ticking xr400 engine top end ticking

[mikemoosemattia]

Hi there, i got me a problem. my xr400, about a week ago i heard a slight ticking in the right hand side of the head, the sound kept getting louder as i rode the bike to and from work. i figured it was the valves. so when it got loud enough to hear without listening for it i went in and checked valves for the first time in my life. did a fair job. in spec now. but as i didnt know much as it was my first time, in all my wisdom i turned the flywheel clockwise trying to find tdc. (Which isnt where it should be, not on the T marker) i heard a clicking/snapping noise when i did this, ive read now that it could have been the manual decomp? but now the noise is so loud its almost drowning out the idle. i checked the cam chain tensioner. its fully extended itself. is this my problem? or did i break something?

[Trailryder42]

The click sound sound when turning the crank clockwise most likely was the auto decomp.. Always turn the crank counter clockwise only. It has to be at TDC on the "compression" stroke. You know you're on the compression stroke when you can reach thru all 4 caps and feel wiggle in each sub rocker. If you end up on the wrong stroke, you have to go around CCW 1 more time. If the crank slips past the T mark, do not back up CW. Doing that can activate the auto decomp and throw off the right exhaust valve measurement and adjustment. Go around 2 more times back to TDC on the compression stroke.

Taking the spark plug out helps to keep the crank from shooting past TDC. If you adjusted the valves on the exhaust stroke, they're all set wrong. You'll know if you adjusted them on the exhaust stroke if when you measured the clearances they were out of spec by more than a couple thousandths and they took quite a bit of adjustment to get to spec.

What year model is your XR?

Be sure you DO NOT turn the crank while the cam chain tensioner is out.

Test the tensioner to be sure it still functions properly by inserting a screwdriver in the center. Turn to retract the plunger and make sure it extends back out on its own. If you can fully insert the tensioner with it completely extended, your cam chain wear is beyond what the tensioner can compensate for. Time to think about a new chain.

[mikemoosemattia]

Its a 2002 model. it starts and runs, im assuming that means the timing is fine, But the incredibly loud ticking is worrying me, im not riding it like this, thankfully im not that clueless. but the manual decomp still works. i can feel a huge difference when i kick it over with it pulled or with it not pulled, i should probably mention that on one of the strokes (probably compression stroke now that i think about it) theres so much compression i cant physically kick the bike over, its like stepping on a brick! This bike is offroad plated and i plan to trade it to a buddy for his road plated XR. I just want to make sure i dont give him a bike thats going to cost a ton to fix. just want to know what i could possibly do to resolve the incisive ticking noise. 

Being mechanically inclined must be nice LOL.

Edited May 1, 2017 by mikemoosemattia

[Cole Way]

Try adjusting the valves. It's really easy there are tons of videos on YouTube. Just make sure you have the engine at top dead center (tdc) before adjusting

[Trailryder42]

Ticking from the right side of the head is most likely the right exhaust. It's easy to get wrong, as it's the one the manual decomp system activates. With the engine at TDC, you have to check/verify that the manual decomp lever on the handlebars has at least 1/4" slack in lever travel, as measured at its tip, before you feel it engage the valve. Have to verify it's right before you adjust and make sure it's right after making any adjustment to the valve clearance.

If I were you I'd pull the valve caps again, set the engine to TDC on the comp stroke and verify what I described above and verify that the right exhaust valve clearance is set to .005" (.12mm)

Edited May 1, 2017 by Trailryder42