is locked up and it will not start.

Solution? follow the directions!!

use a little screw driver to release tension on the automatic tensioner before you install it, once installed, release the tension. The tensioner will automatically extend till it sets the correct cam chain tension.

This is a very simple and well designed system, you do not need many tools to shim a Honda Motor, it can easily be done, even on the side of the trail in Baja!! (I have done it myself!)

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fast idles with choke on OK ? clogged pilot jet would be my guess

dude i cant get my 04 250x to stay idle

ive taken it in and it works for a bit but damn its drivin me nuts,.. any solutions???

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