spike4444 Posted October 10, 2004 Report Posted October 10, 2004 I've been running my modded Banshee for a year now and have had no problems. Yesterday I went to a 1/2 mile oval and after less than 10 laps the top end tightened up and scuffed both pistons and cylinders. I was only just getting into sixth gear on the straights so it wasn't being over revved. It seems to have leaned out The quad has never run lean before any idea what might have caused this? Anyone else had similar problems running at 1/2 mile flat tracks? Any help would be much appreciated Cya Quote
Schizo Posted October 10, 2004 Report Posted October 10, 2004 Well if it wasn't lean before but is now then it must be an airleak somewhere. Torn manifold boot? Might have to do a leakdown test... Quote
racer Posted October 10, 2004 Report Posted October 10, 2004 (edited) here is what a leaned out piston looks like. to me yours look like massive blow-by, but it could just be funny lighting. put a new topend in it, bore hone pistons rings gasket, the whole shebang, then do a leak down if you still think it leaned out. Edited October 10, 2004 by therail Quote
Fireman-hott Posted October 10, 2004 Report Posted October 10, 2004 Exactly therail, the onlything is look at his picture again, it was lean only it hadn't melted totally through. Quote
racer Posted October 11, 2004 Report Posted October 11, 2004 (edited) yes, that or maybe a little detonation. spike do you know where your compression was at when it blew? Edited October 11, 2004 by therail Quote
spike4444 Posted October 11, 2004 Author Report Posted October 11, 2004 Hey "therail" the compression is over 170, I was running with octane boost and I believe detonation as well as maybe being a little lean caused my problem. Will detonation cause a melt down like I encountered though? Cya Quote
racer Posted October 11, 2004 Report Posted October 11, 2004 octane booster is shit. you need a 50/50 mix race/pump gases. im not for sure but it looks like you needed a topend for sure, and some higher octane fuel. so once you rebuild it with all of the necessary parts do a leakdown test to check for air leaks. do a search in the forums for a break down on how to build one. Quote
lincster Posted October 11, 2004 Report Posted October 11, 2004 With that compression, you should have been running 50/50 race gas at a minimum. Octane boost doesn't do much. What is your jetting and air filter system? Quote
Capone Posted October 11, 2004 Report Posted October 11, 2004 (edited) I rebuilt my shee broke it in, rode it all the time. One day I took it on a flat track, leaned out and blew up. I dunno, only thing I can think of is the fuel in the float bowl bouncing around. Boysen makes a nice round float bowl for shees w/ stock carbs. rockymountainatv.com has them. Edited October 11, 2004 by VitoBanshee Quote
racer Posted October 11, 2004 Report Posted October 11, 2004 I rebuilt my shee broke it in, rode it all the time. One day I took it on a flat track, leaned out and blew up. I dunno, only thing I can think of is the fuel in the float bowl bouncing around. Boysen makes a nice round float bowl for shees w/ stock carbs. rockymountainatv.com has them. ummm, i think that would one hell of a long shot. maybe you just needed tighter carb clamps. Quote
spike4444 Posted October 11, 2004 Author Report Posted October 11, 2004 I now believe that my problem came from having over 170 psi of compression. I got this info off of "Vito's Performance" and this is what he had to say. "You can assume that your power output will increase 2 horsepower for every 10 psi you raise your cranking pressure. unless you drag race only for 300 ft or less we do not recommend you go past 170 psi it will build heat that cant be dissipated with the stock cooling system without a cool down rest. We get reports that people run smaller sizes than what is recommended above for the specific octane used and you may very well do it for awhile but from our experiences detonation will eventually rear its ugly head and bite the buddy you loaned your bike to." Quote
Capone Posted October 11, 2004 Report Posted October 11, 2004 Don't you have an aftermarket head? Like coolhead, or noss machine, something of the sort? If not, how are you getting 170psi? And if so, you wouldn't have a "stock cooling system". "we do not recommend you go past 170 psi it will build heat that cant be dissipated with the stock cooling system without a cool down rest." Just a thought. Quote
racer Posted October 12, 2004 Report Posted October 12, 2004 spike when you rebuild be sure to run a good race fuel, doesnt have to be anything oxygenated or super high octane. just like VP red or something, and mix it 50/50 with regular pump gas. and what type of head are you running? also even if you had static compression of 170 if you are ported that will also alter the number somewhat, so tell us if your ported or not also. Quote
spike4444 Posted October 12, 2004 Author Report Posted October 12, 2004 (edited) Don't you have an aftermarket head? Like coolhead, or noss machine, something of the sort? If not, how are you getting 170psi? And if so, you wouldn't have a "stock cooling system". "we do not recommend you go past 170 psi it will build heat that cant be dissipated with the stock cooling system without a cool down rest." Just a thought. Hey VitoBanshee, The stock heads were shaved down 30 thou. I was told this was okay to do but obviously it wasn't ! My re-build will definetly include a cool head of some kind. Anyone ever try a Vito's Hemi head or are there better ones on the market? thanks. Cya Edited October 12, 2004 by spike4444 Quote
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