HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
gal

a disaster

7 posts in this topic

after i did my friend's 99 wr400 valve adjustment and changed to yz timing and replaced oil and oil filter - the bike started on the first kick. we went to ride, and rode for about 70km . we stoped for a short break and when we started to ride again after 10 seconds the rear wheel has been locked and the bike stoped. we checked oil and the oil stick gauge showed no oil . i emptyed the oil and i had all the oil inside , didnt loose anything - full.

i removed the valve cover and the cams and saw that the middle intake valve lifter is broken, i removed the head and saw that the piston n rings r ok but all the intake valves are bented. what could be the cause ? im sure i did everything by the manual but i didnt check the timing belt for being in the correct specs. and i didnt check the chain tensioner for being ok.

what do u reccomend to replace ? i thought of 3 new valves , one lifter and new timing chain and ,maqybe chain tensioner, a set of gaskets and im sure i will need a few new shims....

Share this post


Link to post
Share on other sites

How do you know all 3 intake valves are bent?if you are replacing valves,i recommend new valve seats and guides.i doubt theres anything wrong with timing chain or tensioner.you better check cam to see if its bent or any of lobes have worn flat.you are very lucky valve didnt drop into cyclinder and eat the piston and crank.when you switched your buddies timing from wr to yz did you also change jetting from wr to yz?

Share this post


Link to post
Share on other sites

I can't help wondering why no oil was showing on the dipstick. Did you verify that you had oil pressure after changing the oil by loosening the bolt on the oil pipe near the top of the head while it was running to see if oil was flowing? I'm wondering about what's going on with the oil pump. If it has debris in it, you could lunch your cases. It has happened to me.

When you say the "valve lifter" is broken, what do you mean? The "bucket", or is the cam is damaged? If the bucket was destroyed, what did it do to the head itself? There may be enough damage so that it doesn't move smoothly throughout the range of motion. That would suck because a new cylinder head would be in order.

You will definitely need a new head and base gasket. Your timing chain and tensioner should be just fine. I have a feeling that your valve guides are OK, too. The manual probably says to replace them if you get new valves, but unless they really got torqued, they are probably OK.

Hopefully, this is only a top end problem and you don't have to split the cases.

[ May 14, 2002: Message edited by: Rich in Orlando ]

Share this post


Link to post
Share on other sites

It does sound suspicious that the oil resovior in the frame was empty. This would suggest that the oil return pump wasn't doing its job for some reason. I would start by checking that pump carefully to see if you can figure out why it wasn't pumping oil back into the frame.

The second oil pump gets its oil from the frame, so if the frame is empty then no oil will be pumped to your head (or other places in the motor) and that could definitely make the valves hang open after a while without oil, in which case they would get hit by the piston and most likely bent. I'm guessing that the root cause was the oil return pump not working for some reason.

Share this post


Link to post
Share on other sites

when you were reassembling engine after timing and valve adjustment did you crazy glue or motor oil to lubricate valve train[buckets,cam,and cam bearings].i had a similar problem when i filled crankcase with 1600cc of superglue instead of yamalube.oh man,i could hardly kickstart the darn thing.

Share this post


Link to post
Share on other sites

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
Sign in to follow this  
Followers 0