Removed Top End (PICS)

[95formula847]

I removed the top end of my 91 KX500 after i was getting warm compressions of 75psi. Here are pics of what it all looks like. let me know what you guys think.
















None of this has been cleaned up. Everything is in the same condition as when i first pulled it off. The piston looks very clean to me. Is this from running lean? The plug chart tells me my plug reads rich running. Also could the 75 psi of compression cause the bike not to idle? I tried two different compression testers and got the same results. One of which is calibrated every month at the aircraft maintenance shop i work at.

Also are these bikes sleeved from the factory? Because my jug looks sleeved. There are a few grooves in the cylinder walls so if it is in fact sleeved... is the fix just to bore it alittle and run a slightly oversized piston. I looked the part number on the piston up and found it was a standard sized wiseco pro lite. It seams to be in ok shape but i will buy a piston kit none the less. The rings were very loose and could be removed easily with one finger from the piston. Thanks

[kaw rider]

2 year ago a got bad set of rings that didn't seal, low compression. installed new rings and then i had normal compression.

I would install rings into bore and check ring end gap and see what kind of tension you have. That sleeve looks very glossy.

[stewart]

no there not sleeved from the factory  ,,,that cylinder is sleeved..how much water did you burn that will make the parts look clean like the that chamber does may be a leaking fiber head gasket  just one possabilty

[95formula847]

in 16-18 hours of riding i didnt burn even a drop of coolant. My radiator was filled to the brim the day i bought the bike with clean green coolant. Everytime i rode i checked it and it was filled to the brim.... nice a green colored still. Im 100% sure it didnt burn any coolant.

[stewart]

thats good you checked it i have seen coolant do that

[95formula847]

ya i like to check over my bike alot cause i have pretty bad luck when it comes to things breaking

edit:

i took the cylinder in just now to the local dirtbike shop. The cylinder is gettin bored and they are ordering a new piston kit for me. should be back together next week

[ID KX500]

ya i like to check over my bike alot cause i have pretty bad luck when it comes to things breaking

edit:

i took the cylinder in just now to the local dirtbike shop. The cylinder is gettin bored and they are ordering a new piston kit for me. should be back together next week

What no windowed piston? I strongly recommend it if you aren't.

[95formula847]

what do you mean by windowed piston? do you have a part number?

[ID KX500]

what do you mean by windowed piston? do you have a part number?

http://www.kxriders.com/forums/index.php/topic,5681.msg43394.html#msg43394

[95formula847]

thatll have to wait until next rebuild. i already paid for the other piston kit and im on a time constraint to get it done by next weekend.

[95formula847]

i got the engine back together with all new gaskets and piston/rings. cant fire it up yet im waitin on the new procircuit platinum 2 pipe. cant wait to see how it runs with more than 75 psi compressio

[95formula847]

i put the old pipe on to run it. the new pipe is going to take a few days to get here. this is after i broke it in.

http://www.youtube.com/watch?v=foTDiyQOUNs

[Hillclimb#42]

Its possible that it had a carboned piston and then a hard run or a cleaner burning fuel or hotter condition, or as Stewart said, a small coolant leak, washed the carbon off and the loose carbon caused the ring wear. The sleeve will wear faster than the nicasil, too. You might want to get back to a stock cylinder so you can run a tighter piston tolerance.
  Sounds good on the vid you posted. I see you needed boots, now. Did it fix the compression readings?

[95formula847]

I'm fairly sure it wasn't leaking any coolant but you never know. Also, for me to go back to a stock cylinder i would have to buy a new cylinder correct? And i forgot to say in my last post that i was posting the video to make sure the "clacking" noise is normal. I'm probably just paranoid and that's just how they sound. Lol i am pretty positive the compression is good now as its about 10 times harder to kick! Starting in anything but riding boots would be hell!

I took it down the street after breaking it in to see how it ran and its def a big difference. It will pull the tire off the ground in every gear! The jetting could be messed with but i just wont run the bike until i get the platinum 2 pipe on and v3 reeds in. Then ill jet it accordingly.

[95formula847]

well guess what!? it wasnt leaking coolant before but now it is! i didnt wanna say earlier but when i got the cylinder back from the shop i found a crack that was not there when i took it. i was dumb and figured it wouldnt hurt anything so went ahead and put it all back together anyways. i know im dumb. should of taken it to the shop and raised h*ll.

anyways the crack is spread from one of the head studs to the water jacked on both sides of the stud. it goes both ways from the stud. is the fix welding? its only leaking on that stud and it doesnt look to be leaking into the cylinder as i removed the head to see. and yes go ahead and call me dumb i deserve it lol. the piston and cylinder look bran new except for alittle oil on the piston. but it cleaned right off.