Compression test - PSI ? Advice needed

[sickric]

I have been having a pressure build up in my coolant bottle. After the machine is warmed up , I stop somewhere along the trail and shut it off, a little while later it will bleed coolant out the overflow. ( No Visual leaks anywhere else on the motor.)
I did a compression test today , = 120 mag side 120 center 110 pto side.
Do you think the low pto side and the pressure problem are related ?
Is the 10 PSI difference something I should be concerned with ? (rule of thumb is 4% difference right?)
All plugs are beautiful tan color, Sled runs and starts great, has 3400 miles on it.
Any thoughts ?

 

[Mysledblows]

I'm not a viper guy, but didn't they run staggered compression on the PTO side so that the carbs are jetted the same on all three?

 

[sickric]

I am not sure about that, good question, anyone else know about this ?

 

[9801srx]

I'm not a viper guy, but didn't they run staggered compression on the PTO side so that the carbs are jetted the same on all three?

thats right. there usually about 10 lower on the pto.

 

[bluebandit98]

i had a head gasket go on my 98 xtc 700 an it would build pressure in my coolant system an blow the cap off of the colloant overflow botle.

 

[Yamasquaw]

Just did one on my Viper, has just over 12,000km's/7500miles approx. And it was 135,135,110. Which i thought was great considering havent touched it yet.

 

[sickric]

O.K. Thanks for the replies everyone. Maybe the compression is O.K. I will try and fiind out why I am building pressure in the coolant bottle.

 

[02ViperMtn]

i read in a recent thread that i recall the issue was a head gasket leak. A tell tale sign was bubbling in the collant overflow while the machine was running.

 

[SRX700guy]

could be the head gasket? does it run hot and overheat? if so it could be a air pocket in the cooling system somewhere that is causing it

 

[02ViperMtn]

check this thread.

http://www.totallyamaha.net/forums/showthread.php?t=55852