CAJUN BANSHEE Posted April 24, 2011 Report Share Posted April 24, 2011 Had a reputable builder in my area build me a 4mil which includes: +4 crank, trued and welded, new weisco pistons, full drag port, 34pj's, cool head with 20cc domes @ 140lbs compression, running 112 vp, wicked intake, timming plate at +4, lock out with r6 clutches. Ran 1 1/2 tanks in bike around the house and shee pulled hard but cut out bad on top end and was fouling plugs (motor was broke in by builder). Brought bike back and my builder took the 160 mains out the carbs and replaced them with 140 mains. Bike ran great and spark plugs had a cardboard color, everything seemed fine. Went to the dunes last sat. and made two drags that morning and motor locked up. The right piston skirt on the intake side broke and wedged between the crank and case. Thank God the bike was just at an idle when it happened. Just wanted some feedback if anyone might know what may have happened or if it has happened to them. Sucks, a few thousand dollars for 2 drags and now another 400.00 to rebuild. Not adding up to me Quote Link to comment Share on other sites More sharing options...
ban565 Posted April 24, 2011 Report Share Posted April 24, 2011 (edited) It has been my experience when running race fuel the plug should be powder white color. I would call your builder to check for sure. Sorry about the motor. Edited April 24, 2011 by ban565 Quote Link to comment Share on other sites More sharing options...
CAJUN BANSHEE Posted April 24, 2011 Author Report Share Posted April 24, 2011 It has been my experience when running race fuel the plug should be powder white color. I would call your builder to check for sure. Sorry about the motor. This is what my builder said it should be, I know on a stock motor on pump gas should be that color for proper jetting but this is my first performance build to anything like this. Quote Link to comment Share on other sites More sharing options...
camatv Posted April 25, 2011 Report Share Posted April 25, 2011 (edited) deto? bad piston? if the skirt broke the porting may be to big on the exhaust OR the piston wall clearance is to much and they rocked in there. if the other side survived measure the wal clearance and figure it out. Edited April 25, 2011 by camatv Quote Link to comment Share on other sites More sharing options...
CAJUN BANSHEE Posted April 25, 2011 Author Report Share Posted April 25, 2011 deto? bad piston? if the skirt broke the porting may be to big on the exhaust OR the piston wall clearance is to much and they rocked in there. if the other side survived measure the wal clearance and figure it out. Well thats the bad thing, its still at my builder and he's out of town. I might be a little sceptable if he bored the cyl. or not. may just have put new pistons and rings and rolled with it. 140 compression sounded low to me for race gas. He claimed 180 when it was built but I checked and it was not. I should pick it up and work on it myself, I am fairly mechanically inclined on 2 stroke motors. Quote Link to comment Share on other sites More sharing options...
camatv Posted April 25, 2011 Report Share Posted April 25, 2011 YIKES Quote Link to comment Share on other sites More sharing options...
ban565 Posted April 25, 2011 Report Share Posted April 25, 2011 Sounds like you will be money ahead to work on it yourself or find a different builder. Quote Link to comment Share on other sites More sharing options...
700vflash Posted April 25, 2011 Report Share Posted April 25, 2011 Build it yourself, they are easy to work on! You will have more pride in your ride knowing you are the one that built it. Quote Link to comment Share on other sites More sharing options...
NOS_350x Posted April 25, 2011 Report Share Posted April 25, 2011 I would find a new builder!!! all bikes are different but 140 seems WAY too lean IMO Quote Link to comment Share on other sites More sharing options...
CAJUN BANSHEE Posted April 25, 2011 Author Report Share Posted April 25, 2011 Thats what im going to do, I rebuilt it about 7 years ago with no problems but it was just stock with all the bolt ons. Looks like I may be using bhq a lot more, yall have been helpful, I guess I was just looking for some support to work on it myself and yall are right I would take more pride in it. THANKS Quote Link to comment Share on other sites More sharing options...
SonOfSand Posted April 25, 2011 Report Share Posted April 25, 2011 what elevation are you? 140 seems lean unless you are 5000' or above. to jump from 160 to 140 is not the best jetting practice. Quote Link to comment Share on other sites More sharing options...
CAJUN BANSHEE Posted April 25, 2011 Author Report Share Posted April 25, 2011 what elevation are you? 140 seems lean unless you are 5000' or above. to jump from 160 to 140 is not the best jetting practice. At sea level or a little below, Im in Louisiana. Jetting may be part of the problem but I think my builder never bored the cylinders therefore the piston kept rocking back and forth until it found something to hang up on, but thats just a thought, I wont really know nothing until I get my bike back from him in a couple of weeks. Quote Link to comment Share on other sites More sharing options...
trx4502shee Posted April 25, 2011 Report Share Posted April 25, 2011 (edited) If he was a good builder and really broke it in he should have noticed if it was to rich or to lean in my opinion it was caused by either to much pistion wall clearence or the squish was not right and the piston hit the head and rocked breaking the piston skirt.This is what happened to my 4mill cause the squish was too tight....banshee piston Edited April 25, 2011 by trx4502shee Quote Link to comment Share on other sites More sharing options...
volcrano Posted April 26, 2011 Report Share Posted April 26, 2011 was the top end noisy at all?u would think if the clearance was that far out,ud hear some clanking,at least till hot.did u have any idle/driveability problems to sway to a lean situation?did he hog out the ports on the piston to match his "drag port"? Quote Link to comment Share on other sites More sharing options...
sleeper06 Posted April 26, 2011 Report Share Posted April 26, 2011 Before you turn a screw pressure test it ,rule out air leak.Then you need to mic up pistons and check cyl on bore guage.But def dont just tare into it look around first Quote Link to comment Share on other sites More sharing options...
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