How to do a Compression Test

[2fast4u]

When testing compression : Cold engine: Be sure your battery is good and fully charged to max befor testing, Remove all 3 plug wires and store them safely away from the engine area and be sure there is no gas or fumes in hull, remove only on sprakplug at a time ( leave the other two in when testing ) Un plug electrical power valve servo motor, be sure power valves are closed, hold throttle full open when testing, record gauge reading, repete test again on same cyl. just to get a good reading, then do the same on the other two cyls. If you battery seams to slow down during testing re charge battery between each cyl. test , This is the only way to do a good compression test IMO, Tommy Jordan

[canadaxp]

Un plug electrical power valve servo motor, be sure power valves are closed

Question, what difference would this make in the final comp if one did not do this? I am assuming it would bring it up a bit?

[2fast4u]

Question, what difference would this make in the final comp if one did not do this? I am assuming it would bring it up a bit?

ON my 2000 gpr when you are doing a compression test the power valves will cycle open then close. I un hook the servo to be sure I get a constant reading and record this info and save it for future information so I can check my motor to see if It it still good to go or that the compression has started to go away for some reason, I usualy see 3 -6 psi higher with the power valve servo un hooked and valves down. Keeping a good data log of information on your motor when its fresh ( In good working order) helps you later when you supect something might be going wrong with your motor, Tommy Jordan

[OsideBill]

Great post Tommy, I copied it and made it a "how to"

this test applies to all 2 stroke skis, if you do not have power valves ignore that portion.

[stlouisramsfan]

Great post Tommy, I copied it and made it a "how to"

this test applies to all 2 stroke skis, if you do not have power valves ignore that portion.

When i read this last night, i thought it should be "stuck"
thanks

[Hybrid AWD]

I'm getting ready to go look over a GP1300R this upcoming Wednesday and I was just reading over the manual and seeing what I could find online about things to look for and I cam across a conflict between here and there.

In the manual it says to remove all of the spark plugs instead of just one at a time. What is the reasoning as to why you recommend to leave one out at a time?

Also, why do you recommend disconnecting the PV servo?

Lastly, what is the benefit to doing a cold reading vs. warmed up (118* F) as the manual says?

I'm not questioning your method, just trying to make sure I do it properly and get accurate readings the right way. Thanks.

[steach]

Also, why do you recommend disconnecting the PV servo?

This ensures that they all stay closed while turning the starter (consistancy).

What year 1300R? The 2005+ dont have power valves.
Follow the directions above. The key is having a FULLY charged battery.

[Hybrid AWD]

This ensures that they all stay closed while turning the starter (consistancy).

What year 1300R? The 2005+ dont have power valves.
Follow the directions above. The key is having a FULLY charged battery.

It's a 2003 GP1300R. I'm gonna send the guy an email asking him to make sure the battery is fully charged.

[sandman7793]

Why in the yamaha manual does it say the compression on a 2001 xlt 1200
is 500 kpa on a tester that equals around 72 psi and my cylinders are around 110 psi which i think is kinda low ANY HELP

[steach]

Why in the yamaha manual does it say the compression on a 2001 xlt 1200
is 500 kpa on a tester that equals around 72 psi and my cylinders are around 110 psi which i think is kinda low ANY HELP

The spec in the manual is for a minimum compression. 110 is a tick low but if its consistant you should be alright