I was hill shooting, hit 4th up a hill, and the left cylinder went out. Wouldnt fire again. It has spark, and gas. I held my thumb over the plug hole and kicked it over, and it blew my thumb off the hole, so there is compression. But it didnt blow my thumb off every time the piston reached the top, it kinda took 3 -5 strokes to blow it off. But, I took the head off, no scorched cylinder wall, no burnt hole in piston. The piston does have some slop inside the sleeve. How much should it slop around? Both sides have it, with the left having a teeeeny bit more than the right, but the right still fires. My father says that the slop should be there because the piston does float on the rings, but I dont think it should have as much as it has. The engine didnt seize, so I dont think I melted the rings. Could someone please help me with this???


-nick

 

just to help you out by renewing the post and try giving you an answer. What is some slop? When I put the piston back into the cylender after a new rebuild there was ABSOLUTELY no slop at all. How are your reeds. Check everything that has to make a good seal in order for the cylender to actually fire and turn over. Such as in a 4 stroke the valves have to be closed for the engine to fire and turn over.

 

There should only be .003" clearance between the skirt of the piston and the cylinder wall. A little more clearance at the top of the piston, but not much more.

Do you have spark on the dead cylinder when kicking it over?

You only require four things to light it off. Spark, fuel, oxygen, and compression.

I can guarantee you have oxygen. Its the other three you need to check on.

Do a compression check on both cylinders and see if they are relatively close. You did say the one side is still firing right?

I am also assuming you didn't simply foul a plug.

 

oh he defintaly has gas. and spark. we know he has gas cause he took off the pipe, and poored about 20 oz. of gas out of one of them. and spark cause he put a brand new B8EV in and it was sparkin. but no firein.

 

Sorry for not replying sooner. The dead cylinder did have spark, and I didnt have a compression tester at the time, but the compression blew my thumb off the plug hole the same exact way the the right cylinder did. The piston had slop at the top, but not much. You could feel it move back and forth, but it was a very small amount. Im throwing the head back on this weekend, and using the auto parts store lend a tool system to get a good quality snap on compression tester so I get an accurate reading. If thats not the problem, who knows what it could be. Only thing I have in mind is the kinda cheap seals I put on the reed spacers leaking or a broken reed all together...


-nick

 

a few more things the engine needs to run, exhaust has to be able to escape, the reeds have to be kinda working, and the fuel mixture has to be halfway decent (IE: no stuck float making the mixture uber rich or nothing)

This is a good chance for you to get in shape though [img]i/expressions/face-icon-small-smile.gif[/img] my RD wont run under about 3k and the whole thing is just plain running like crap so it takes me about 20 kicks to get it started, and they have to be fast lol.

 

Given all the other posted suggestions been looked at. Do you still have the TORs box still connected? Any oil leaks around the flywheel area, possible bad crank seal? I would try unplugging the TORs unit, then run a pressure test, assuming its got compression, fuel and new spark plug. Robert.

 

Nope, dont even have stock carbs on it. I have Keihin 29.5 (bored) PWks. I Just recently put on 1/2 inch reed spacers, and tightening and getting these long screws to fit in there right was a challange, so my best guess, other than rings, is a loose carb boot.

-nick

Oh, and thanks for all of your guys help with this!!

 

87Banshee250sx>>>> dude, hang in there.....I hope you start firing on both cylinders soon!..its probally just a small fix...

liquidsand

 

Yeh, it was a pretty stupid thing that happened. Part of my airfilter in my air box got sucked into the left carb. God was I happy. I rode it around for a little bit, then I was turning around, and I got it up on two wheels, and it just died. I had a Warrior pull me to get it started because I couldnt kick start it. It got going, but guess what cylinder it was firing on.. ONLY THE LEFT!! The one that didnt work before! I dont know what the problem is now. It wasnt the air filter either.. Im hoping its the gas line or just bad gas or something. I dont have any idea, until the next time I get to work on it, I will have an idea..