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Discussion Starter · #1 ·
Hi: I have a 92 Indy 650. Last year I went threw 2 pistons however in diffrent postions. I,m currently using .020 wisco lites but I,m beging to think there junk. It's not a lean problem as I always check the plugs. They burn down right in the middle. I'm going to install stock .020 this year and install duel fuel pumps as I'm thinking it's a fuel starvation problem.
 

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One thing to keep in mind is that the 650 doesn't take to well to excessive piston to wall clearences espcially with wiseco's. Not sure on the exact specs but i have heard that this engine needs more attention in this area than most other engines. I've heard many people with alot of experience with this motor recommend the kimpex pistons as well. On snowest forums do a search on indy 650 and there's lots of posts pertaining to building a 650.
 

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If your burning down on the PTO bad, better check that cheap little seal on the PTO. It can be changed without tearing down the engine.
 

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well if the plugs look good i'd say its not a fuel problem at all. I guess i'd check to be sure you are running the correct heat range spark plugs.
 

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The correct plug is the champion rn2c.
 

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I never had good luck w/ the champs.. I ran NGK BR9ES

try puttin' a one size bigger main jet on the PTO..

and I agree w/ indytriple.. I had bad luck w/ the wiseco's.. 2nd take of gas the piston skirt broke.. could have just been a fluke.. but that was enough for me..
 

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Check your ignition timing. 650's were very picky about having the ignition timing near perfect. 1 or 2 degrees retarded, and they fouled plugs by the handful, and 1- 1 1/2 degrees advanced they would eat pistons like candy.
 

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I've been hearing that kimpex is the way to go , because they have some give and, are more precise ?


Wiseco have to be perfect and the clearence must never change.
The reason why your loosing wiseco piston's could be that
if you look at one , there are ridges around the piston, you can feel them on the side of the piston, when they are boared to the size of the piston, the piston is measured according to the outside of the piston Which means there is a 10 thou edge there that will weare down and cause too much clearence and the skirt starts to slap then boom !

Kimpex are smooth on the side so what you measure is more acurate.

Rule of thumb with kimpex is to break in the piston's
tear it apard and look for scoring on skirt and sand the high spots down a bit.. this is because they are not round and that's how you find out the high spots.

wiseco are perfectly round.


Also it could be the plug caps,,,,,
Not sure about that but i'm waiting for feedback on it.

plug caps with resistance multiplyed by 3 could retart your ignition timing.
 

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Discussion Starter · #9 ·
Hay thanks for the tips. I called wisco corp and they said it most likly is a timming problem so ocne I,mn back together I'll check it out. Again Thanks to all for the help.
 
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