02' Viper Compression?


Doing a leak down test, requires a leak down tester tool. A leak down tester, is a tool that uses compressed shop air.The tool continously pump's a regulated amount of air into the cylinder, while a pressure guage on the tool monitors the pressure bleed-off (leak down) rate pass the rings (and valves on a four stroke).
During the test, the crankshaft must be locked with a bar. This is to prevent the piston from moving down and exposing the exhaust port and venting out the air pressure.
All engine's will have some leakage, because of ring end gaps, and the required piston/cylinder clearences. A leak down of 10% or less is considered an acceptable seal.
 
MrViper has posted that before and it is very good info. Maybe one of us can do a little formatting on it before we move it to the Tech Pages just to make certain portions stand out a little better. If it is ok with you guys, maybe I can see what I can do. Maybe we could add some info to it as well. I could paraphrase and convert the skidoo leak-down test procedure. Also, I think there is some good posts on www.SnoWest.com that I may be able to plagiarize. Great info MrViper.
 
Try a different tester. Alot cheaper than the alternative. I had the same problem and discovered my tester was wrong.
 
sounds good to me , i dont think you can have to high ? could be wrong though ...
 
Well finally got a new tester to use(mac tools) and readings were alot better.Tried to find a leak down tester in thunder bay and no one had one. So i made one for about 30 bucks from Home Depot and have to try it out one night this week.
 
There are several variables for different compression readings. Such as altitude, temp, air density, engine machining tolerance's, overall engine condition, and of course the tester itself.
Compression reading taken at higher elevation, will be lower then at sea level. This is because of the less air density at alttitude.
Yamaha has a production tolerance of .3cc for the cylinder head chamber. While this is not a large amount, it is possible for one engine to have .3 cc's smaller combustion chamber's then another engine. This could make a difference of a few PSI.
The ideal way to monitor your engine's condition, would be to take a compression reading right after the motor's broke in. Say at approx 500 miles. Then once a year after that, (using the same tester).
Below is a pic of a leak down tester (Snap-on). They are a simple and easy tool to use.
In this case my sled tested (3000 miles) out at,
PTO, 122 psi 6% leak down
CTR, 141 psi 8% leak down
MAG, 140 psi 7% leak down
Reading's were taken with 2 head gasket layer's removed. Stock head gasket reading's are 10 psi lower. Compression reading's are the same as when the sled was tested at 500 miles.
 
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Those number though are for a viper piped right??Where can i find the right compression for a stock viper,and the leak down i believe should be at 10% or lest,correct??
 
Stock Viper generally measures at the following:

-PTO CYLINDER: 115
-MIDDLE CYLINDER: 130
-MAG CYLINDER: 130

On the leak down tester, I don't like to see anything over about 8%, but that's just personal opinion.
 
Well after compression checking about 30 of them over the last 4 years that's the average numbers at roughly 2000 ft elevation that I've seen.
 
I was curious,not that I was doubting what you were saying.its a good thing to now a certain base line.115 pto,130,130.Thanks
 
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