Banshee problems

[Ripassbrother]

Last summer my banshee quit on me. Only one cylinder was working. I took the top end off and noticed my left piston was toast. Parts of the piston were cracked off and missing. My right piston looked ok.

 

When the bike quit on me it was blowing smoke out. I thought is overheated because I was low on coolant. I tore down the bottom end and inspected the crank. There seemed to be a little play but nothing that concerned me. Could this be a simple overheating problem? or is it more that the piston was knocking the head because of the crank? I bored out my cylinders and just bought 2 new pistons, should I not put the new top end on or do you think I will be ok. I just don't want to put it on again if Im going to go blow it again. 1st post on this site, sorrry Im new.

[SICK BOY]

If the crank is in spec and the bearings are good use it.If it overheated why did it over heat?? If one cylinder was fine and the other was blown,it leads me to believe you had a lean condition it that cylinder.It could of been caused by a loose plug,loose carb boots,wrong jetting or many other things.

Edited May 3, 2005 by SICK BOY

[ssanddemon]

There seemed to be a little play but nothing that concerned me.

364000[/snapback]

A little play is too much. You should feel no play, just smooth rolling when you turn the crank by hand. Play in the crank can make the left (stator) side seal leak air which can taost a piston real easy. You're gonna need to do the bottom end.

[Ripassbrother]

If the crank is in spec and the bearings are good use it.If it overheated why did it over heat?? If one cylinder was fine and the other was blown,it leads me to believe you had a lean condition it that cylinder.It could of been caused by a loose plug,loose carb boots,wrong jetting or many other things.

364006[/snapback]

so what are the signs of a overheated bike? Why do you think only one piston was destroyed?

[Ripassbrother]

so should I be fine guys if I just get a good crank? My bike was blowing steam, do you think that is what happened I blew the seal? So this is all caused by a bad crank jumping around?

[sheefreak]

When you say play do you mean you can move the connecting rod side to side a little, or do you mean you can pull up on the connecting rod and get play. You can have side to side play, once you get the piston in the cylinder , it is not going to move that way. And did your piston look ashy like it burnt up, or did a piece just break off?

[SICK BOY]

so what are the signs of a overheated bike? Why do you think only one piston was destroyed?

364201[/snapback]

 

I would say you had a lean conditon in the one cylinder.

 

When you say play do you mean you can move the connecting rod side to side a little, or do you mean you can pull up on the connecting rod and get play.  You can have side to side play, once you get the piston in the cylinder , it is not going to move that way.  And did your piston look ashy like it burnt up, or did a piece just break off?

364351[/snapback]

 

If there is a LITTLE play in the rods side to side it's ok,but if there is play in the rods up and down then it's time to replace.If your talking about play in the crank itself then junk it.

[Ripassbrother]

you guys are giving great advice. The rods move side to side just slightly. As for up and down on the rod no it dosnt have play. The crank has been trued and welded. what do you think?

[Ripassbrother]

I would say you had a lean conditon in the one cylinder.

If there is a LITTLE play in the rods side to side it's ok,but if there is play in the rods up and down then it's time to replace.If your talking about play in the crank itself then junk it.

364430[/snapback]

My left piston was the bad one, it had a big chunk on the upper side break off. Someone said that the way the head was machined that the piston was hitting.

[sheefreak]

Did you have your head shaved? Was it by someone reputable?

[Ripassbrother]

I was told that the way they machined it increased the compression but also allowed the piston to hit the head.

[bigboybanshee]

This is a dumb question but if your piston had a big chunk taken out of it, did you go through your bottom end and make sure there is no pieces of the piston floating around in your cases? If there are and you don't clean them out, you'd be replacing your crank soon afterwards once those pieces of debri got to the bearings. Just something to think about

[Ripassbrother]

This is a dumb question but if your piston had a big chunk taken out of it, did you go through your bottom end and make sure there is no pieces of the piston floating around in your cases? If there are and you don't clean them out, you'd be replacing your crank soon afterwards once those pieces of debri got to the bearings. Just something to think about 

364485[/snapback]

Yea we allready spit the case and took everything out and cleaned it up.

[Ripassbrother]

anyone else have any feedback to what a I should or shouldnt do?

[sheefreak]

Can you post picks of the piston, maybe the spark plug that was in the bad side? How long did this top end last before the problem occured. If the piston was hitting the head, it would not have lasted for long. If your piston was indeed hitting the head you should see some sort of damage to the head also. We still haven't determined whether or not you were lean. That big chunk that came off could be because it was so lean it burnt the piston right down to the ring landing and finally broke a chunk off. Need more info!