First off, this happened on an xr500. Even though this is an atv forum, I figured an engine is an engine. My friend let me borrow his 1980 xr500 dirt bike. The problem is, the auto-compression release is stuck open, so it has no compression. The lever going into the head is moving back and forth like it should be whenever I kick the pig over. I disconnected the cable that triggers the compression release, and it still has no compression
Does anyone know what could be causing the compression release to stick. I don't really feel like tearing the top-end apart, but i will if i have to. My friend is currently unaware of the problem and I would liked to get it fixed before i give it back.

Before I borrowed the dirt bike, it was run with no air filter, half of the needed oil that had the consistency of water, and the valves were never adjusted and the chain was never oiled. I have since changed the oil, oiled the chain, bought a filter, and was going to adjust the valves. The last thing I want to hear from him is that I didn't take care of the thing. If anyone could help me, I would be very greatful. Thank you for your time.

JaMeS

 

Hey James when you tear that mug down, call me up, a i can help.....beat the damn thang with a hammer it will fix it!!

 

if the rings were bad it would have smoked alot more that normal.... it could also be that the valves need to be ajusted or they are bad

 

my94blaster
thanks for replying. I'll try to fix the problem by tomorrow. I'll then go to your house and we can race. Too bad the xr tops out at 50MPH.


JaMeS

 

Surely this guy would'nt accuse anyone of not taking care of anything! Running that bike without an airfilter! why? I'm sure the top end is scratched up, no wonder it does'nt have compression. Next time if you know this in advance, DONT borough the dude's bike, you'll just end up with the responsibility of his junk.

 

I'm not familiar with this bike, but you should be able to check the compresion reliese by pulling the valve cover, not the head. If you pull the cover, you should find some type of devise that actually moves ehaust valve. Find out if it is stuck and try to clean/free it. But if it was run without an air filter, this may be the cause of the lack of compresion.

 

Thanks for replying biggerisbetter and knutz. The the last time i drove the dirt bike, it had very good compression. I parked it, then the next morning, it had very little compression.

When I tried to kick start it, it tried to break my leg and throw me over the handle bars. After that backfire, it wouldn't even sputter. When i checked the plug, it was fould out. So i know that either it is running rich or the rings are bad. I cleaned the plug, but it would still not even sputter.

P.S. The bike doesn't smoke at all when running, so I guess the rings are in ok shape??


JaMeS

 

Here's an update of the compression release problem.....IT WENT AWAY by itself. This piece of junk has a mind of its own. It decides when it wants to run like a champ and when it wants to kill me. It still won't start, but now it has alot of compression. It only sputters and backfires(not fun when kicking and it backfires) alot. The kid i borrowed it from wants it back so i am gonna give it to him and tell him it has not started in 3 weeks. Talk to you later.


JaMeS