[Bill Marsh]

Please help. I bought a 2004 250x, It's last tune up and hours on the motor are not available. I bought it from a friend and it's had a few owner. The bike has been great for the last year and a half, it's a 250 w a big bore making it a 280.

Recently it starting making a clicking sound high up, I don't think it is a piston issue.

Oddly, the sound goes AWAY when the choke is pulled out.

Any thoughts would be greatly appreciated.

Bill

[JimDirt]

Welcome to the site !!

What it sounds like it could be is the Timing Chain is worn/stretched , or even a broken Timing Chain Tensioner

What you can do to test the chain is , on the bottom left(shifter) side of the cylinder is the Tensioner ... remove the center bolt (should be 8mm) , find a very narrow flat blade screwdriver that is short enough to get straight in there (eye glass screwdrivers work well for this) , put it in and move it slightly till you feel it go into the slot , turn it slightly and see if it springs back , if it does most likely the tensioner is ok (but not always as it could have tension from the chain itself pushing back) ...., now start the bike and insert the screwdriver and turn it each direction about 1/4 turn or less , listen to the engine , if the sound you have been hearing goes away or gets louder , then it is most likely a worn timing chain .....

There is also a slight possibility that the cam bearings are bad , or even the auto decompressor is the noise , but eliminate each thing before moving to the next ... report back with results ....

[Bill Marsh]

Thanks for the reply...I'll take your advice.

[Bill Marsh]

so would most riders agree it possible, probably isn't piston related?

[JimDirt]

Generally if it is a piston issue , you would have a compression or oiling issue , as well as possible metal/aluminum shavings in the filter and/or in the drain pan ..... can it have a piston issue ?? ... yes .... but I have run these engines for over 400 hours on the same piston without issues , sold the bike , and the kid that bought it is still riding it like crazy a year later , that was a 450R , my 450X is on the original piston and pushing 400 hours , and I would not hesitate to take it on a long trip in the back woods.... but engines revved to the moon and bouncing off the limiter , can last less than 50 hours ... but since it is a X , I would not think that to be the case of this bike being abused

Can a skirt break ?? , yea it happens , can a wrist pin seize up ??, yea , but that is usually accompanied by hard starting , stalling , heavy thumping sound , and then usually skirt breakage and seizure , and in a reasonably fast timeframe , so without those symptoms , I would be looking at the other things mentioned first , then if all else fails , then pull the top end and go from there ....

Hopefully some of the others will chime in and give their thoughts on this .....

Have you been able to confirm or eliminate the chain and tensioner and decompressor and cam bearings yet ??

[bigtoe250]

Hi JimDirt, my son is having the same issue with his 2005 crf 250x. Cam bearings are good, tensioner seems solid (but we will test while its running per your remarks above, no metal or aluminium in the oil or filter or screen, valve clearances were a little tight but not outta whack, and the timing marks line up so we will proceed with replacing the timing chain and reshiming the valves. Having trouble removing the flywheel nut so we bought an oil filter strap wrench and will try that this week.

Questions please:
* I am assuming the flywheel nut unscrews counter clockwise, yes or no?
* How do we check the counter balancer on the cam shaft? It moves easily, maybe too easily? Should it retract by itself?
* Do the chain guide and tensioner bar normally go bad? We will check those too.

Thank you for sharing your knowledge!

[bigtoe250]

* counterbalancer = auto decompressor. Sorry about that.