Hi all.
Have a 07 klx250s with 9000mi. Did a valve inspection last month and all were tight, could not get smallest feeler guage in any. Reshimmed to get in spec. Starts right up and runs good except for a noticable ticking. What would cause this? Reset the cam chain tensioner twice, didn't notice any worn teeth. Thanks.

 

Smallest feeler gage? Like 0.002"? My guess is that you are hearing normal valve lash noise but not hearing it run I could be wrong. Even hearing it I could be wrong. With less than 0.002" clearance your valve train should have been very quiet so now you are hearing it. If you are worried pull the valve cover and check the new clearance. Maybe you made a math error, a measurement error, etc. If you are worried do the adjustment one step at a time with the forum group to offer guidance.

 

Sorry should have given better details. The exhaust measurements were .09 left .08 right. Intake measurements .07 left .06 right. Valve clearances exhaust .15-.24
Intake .10-.19 Exhaust shims were both 2.90mm. Intake shims were both 2.80mm.
Reshimmed with 2.70 all around. The ticking seems to come from the right side of the motor.

 

I believe strongly in the advice to go back to the last thing I did before problems started. You adjusted valve clearance last, I guess, revisit your clearance. But maybe first get some other people who know small thumpers to listen to your engine and advise. There may not be a problem.

 

Approximately how long have you run the engine since the adjustment? Has it just idled or have you ridden it?

 

What is on that side of the engine? The cam chain tensioner. Valve noise would be more prevalent on the left and center where the valves are closer to the outside of the engine.

I wouldn't say this if you hadn't mentioned the noise being from the right side. I'm not shilling tensioners, I'm pointing out what you already noticed and telling you the likely reason for it.

When the tensioner starts to fail the cam drive usually rattle at around 4000-6000 rpm, but if the tensioner is worn enough it can be heard over a wider range. If too much slack is allowed, it is possible to have the chain jump teeth at the crank with dire results. Takes a lot of wear to get there and the tensioner progressively fails. I have had a couple KLX300 riders actually snap chains when they jumped time. One bought the bike with the chain broken, fixed everything - but didn't replace the tensioner - ran the bike for a while and it snapped another chain. He hasn't had any problems since rebuilding the engine with a manual tensioner.

I would venture to say you do not notice the damaged teeth, it doesn't strike one as actual damage, kind of like how worn shifter dogs don't really look damaged, it looks like they're still there and functional, but polished slightly. But the lead tooth is rounded as will be the pawl, allowing the plunger to push back in, especially under deceleration, when there is tightening on the back side of the cam drive. The back side of the plunger will be polished where it repeatedly slides in and out.

Resetting will not help, the tensioner simply goes to the same place again and slips.

Two possibilities, one is to buy another OEM tensioner and hope it doesn't happen again, the other is to go with a manual tensioner and know it won't happen again.

These are magnified images of the tensioner from my 09 KLX250, 15,000 miles on the engine. Notice the eleventh tooth from the right, that is where the pawl hits when the chain is at proper adjustment. Under deceleration and also as the cams roll on and off the valves the plunger pushes back. As you see mine was pushing back around 10mm (.375") :