I did a compression test on my 03 wolverine and it came up 90-95 psi..So I was like time for a ring job because the manual says it should be around 110-120 psi..I called my local dealer and talked to one of their tech guys and asked me if I had the throttle wide open when I did the test?I did not,he says thats why you are at 90-95psi.Test again wile holding your throttle wide open,that is the way Yamaha determines their specs..So I did what he said and it was right around 120psi..Can anyone here confirm this way of testing,wile the Yamaha tech says its the way to do it,the manual says nothing about the throttle that I have seen??

 

well did you have the atv warmed up?
To get a proper reading on the compression it needs to be warmed up so that you can have the rings expanded so they are meeting the cylinder walls properly. But I do hold the throttle wide open as that is the way most manufacturers do check compression.

 

yeah she was pretty warm..I did that test after a bunch of carb adjustments tests..Thanks for the confirm on the throttle..

 

ya i always do it throttle open. Alot of times i tried it both ways and honestly never seen a difference in psi, but sometimes it does. all the manufacturers specs say throttle open, so best to do it that way...

 

Yep, the throttle must be held wide open, or you wont get the proper reading. All the text books and service manuals say it as well.

 

<div class="FTQUOTE"><begin quote>Originally posted by: HiLi_Psyclez

ya i always do it throttle open. Alot of times i tried it both ways and honestly never seen a difference in psi, but sometimes it does. all the manufacturers specs say throttle open, so best to do it that way...</end quote></div>

I too have noticed that it doesn't always make a significant difference in the readings.