Here's a doozy

Youllbe2nd

Youllbe2nd

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Joined
Feb 14, 2015
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425
Location
Canada
After a good season I decided I would check my top end and do a re-ring depending on condition. Sled has 5300 miles now. Checked compression and it was 90/118/95... Uh oh. Pulled top end and found mag piston is smoked. Other two are clean. Cyls and head are clean. Get this, mag and PTO cyls are PORTED and middle is not. Looks like the guy before me replaced the middle cylinder at some point on a ported motor and never matched it. Also smoked piston appears to be different brand than the other two.
I know I have found the specs before on this site but can't seen to find it now. What are that wear specs for viper cyls and pistons?
 

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Viper same. Yamaha stock i thought was .0028 - .0036. Wiseco I use .004 -.0045
Ten thousandths would rattle itself to death.
 
Sorry let me clarify my statement, the wear LIMIT is 10 thou (0.010"). Stock clearance is .0028 to .0030 measured of course at the skirt. This is strait out of the manual for a 2003 Viper.
 
Using spx aftermarket pistons here. Don't judge me. The pistons came with instructions saying .016" to .039" for bores 66-70mm sound right? I've heard cheap piston rings expand more than stock. Should I aim for .016?
 
Is there a good way to measure to ports? I have a set of bore gauges and a good vernier. I figure I'll need to do some porting work on the middle cylinder to match it up
 
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