fitz18 Posted October 24, 2008 Report Posted October 24, 2008 Ok guys so Ive blown up my engine and am trying to figure out why. Here's my set up: 2001 shee, dmc alien pipes, k&N filter in box snorkle removed, 240mains, stock pilot, air screw 1 1/2 turns out, 40:1 mix mild ported cylinders i bought of firehead on here I started stripping down the bike and noticed the keeper screw and clamp that tightens agianst the left hand carb cap (stock carbs) is missing. would that have an effect on it? O some info: wen i say blown up the pistons are intact but the left crack rod came out through the case. Did alot of damage. Have got new crank, new cylinders, new pistons, and while im at it im sticking in a new trans. Bike ran great before blew up although sometimes it would bog under low revs. Any icdes. Thanks Gerard Quote
Badapwned Posted October 24, 2008 Report Posted October 24, 2008 Sounds like you might have found your issue. If that left side carb was loose and sucking excess air in, you may have created an extremely lean situation and we all know what happens when 2 strokes get to lean for to long > Sorry to hear your bike blew. Quote
fitz18 Posted October 24, 2008 Author Report Posted October 24, 2008 Thanks man. I didnt realise them screws/clamps were so important. I thought they just ensured the carb cap stayed on Il post some pics of the pistons and the damage casued. Anyone else wants to chime in please do. Quote
dekker Posted October 24, 2008 Report Posted October 24, 2008 I would also dare say that 240 main is too lean for that setup My guess is it should be somewhere around 280 ish Quote
fitz18 Posted October 24, 2008 Author Report Posted October 24, 2008 Im in ireland. 262.5ft above sea level. I was at 220 and went to 240. Do you think it is still lean with this info? I asked the local guy for 260 and he said it would just flood her. I thought my jetting was about right. Quote
05.Banshee.SE Posted October 24, 2008 Report Posted October 24, 2008 Best way to find out is to plug chop her. Quote
fitz18 Posted October 24, 2008 Author Report Posted October 24, 2008 If i was running lean on my mains would I not have done damage to the pistons? Like a hole in them or something? I will do a plug chop when I get her up and running. I read a post on here somewhere and some guy was saying the keepers on the side of the carbs are important, so I was just wondering how important they are. When I get home from work il get pics of the pistons and crank uploaded. Quote
magz Posted October 24, 2008 Report Posted October 24, 2008 you sound lean to me, i had a similar set up at one time with no port job and i was running 290's. even your ported you might consider even bumping up to 320's Quote
fitz18 Posted October 24, 2008 Author Report Posted October 24, 2008 you sound lean to me, i had a similar set up at one time with no port job and i was running 290's. even your ported you might consider even bumping up to 320's What was your elevation? We have an average temp of 46 fahrenheit here. Anyone more ideas? Quote
dragbanshee Posted October 24, 2008 Report Posted October 24, 2008 That screw&clamp only holds the cap from vibrating loose, I think you would have noticed the difference in how she was running if that cap backedoff much. It would have been ideing higher and not running near as good as before. Doesn't sound like any kind of lean condition, with what happened, but I would still bump up on your mains. Quote
BenBB Posted October 24, 2008 Report Posted October 24, 2008 I agree that sounds lean but I also agree the damage doesn't really jive with a lean condition failure. Rod through the case, ouch :ermm: I'd like to see some pics... Quote
fitz18 Posted October 24, 2008 Author Report Posted October 24, 2008 I'll get the pics up real soon. Looking forward to hearing some feedback. I am basically putting in a complete bew engine apart form clutch. :biggrin: Keep the points of views and ideas coming though. The help is great!! Quote
desertdeweller Posted October 24, 2008 Report Posted October 24, 2008 are you the original owner if not its possible that the previous one, could have run the bike lean and got the rods hot and one failed. I don`t if a crank slipping could cause a failure like that or not. rods pull tremedous g forces at bdc and tdc it could have just been weak to begin with. Quote
magz Posted October 24, 2008 Report Posted October 24, 2008 (edited) What was your elevation? We have an average temp of 46 fahrenheit here. Anyone more ideas? you have a lower elevation, and a general colder condition of air which means you get alot more air then we do with hotter air which means you should be richer then most everyone here in general. with that info hell id even be running 320s, your pretty damn lean no ifs ans or buts.... also id mix gas at 32:1 which means your be getting more oil, less gas which will help keep the motor cooler then id go to the guy who said anything bigger then a 240 would flood it and id punch him square in his fucking face for wasting your money on a rebuild you wouldnt have had to do. Edited October 24, 2008 by magz Quote
Midway USA Posted October 25, 2008 Report Posted October 25, 2008 (edited) Mine did a similar thing except it didn't kick the rod out of the case. I had run mine out of gas and my co-worker said running out of gas on a 2 stroke can be bad if it happens at a decent speed. I killed a needle bearing on the crankpin. I currently have 270 mains and I have been running 32:1 2R. Edited October 25, 2008 by Midway USA Quote
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