Jump to content
Sign in to follow this  

No compression!! Help please!

Recommended Posts

i have an 02 that one of the carb slide pins came out of and got sucked into the motor causing quite a mess. the machine shop cleaned up the head and luckily there was no damage at the valve seats just some pits in the dome. did a valve grind just to be sure.

we replaced the piston and rings and put it all back together but there was no compression whatsoever - 0. We tore it down again looking for a problem but cant seem to find anything out of place.

we are wondering if maybe it could be a problem with the auto decompression setup or maybe the shims need to be replaced now.... any ideas??

Thanks!

Share this post


Link to post
Share on other sites

A common mistake is the spark plug. Check it out, and let us know. Head gasket? ummm...that's all I can think of at the moment. Did you set the ring gaps? That too...

Share this post


Link to post
Share on other sites

If you had some shrapnel (pins) playing patty-cake between the piston and the head, there's a very good chance your valves are bent. When the head is off, simply pour some gasoline into the exhasut port and see if the valves are leaking. Do the same for the intake side. They should not leak at all if properly seated! This is my guess.....

Share this post


Link to post
Share on other sites

If the cam timing is wrong you can get no compression.

A good way to find the problem is with a cyl leakdown tester. They put compressed air in thru the spark plug hole. Its easy to hear if the air is going out the exhaust or intake ports or past the rings. If you get bubbles in the radiators then you've got a head gasket leak.

Share this post


Link to post
Share on other sites

You ground the valves? Then, yes you need to reshim.

Check the clearance.

Share this post


Link to post
Share on other sites

You ground the valves? Then, yes you need to reshim.

Check the clearance.

And if you ground the vavles, you'll need to reshim about everyother ride for about three rides, then you'll be out of space and have to pull the head off again.

The valves have a hard coating that when removed exposes the softer titainium to the valves seat face (which is harder than the hindges of hell)and will erode the valves in short order.

Good luck with that... :cry:

Share this post


Link to post
Share on other sites

hmmmmm. that dont sound like much fun. would it help to replace the valves as well? probably not cheap but if it would save me weeks of frustration then it may be worth it.

anybody know what valves cost?

Thanks for all the feedback.

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

Reply with:

Sign in to follow this  

×