Hack Job Posted December 1, 2003 Report Share Posted December 1, 2003 I was riding out in the desert this weekend and my 01' Banshee decided it didn't want to be there. We had just gotten to camp, unloaded the gear and warmed up the bikes. We probably rode about 10 minutes, basically just cruising (3rd gear not revving very hard) when the bike stalled. I tried to start it again but the bike would cough and die. My brother towed me back to camp and while I was starting it, noticed that the left cylinder wasn't hitting. It would blow cool air, and occaisionally belt out a nasy back-firing sound while the right cyinder was idling. I pulled the plug and it had an ominous grey tone with some flecking. Looked like detonation, so I didn't bother trying to start the bike the rest of the weekend. When I got home, I cleaned the bike, pulled the head and left jug. The left piston had some material missing above the top ring and the face of the piston had the texture of a frying pan with non stick coating. The cylinder wall has material deposited onto it, but may not be grooved. I've attached pics below to see if anyone has any ideas on the cause of death. The gas was a little on the old side, but lit off fine and since the bike wasn't under a lot of high RPM load, I wouldn't figure it to be the problem. Besides, why would the left side be more affected by the bad gas if that was the problem? The bike is relatively stock with stock timing, TORS removed, Toomey T-5s, White Brothers Boost Bottle, no airbox lid, K&N with outerwears, 310 mainjets, 91 octane mixed 36:1 with Maxima 927. I need advice on the repair as well as the possible cause of the problem as to avoid it in the future. Do I need to replace both pistons or only the left side. I would assume I should do both to keep the wear even on everything. Any input would be greatly appreciated as I want to get my bike running again quickly. Quote Link to comment Share on other sites More sharing options...
wheeleymaster99 Posted December 1, 2003 Report Share Posted December 1, 2003 how do the rings look and how was it running before it died and you for sure would replace both pistons at same time Quote Link to comment Share on other sites More sharing options...
Hack Job Posted December 1, 2003 Author Report Share Posted December 1, 2003 well , it was running fine , untill it died , i tryed to kick it but it was siezed. after tearing in to it i found the above. i would also like to know what is the stanadrd bore size. it think it is 64mm but mine messures out at 63.93mm on my mic. i took a small hone to the cylinder but it didnt seem to do any thing. . any help here would be great! Quote Link to comment Share on other sites More sharing options...
Indubitably Posted December 1, 2003 Report Share Posted December 1, 2003 I agree get a fresh bore and hone then throw in some new pistons. Check out your head too make sure there's no pitting. As to the cause it could have been running lean dependeing on your altitude I know when I was running stock carbs I was at a 350 main with an almost identical setup. Detonation could have caused it but how old was the gas? Make sure the jets weren't clogged either. Quote Link to comment Share on other sites More sharing options...
Hack Job Posted December 1, 2003 Author Report Share Posted December 1, 2003 I agree get a fresh bore and hone then throw in some new pistons. Check out your head too make sure there's no pitting. As to the cause it could have been running lean dependeing on your altitude I know when I was running stock carbs I was at a 350 main with an almost identical setup. Detonation could have caused it but how old was the gas? Make sure the jets weren't clogged either. i was at ocatillo wells when this heppened. so you would probably know. that altitude was about 1000 ft. the gas was about 11 months old. and i changed the plugs right before i took it out. oh well ill take it out to the next bore and get some new pistons. after looking in the carbs this eve they looked clean. the mains were not pluged up in any way. well ill clean them all up and put it all back together. Quote Link to comment Share on other sites More sharing options...
Indubitably Posted December 1, 2003 Report Share Posted December 1, 2003 Make sure to use new gas when you get it back together and to get new spark plugs, make sure they are gapped corectly too. I believe Ocotillo Wells is at sea level as is every place i know of to ride in that desert basin. I would check your airfilter too it looks like it really leaned out maybe you have a hole in it or something. Quote Link to comment Share on other sites More sharing options...
tithead Posted December 8, 2003 Report Share Posted December 8, 2003 i dont think its the fuel.... you said that it was blowing cold air. its like there isnt enough compresion for it to fire??????? Quote Link to comment Share on other sites More sharing options...
SandBastard Posted December 8, 2003 Report Share Posted December 8, 2003 Maybe Im wrong, but perhaps its your crank seal? Quote Link to comment Share on other sites More sharing options...
fixitrod Posted December 8, 2003 Report Share Posted December 8, 2003 Looks like the exhaust side of the rings are gone. Can you get a better pic of the cylinder and a close up of that piston. I'd like to see the other piston too. Was there oil in that fuel?? Quote Link to comment Share on other sites More sharing options...
bs125r Posted December 8, 2003 Report Share Posted December 8, 2003 My 97 Shee did the same thing to me about aweek ago. I went to the Badlands in Indiana rode for mabye an hour or so and the left cyclinder died. When I took it apart the upper ring towards the exhaust side was broke and the piece must have been sitting on top of the piston, because the piston and head is trashed. If anyone knows what could have caused this please let me know I don't want this to happen again. The plugs looked ok, the carbs and airfilter were clean, and I just put fresh gas in it. The right side piston and rings are still in good shape. I take some pics of mine later. Here is a link to pics of my piston and head BMX WRIGHT Quote Link to comment Share on other sites More sharing options...
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