piston broke up

[Seneca Jim]

So I was out riding today and the bike quit running. Got towed home. I knew it was bad as there was no compression when I tried to start it. Got home and took off the head and saw the piston was tore up above the rings right around the exhaust port. Inside dome of head is all grey along w the spark plug. I can't post pics now as I'm posting from my phone. Pics tomorrow. This question is burning me up. I changed the clip setting on the needle in my carb. It was set all the way on the top slot and I moved it to the second from the bottom as that is what Pro Circuit recommends as I run their pipe and silencer. It's killing me thinking that I probably caused this to happen. So did my moving the setting on the needle possibly cause this to happen? Thanks.

[cobbs]

I highly doubt the needle jet position would cause that to happen

[Motorrad]

agree'ed... in the direction you moved it...



Cast piston by chance..   

[GREENKAW24]

If it had been running a while at that needle setting (clip all the way up) prior to moving the clip to the Pro Circuit setting, the piston may have been cooked already from running too lean. It was just a matter of time.

[cobbs]

I highly doubt it had anything to do with the need jet setting it might not have helped to lean the clip but I think the the jetting as a whole is too lean what's your jetting and elevation, and where are the pics it would be easier to tell what type of failure you had if we could see

[Seneca Jim]

Thanks for answering my post everyone. I'm trying to put up a pic as an attachment but I get this message, "The attachments upload directory is not writable. Your attachment or avatar cannot be saved." And I don't have a site to put it up on. Anyways I will post my jetting settings in the next couple of days and try the picture thing again. I was sure that I had put a pic up on here before but I must have forgotten how I did it or something has changed here on the site. I'll be taking the cyclinder off tonight and will take more pics. If anyone has any ideas on how I can post pics I'd appreciate it very much. Thanks. Jim

[alward25]

You have to host the pics through a place like Photobucket. 

Good Luck
Alex

[Polar-Bus]

So I was out riding today and the bike quit running. Got towed home. I knew it was bad as there was no compression when I tried to start it. Got home and took off the head and saw the piston was tore up above the rings right around the exhaust port. Inside dome of head is all grey along w the spark plug. I can't post pics now as I'm posting from my phone. Pics tomorrow. This question is burning me up. I changed the clip setting on the needle in my carb. It was set all the way on the top slot and I moved it to the second from the bottom as that is what Pro Circuit recommends as I run their pipe and silencer. It's killing me thinking that I probably caused this to happen. So did my moving the setting on the needle possibly cause this to happen? Thanks.

Your top end was going to fail regardless of jet needle clip position. Post pics of your piston. Failed pistons always offer visual clues as to why the piston failed. The #1 cause, is lazy air filter cleaning maintenence, and sucking dirt. Be forewarned, if your piston granaded , your crank is probably not too far behind....

[Seneca Jim]

Thanks for the replies everyone. polar-bus, funny you should mention the air filter. That was one of the first things I replaced when I bought this bike. It looked factory and was all torn up. Also you mention the crank, I took the piston off and as I cycle the engine around the rod hangs up when it's on the downstroke. Not sure if it's debris or a bearing issue but regardless it needs rebuilt I suppose. It's a 1993 motor and was probably used and abused the last almost 20 years so I guess it should come as no surprise that it has finally let go. cobbs, the jetting is N82M needle, 168 main, 55 pilot, clip was at top of needle but was moved to 2nd from the bottom, @ 1,381 ft. elevation. Well I started a Photobucket account and posted some pics. http://s1049.photobucket.com/albums/s393/jimmykx500/ I hope this works. I don't think they are very good but it's the best I can get out of my little camera. I'll maybe try using my phone next. There's a big gouge next to the exhaust port. Will that junk the cylinder? I'm not sure what should be done about the cylinder. I've read about the coating on these so I guess that will have to be done at some point? I'm at a loss as to what needs to be done to the cylinder and need some help. A bore and hone with a new piston and rings sent along with the cylinder? I don't have a lot of $$$ as I just bought a house and am now out of work but I am wondering if I should just send this all out and have it done. I'd like to save some $$$ and do it myself but would hate to go through all the work and end up taking it somewhere anyways. I appreciate any and all input. Thanks, Jim

[cobbs]

ouch man that sucks but it looks to me like that bike was running super lean it looks like the ring fused to the piston and your jetting seems to be in the ball park for your elevation but every bike is different either way that looks like it got REALLY hot, and the cylinder damage looks like it was mostly your nikasil (plating)chunking off it definitely looks repairable but depending on how deep it goes you might need to sleeve it instead of recoating it also you cannot just bore and hone a plated cylinder, you will either have to have it replated or sleeve it. Was the coolant full in the bike, or possibly an improper mix of fuel?

[Polar-Bus]

Holy melted piston batman...

Well, thats definately a serious WOT melted piston. How about some more precise details how the engine behaved right before the granade ?

[Seneca Jim]

Polar-bus, it was running ok just before it let go. Pretty much as it always had. I've looked at some things and may have figured out what some of the problems were that caused this to happen. The pipe is so bent up, it wasn't bolted to mount at front of frame, that it was touching the right radiator hose while at the same time the short hose on the left side that goes from the lower part of the radiator to the head was a regular piece of hose that was not formed so it was bent slightly and restricting the flow of coolant I'm sure. Add to that that I may possibly have been adding double the oil to my mixes for the last 2 months. I just moved this year and had all my fuel mixing stuff misplaced. I was mixing in a 2 gallon can last year w a measuring cup and couldn't find neither of them this year and was in such a hurry to ride I started mixing in a 1 gallon can while using a different container to measure the oil and I may have forgotten to cut the oil in 1/2 for the new can. Live and learn. My cylinder is going to Langcourt for welding and plating and a new Wossner piston set, the crank's going to a place in New Hampshire for a crank kit and I'll get new hoses and will work on bending the pipe back myself maybe. I'm going to put up a new post regarding the pipe now.