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

 

If the compression release is working properly then the next most likely problem area would be the piston/rings/cylinder. If the bike has been run without an air filter like you say, then it's pretty likely that the piston and rings are worn from dirt entering the cylinder. Running the bike without the air filter could also create a really lean condition which could have added to the problem. I would start by removing the valve cover to check that the compression release is functional, and that there are not any stuck valves. If that checks out then I would tear down the top end.

 

yambike.....thanks for replying. I don't think the piston or rings are worn because it had alot of compression the day before the release stopped working. This problem has bappened before except that the compression release was stuck so it was not working at all. I weigh about 155lbs and I could just barely kick it over. It finally broke loose and was working fine for a month, then the current problem arose.


Thanks again for replying.


JaMeS

 

From the way you describe it "breaking loose" are you positive that the engine didnt seize? Sometimes you can break lose a seized engine but after that its all borrowed time. Good luck

 

MNWildFan as far as i know the engine was never seized. By "breaking loose" I meant that the compression release started working like it should. Before, it was not releasing the compression like it should have and it was a pain to kick over.

Thanks for replying.

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

 

disconnect it from the head, the cable, it may have rusted and when u ride it comes loose again. it thats the case, replace the release cable, or work out and get a little stronger in the legs,(lol)
good luck

<< when in doubt,,,,,,,,,........................gas it! >>

 

foneguy......The first thing i did was disconnect the cable. I can kick it over just fine, my problem is the dirt bike likes to kick back. when the 500 kicks back, it does it with authority. I usually end up with a huge welt on my leg when my foot slips off the kick starter, or it catapults me onto the bars and I fall over. The bike is going back to it's owner tuesday.


JaMeS