Viper compression


I checked two vipers with low miles (1600 +/-) and the PTO was 115, center 125 and Mag 125 PSI. These readings were taking when the engine was warm.

Don't forget not all compression testers read the same. Some get weaker over the years.
 
viperken said:
I checked two vipers with low miles (1600 +/-) and the PTO was 115, center 125 and Mag 125 PSI. These readings were taking when the engine was warm.

Don't forget not all compression testers read the same. Some get weaker over the years.
Click to expand...

Hmmmm.....really,, ok then i've never seen one that low stock.
 
There have been multiple post's on this subject, 110-115, 125-130 is a common reading. I have checked the compression every year on mine since it was new. It's always been in that range using different tester's, or a least untill I pulled two layer's out of the head gasket. Then add 10 psi to those reading's! ;)!
 
I have two testers and both mine read the same. I always check on a cold engine with the throttle pulled open.
 
from the day it was new pto 116,center 126,mag 124
2 years old,2800 miles removed center layer of gasket and gained 11 psi
more than readings above.
 
journeyman, we know you've got a good runnin one!!!

I've probably checked 20-30 Vipers since they've come out in 2002. On average they have ranged from 110 (pto), 125 (center), 125 (mag) on the low side to 125 (pto), 140 (center), 140 (mag).
 
Funny thing is my Dad's is a hair quicker than mine. His compression is 130/145/145......just a hair better than mine. Before I piped it (and burned it down) my numbers were not as good as his. I had around 125/138/139. Then of course ,I got it rebuilt with new pitsons, rings and two new cylinders...OUCH!!$$$....and now it is stronger than it was originally. Go figure.
 
mine 4000kms original no engine mods and 130 pto 142 center 145 mag.

Damn thing should blown about 4 times by now
1. folded over carb boot(damn dealer drove before i noticed 1500km)
2. fliped on side and didn't burp oil line ( olny had 50 km on it)
3. Filled the hood full of snow and was sucking water through the carbs enough ti trip the check engine light on an 02
4. lent it to my bro and he did # 3 again even worse(iced up the carbs with carb heat on

Damn thing still go's, best sled ever built imo.
 
Well if you have those #'s kirkswim , it's very close to mine. I assume it's a runner. Mine runs with or beats 800 twins. I have raced one F7 and beat it handily, and it also runs with all my buddy's RX-1's. I can't complain about that I guess. Now an APEX.....forget it.
 
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