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low compression


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ok,,,im a newbie here so please bare with me. i just got my banshee out of layaway,it suppossedly has a 410stroker moter in it,,,i bought it at a used cycle shop and thats all the guy knows. i had a stock banshee a couple years ago that was just piped and k&n filter,,its definately alot faster than that. sadly enough it has a stock head on it and junk tires. i ran a compression check on it today and only came up with about 130 on both sides,,,i hear no piston slap whatsoever,,,,,seems really low,,,about where should i be and what possibilities of it being so low? any replies appreciated

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What's your elevation? 130 isn't low. As long as they're both close to the same compression, you're fine. If it gets down around 110, I'd start worrying. Unless you're at high elevation. Plus, it depends if the stock head was milled out for the stroker. How much was it milled? Or, does it have a spacer plate under the cylinders?

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with an uncut stock head and stock port height's 130 is about right.pull the head and look.head gaskets are cheap

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What's your elevation? 130 isn't low. As long as they're both close to the same compression, you're fine. If it gets down around 110, I'd start worrying. Unless you're at high elevation. Plus, it depends if the stock head was milled out for the stroker. How much was it milled? Or, does it have a spacer plate under the cylinders?

nope no spacer,,im at sea level. when i got it the other day i ran it down the road a couple times,,,after i shut it dow nsmoke just kept coming out of both sides of exhaust,,,i drained the gas and ran half race fuel and half 93 at about 40:1 to clean all the bad gas and or rich mixture previous idiot had in it. no longer smokes at all,,,just at start up as any 2 stroke should when cold. i rode today for about an hour and it runs alot stronger than a piped banshee,,,has keihin carbs,,,not sure what size and have to do a tear down to find out whats been done to it.gonna put a cool head on it,,,what size domes should i run?

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nope no spacer,,im at sea level. when i got it the other day i ran it down the road a couple times,,,after i shut it dow nsmoke just kept coming out of both sides of exhaust,,,i drained the gas and ran half race fuel and half 93 at about 40:1 to clean all the bad gas and or rich mixture previous idiot had in it. no longer smokes at all,,,just at start up as any 2 stroke should when cold. i rode today for about an hour and it runs alot stronger than a piped banshee,,,has keihin carbs,,,not sure what size and have to do a tear down to find out whats been done to it.gonna put a cool head on it,,,what size domes should i run?

At 130 static compression you shouldn't need race fuel or a mix. The domes you run will dictate the fuel you should use. I would choose my domes based on the performance I am after. Smaller domes = higher compression = higher octane.

 

SP

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At 130 static compression you shouldn't need race fuel or a mix. The domes you run will dictate the fuel you should use. I would choose my domes based on the performance I am after. Smaller domes = higher compression = higher octane.

 

SP

so if my compression is at 130 right now and i throw a coolhead on it and run say,,,,20cc domes in it can i get away with 93 octane and what would 20 cc domes boost my compresion to? the only reason i ran half race fuel was to clean the system out a little bit,,i used to run 93 octane mixed at 32:1 with belray oil on my old piped banshee,can i run it a bit leaner?,,,im running 40:1 until this tank is gone then back to 93 octane. how much of a performance gain will the coolhead with 20cc domes give me? it will be ported for sure this winter after i see whats been done to this poorly maintained banshee,,,idiot had a stock foam filter that was just a clump of hard ass dirt,,,changed the oil and it was blacker than coal,,,,stretched out chain had to be replaced(done today) and the whole chain slider set had to be replaced,,,among other things it does run suprisingly strong

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Before you buy domes you need to figure out if its stroked or not. Remember if you need stroker domes the sizing changes. From what I gather 24cc stroker domes are the limit for pump gas

ya,,i'll probably just run the stock head on it till i do a tear down on it this winter,,im not gonna trust this guy telling me its a 410 stroker motor till i find out for myself. i cant even tell how fast it really is with these junk tires(spider claws) i get nothing but tire spine even on asphalt. it will wheelie up to third gear tires spinning the whole time,,,,lol...anyone ever use stock 400ex rear tires on a banshee? they hook up great....

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