steven Posted July 13, 2009 Report Share Posted July 13, 2009 well i got a 421 cheetah cub with 35mm pwk's, p/d cool head with 22cc domes, T5's, stock reeds, +4 timing, and 115 long rod.my jetting is at 170 mains and 58 pilots with air screw 1 an 1/2 turns out. at sea level. i ran my bike in pismo this weekend and blew my right piston. my nickelsill looked good and had NO nail catchers. the only thing wrong was a thin film of aluminum left behind by the piston. at the time i was running the bike on 87 pump fuel. i know it was a DUMB ASS IDEA!!! but i changed both pistons out there. then i used a 50 50 mix of 87 and C12 race fuel. now it backfires in first gear when i punch it.and the rest of the gears have power but its not all there. im still running lean and have tried bumping up on the mains but its not making a difference. i need help. and if you have a similar set up can you tell me what jetting your running and your elevation. and what you think of my gas mixture. all advice will be greatly APPRECIATED! THANKS Quote Link to comment Share on other sites More sharing options...
firebanshee Posted July 13, 2009 Report Share Posted July 13, 2009 well i got a 421 cheetah cub with 35mm pwk's, p/d cool head with 22cc domes, T5's, stock reeds, +4 timing, and 115 long rod.my jetting is at 170 mains and 58 pilots with air screw 1 an 1/2 turns out. at sea level. i ran my bike in pismo this weekend and blew my right piston. my nickelsill looked good and had NO nail catchers. the only thing wrong was a thin film of aluminum left behind by the piston. at the time i was running the bike on 87 pump fuel. i know it was a DUMB ASS IDEA!!! but i changed both pistons out there. then i used a 50 50 mix of 87 and C12 race fuel. now it backfires in first gear when i punch it.and the rest of the gears have power but its not all there. im still running lean and have tried bumping up on the mains but its not making a difference. i need help. and if you have a similar set up can you tell me what jetting your running and your elevation. and what you think of my gas mixture. all advice will be greatly APPRECIATED! THANKS I don't think you blew your bike from being lean, you were probably detonating. With a 68mm bore and 22cc domes you were running way to low on your octane.You should be mixing 93 octane with race fuel.Your jetting on that set up should be around 155 on the main and 55 pilot jet with a cel needle. What do your plugs look like? Quote Link to comment Share on other sites More sharing options...
bada450r Posted July 13, 2009 Report Share Posted July 13, 2009 I don't think you blew your bike from being lean, you were probably detonating. With a 68mm bore and 22cc domes you were running way to low on your octane.You should be mixing 93 octane with race fuel.Your jetting on that set up should be around 155 on the main and 55 pilot jet with a cel needle. What do your plugs look like? yeah i dont think you were lean at all...i think you had an airleek....when i had my cub on gas i was running 155mains 55 pilots with a cel needle and it seem perfect...i also run pismo and glamis...and dont ever run cheap gas on a race motor i dont care what your compression says with a set up like that you should be running atleast 100 octane even with 22cc domes..imo Quote Link to comment Share on other sites More sharing options...
steven Posted July 13, 2009 Author Report Share Posted July 13, 2009 right now my plugs are coming out dry and alittle on the grey side. and thats with my cel needle one down from the middle, mains at 170, and pilots at 58. Quote Link to comment Share on other sites More sharing options...
steven Posted July 13, 2009 Author Report Share Posted July 13, 2009 yeah i dont think you were lean at all...i think you had an airleek....when i had my cub on gas i was running 155mains 55 pilots with a cel needle and it seem perfect...i also run pismo and glamis...and dont ever run cheap gas on a race motor i dont care what your compression says with a set up like that you should be running atleast 100 octane even with 22cc domes..imo thanks bada ill check if i got an airleek. Quote Link to comment Share on other sites More sharing options...
VegasJeff Posted July 13, 2009 Report Share Posted July 13, 2009 thanks bada ill check if i got an airleek. Do you have a dual outlet pingle valve?You could be running the bowls empty and that would be a lean condition as well. Quote Link to comment Share on other sites More sharing options...
sandman81 Posted July 14, 2009 Report Share Posted July 14, 2009 Do you have a dual outlet pingle valve?You could be running the bowls empty and that would be a lean condition as well. x2, Happen to me but the bowls where to small. So I bought some Chariot Performance bowls, problem solved Quote Link to comment Share on other sites More sharing options...
No Limit Powersports Posted July 16, 2009 Report Share Posted July 16, 2009 Have you run a compression check on the motor. And a leak down. If your plugs are grey your lean, either from not enough jetting or an air leak. On all new motors always always do a leak down or your asking for trouble. Check the compression and get it to pass a leakdown and let us know. Quote Link to comment Share on other sites More sharing options...
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