I bought a banshee three years ago that has served me flawlessly until last weekend when I burned a piston. I torn it down tonight and now have a few I questions-any help regarding any or all questions would be greatly appreciated.

I got no history on the motor when I bought it other than it has been ported. I'm trying to order new pistons but after tearing her down, I can't really read the markings on the pistons-however, what I can see is that they appear to be different from each other.

Does anybody know what the stock bore size (inches or mm) so I can determine what size over these are using calipers?

Also what is the recommended torque req. for the base and head nuts? Also, is retorquing neccessary after break in?

Does anyone feel strongly about one type of piston over another and why?

While I got it apart should I add V-force reeds-do they really make that much difference for the price?

Finally, since this is my first tear down of a shee, is there anything different or tricks I should know before I put it back together? I have rebuilt several 250R's, blasters, etc. I assume it is all the same X's two. Please tell me if I'm wrong.

Thanks,


'Bob

1. don't order any pistons until you have honed the cylinder-because if you didn't catch a "nick" or something it may need to be bored..in which case the piston size can't be determined until after the bore is determined..1over, 2 over, etc.

the pistons should be the same size both sides

there is a difference in front to back of the piston-which you already know I assume (just a reminder)

reed changes only make a minimal gain-is it worth the money? Not for me..these days I would recommened an air filter an outerwear and pipes /rejet..those are noticable gains....everything else is a pricey slight gain...my opinion of course

while you have it apart I would check the carb float bowl needles..that little rubber tip gets grooved and causes the carbs to overfill-now may be time to replace those???? Burning a piston because it was revving too high too long? Or was it running lean? Figure out why before commencing the rebuild.......

My pops burnt a piston on his banshee (ported cool head the whole gig) because he thought I'd be OK to run on 91. Yeah not so good, run at least mix 110/91 and keeps um running good.

that would depend upon compression....I used to run regular unleaded in mine..it never burned nothing in the engine up.......maybe like a trinity stage 5 would require av gas......the whole "high octane" fuel thing is so overstated.....octane is required to prevent pre-ignition of the fuel becaue of tremedous heat being generated by high compression...like if your banshee was running 13+ psi compression..in which case a bottom end to hold that type of explosion would be required or you would shove those rods right thru the bottom.....

Is all I know is before port work, ran on 91, ran hot but on 91. After port work (sundahl big ports -welding on the outside and 2 extra intake ports) would not run on 91 with melting spark plug electrodes. More octane took that problem right away, so you tell me. And yes, it was jetted correctly 330 mains on the stock carbs. Probably could have stepped up to bigger carbs for that much air flow, but my gas mileage was already $h!tty, and didn't want to amke it worse. Besides, gave the appearance of being stock . I agree with your mentality, more octane is not worth it if you don't need it, but if your burning holes in pistons, there is a problem somewhere. Either not enough octane or just not enough fuel. It's lean, so dig in figure it out. My experience, 50/50 race gas and 91 made the bike run cooler (right off the pipe I could tell the difference) and no more detination that burns holes. So give it a try, and if it doesn't make a difference on your ported shee, go back to 91.

Well my 250r ran 16:1 compression running 50/50 race/pump gas but now I put the stock trx headgasket and i am running 92 w/ 108 octane booster and its perfect.. I am running a 170 main instead of like a 165 before, I am going to keep it a little rich so it last longer for me.

Burnt one side look for air leak in that carb, intake boot or loose spark plug or your jetting was to lean but if other side was not getting ready look at that side real close. V-force reeds are not on my recomend list did not like the results lost to much bottom end for me but if you want to run the hill might not be a bad thing for you.