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I have a 97 Indy 500 (nothing but trouble so far) last year I had numerous mechanics look at it. Someones scraps I think.
anhow I came to realize that it has two different pistons in it. How much would this effect the performance in it. it runs not to bad right now but not as good as my 3 friends indy 500's. should I change them out to the same bore and type?
 

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Well, I don't believe you want two different sizes.

The first thing I'd do is to measure the inside diameter (with the correct tool) to make sure they're both the same. If they're not, the smaller one needs to be bored out to the same size as the larger one. However they both want to be of a correct bore (not an obscure one), so that you can install matching piston and rings.

I personally wouldn't run it the way it is, as it can only lead to problems down the trail.



1997 XLT SP 600
"Engage the Mechanism"
 

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Well Spud, T-fin is right. You want to check the bores to see if they are different in size or if they are the same. If the bores are the same and someone just replaced the piston with a different brand, thats still no good. You want two of the same size and brand, pistons and rings. If one weighs more or less than the other, the sled will not run at its best and your just asking for trouble later on. Basically with two different pistons your motor is way out of balance. This isn't NASCAR or NHRA where every motor is balanced and blueprinted, but you want every cylinder as close as possible. Same bore, same clearances with the pistons, same ring end gap etc..... Spend the money now and save yourself some headaches down the trail.

'HAMMER DOWN !!'
 

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it will rob you of everything. as some of the forum members now i had the same problem last year with my 83 indy 600. Big bore kit with 2 correct pistons and one from a 440 i think it was.first time you gave it gas went like a raped ape let off and try going again??? didnt think so. replaced all three pistons with new ones that were the SAME riding wheelies everywhere thru my yard. one thing to check does one piston have the boost port and the other dont??? that was my problem the 2 correct pistons had the boost port and the other one didnt . How many miles are on sled??? it might be a good idea for a rebuild if the sled has higher miles on it. just my thoughts and expierence



Bobby
My wife said its Her or the sleds........ I'm sure gonna miss her

Stop Inbreeding....... Ban country Music
 

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you can have a difference of .020" between your two (or three) piston sizes and not have any problems. Seriously, it doesn't make that big of a difference... Much over that, you may get into balance/vibration issues....

-Dean
 
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