How big of a problem is this??

M

mikerx

New member
Joined
Jul 8, 2008
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46
Age
53
Location
Kitchener, Ontario
I just bought an 03 Viper. I went out and bought a compression tester and got readings of 130-135 psi on the 2 cylinders and barely 120 psi on the clutch side cylinder. I warmed it up a little with no improvement. The sled shows 2700 kms on it. Is this major?? Will I be ok for this season or do I need some work done?? Any help would be great!!
Thanks,
Mike :dunno:
 
you have nothing to worry about. that pto (clutch side) has a larger cc dome volume for the head, so it will read less psi than the other 2 cylinders.
 
Vipers came with a lower compression piston / head assembly on the #1 cylinder. This was to allow for straight - across jetting on the triple carbs. (If you noticed, all main and pilot jets are the same for all three carbs). It's normal for the #1 cylinder to have lower compression. According to yamaha documents, the compression ratio on the #1 cylinder is 5.9:1, while #2 & 3 are 6.7:1. Hope this helps...
 
Wow!! Thats almost 15 psi!! I know with my old RX-1 it had to be pretty close on all 4 or you were looking at trouble so I figured it was the same with the Viper.
 
You guys just saved me from a heart attack!!!!!! The sled didn't even come with an owners manual or a repair manual so I have only the experts on this side to refer to!! Thanks Guys!!!!
 
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