top end noise

Ok so today I took the yz 400 to my xc race I pre ran the track 2 laps then shut it down till I was getting ready to race. O f you didnt read my post about the popping I have just re shimmed the valves on it. So I was riding to the starting line just idleing in first :p and the bike wasnt warmed up yet but it was warmed up enough to run off of choke and it stalls. I start it again and it now has a top end loud ticking sound on the left side. Needless to say I didnt race today:foul: . I have no Idea what it could be. I havnt opened it up yet but will tomorrow. Anyone have any ideas?

valves MIGHT have moved outa spec. idk, sorry but thats my only guess.

I would first check everything is timed right, marks line up, use screwdriver in sparkplug hole to find TDC, etc.

I would then check valve clearances, then loosen and re-torque the cam caps in a crisscross pattern in 3-4 increments down to the recommended torque per the manual (some say 75 in pounds which is alittle less). Then check the clearances again. If any different, maybe you didn't torque down the cam caps like this before, then it heated up and something loosened or expanded and then its out of spec.

If no different and clearances in spec, then maybe the cam chain needs replaced, if its loose, could've jumped a tooth that would be aparent with the timing mark check? Also if you took out the cam chain tensioner and reset it, maybe that is malfunctioning- you could pull it off and check its operation, but then might need a new gasket for it (that would be the last thing I would check).

Also make sure cam lobes are smooth/no marks from lack of oil at startup.

Can't think of anything else right now.

ok so I opened her up today and the intake had jumped a tooth. I re set it torqued the cap bolts down and installed another cam chain tensioner from another parts bike I have. I think the tensioner it had was working fine it was stock but the cap bolt on it had been stripped out (probably by me) so maybe some dirt and grit got in there and messed it up. Thats the only thing I can figure y this would have happened. What do yall think? Do yall think that was the noise I was hearing? I started it and it ran fine no noise

ok so I opened her up today and the intake had jumped a tooth. I re set it torqued the cap bolts down and installed another cam chain tensioner from another parts bike I have. I think the tensioner it had was working fine it was stock but the cap bolt on it had been stripped out (probably by me) so maybe some dirt and grit got in there and messed it up. Thats the only thing I can figure y this would have happened. What do yall think? Do yall think that was the noise I was hearing? I started it and it ran fine no noise

it probably wasnt the tensioner. But was the chain. The chains stretch and jump. Its been happening alot lately.

change the chain! i did mine for first time, wasnt easy but in about 1 hour of actual work it was done.

was realy hard to time it right and get the flywheel off, so i finishet it in more like 3 hours :p

lots of info on tt, use search.

If you going to change your cam chain most definitely, with out a doubt, get a flywheel puller. It's worth the 17 or so bucks for it. Trust me. :p

If you going to change your cam chain most definitely, with out a doubt, get a flywheel puller. It's worth the 17 or so bucks for it. Trust me. :p

yes +1 !!!

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now