03bansheeLE Posted August 31, 2009 Report Share Posted August 31, 2009 Hey I just did a complete rebuild on my Banshee because it melted a piston in the right cylinder, now it melted a left one yesterday. Ive had the thing running for about a week and a half and got about 2 tanks of gas through it. It was running amazing and I did a plug chop to check main jetting and it looked good, about a 2mm thick ring near the base of the porcelin. I warmed it up for about 5 minutes until my trail tech said about 120 degrees Fahrenheit and took off down the road with my buddies and got right up into 6th gear. As soon as I got on the throttle hard it bogged down and stalled. Wondering if anyone has any ideas? Im just about baffled and close to giving up, Two rebuilds since christmas... My mods are: Wiseco 4mm Stroker, 5mm Long rod crank F.A.S.T. 4mm Dune/Play ported stock jugs 0.040 over Wiseco 795 pistons Chariot head with 21cc stroker cut domes 35mm Keihen PWK carbs with 165 mains, 48 pilots, CEL needle third(middle) clip Billet intake with integrated crossover V-force 3 reeds Shearer Pipes K&N pod filters It had 150psi in each cylinder and I did a leakdown test after I assembled it and it only dropped 1 psi in 10 mins. I also have some pictures to show once I figure out how to post them. Ill be happy to provide any more info, If anyone has any ideas they would be greatly appreciated. Thanks Darren Quote Link to comment Share on other sites More sharing options...
03bansheeLE Posted August 31, 2009 Author Report Share Posted August 31, 2009 Pictures: Left cylinder exhaust side Right cylinder exhaust side Left cylinder intake side Right cylinder intake side Left piston intake side Right piston intake side Left piston exhaust side Right piston exhaust side Left piston top Right piston top Quote Link to comment Share on other sites More sharing options...
x_doug_x Posted August 31, 2009 Report Share Posted August 31, 2009 (edited) i vote airleak or that pistons carbs main jet was clogged some or something.... that looks nasty....... i don't understand how it continued to run like that.. unless you were riding it around on one cylinder. now that i think about it, is there any chance you plugged the plug wire into the opposite side this time and it blew out that piston? if so, maybe your stator or coil is bad? Edited August 31, 2009 by x_doug_x Quote Link to comment Share on other sites More sharing options...
ToomeySheeLE Posted September 1, 2009 Report Share Posted September 1, 2009 (edited) Whoa.. Sickening! Is it a Boss intake your using? Alot of people have found them to have airleaks.. I took the rubber pieces off and put some sealant on them, then tightened them back on.. Never had a problem.. Your doesn't sound like it could be off nearly enough to cause that.. And not to be a smartass, but your certain that the piston rings were seated correctly in the ring groove? I see in those pics that they aren't, but its easy to have em slide out of place while holding them.. Edited September 1, 2009 by ToomeySheeLE Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted September 1, 2009 Report Share Posted September 1, 2009 its not your coil or stator and it doesn't matter which plug gets what wire....the coil fires each plug @ the same time. i never played w/those kehin carbs that you are using, so i can't help on the jetting.....you know, tell you wether or not you are too lean. double check for air leaks around the boss intake, like others have stated. i've read on here, that they have air leaks? maybe crank seal? Quote Link to comment Share on other sites More sharing options...
sheerider1026 Posted September 1, 2009 Report Share Posted September 1, 2009 Whoa.. Sickening! Is it a Boss intake your using? Alot of people have found them to have airleaks.. I took the rubber pieces off and put some sealant on them, then tightened them back on.. Never had a problem.. Your doesn't sound like it could be off nearly enough to cause that.. And not to be a smartass, but your certain that the piston rings were seated correctly in the ring groove? I see in those pics that they aren't, but its easy to have em slide out of place while holding them.. i will agree.. from the pcs, it looks like you forgot to lign your ring gaps up with the locater pins on the piston, causing the rings to wear excessively from the locater pins holding them out against the cylinder too tight.. Quote Link to comment Share on other sites More sharing options...
Rodneya Posted September 1, 2009 Report Share Posted September 1, 2009 Check the gas cap breather and the fuel valve filter. You could be running lean due to the carbs running dry at WOT. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted September 1, 2009 Report Share Posted September 1, 2009 Where the ports Chamfered when you put it back to gether? Quote Link to comment Share on other sites More sharing options...
03bansheeLE Posted September 1, 2009 Author Report Share Posted September 1, 2009 Thanks for the replies. I've heard about the problem with the intakes but I did a pressure test with the intake on the engine and it held up quite well. I thought about the stator/coil problem because its roasted two right pistons (stock one and vito's super stock) and now a left piston with this new complete rebuild. Looks like a vacuum leak to me too but it held pressure fine. All new seals and gaskets in the whole engine. I am 100% that the rings were seated correctly, I even double checked after I started to slide the jugs on by looking through the intake ports. Carbs are brand new never used, made sure they were nice and clean when I put the jets in. I never thought to check the tank breather, I just cleaned it all out, ill check that right now. Thanks again guys. Quote Link to comment Share on other sites More sharing options...
03bansheeLE Posted September 1, 2009 Author Report Share Posted September 1, 2009 Where the ports Chamfered when you put it back to gether? Yes I checked that before assembly, thanks. Quote Link to comment Share on other sites More sharing options...
03bansheeLE Posted September 1, 2009 Author Report Share Posted September 1, 2009 Check the gas cap breather and the fuel valve filter. You could be running lean due to the carbs running dry at WOT. I just checked the breather, looks good. I opened the petcock and the fuel poured out, when I covered the breather tube the fuel slowed down and then almost stopped, I uncovered the tube and it started pouring out again. Quote Link to comment Share on other sites More sharing options...
03bansheeLE Posted September 1, 2009 Author Report Share Posted September 1, 2009 Im using Yamaha 2-R oil since this rebuild and mixing at 40:1. Correct me if I'm wrong but I thought that was a safe ratio to mix at. Also, what kind of plugs do you guys use? Im using NGK BR9ES plugs. Could a leaking exhaust O-ring at the jug cause air to be sucked in when the exhaust pulse creates a vacuum in that area and then the pulse from the forcing cone coming back towards the port push the air into the engine? Quote Link to comment Share on other sites More sharing options...
ToomeySheeLE Posted September 1, 2009 Report Share Posted September 1, 2009 Did you break the motor in on 40:1 as well? Quote Link to comment Share on other sites More sharing options...
sheefreak Posted September 1, 2009 Report Share Posted September 1, 2009 What are you doing for assembly lube? Quote Link to comment Share on other sites More sharing options...
bansheesa Posted September 1, 2009 Report Share Posted September 1, 2009 Are you sure your clearances where fine after re-bore? Quote Link to comment Share on other sites More sharing options...
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