M8 Compression Values

Marmot MB

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I have searched here and yet to find a straight forward answer on Compression PSI New and Compression PSI that is concerning.

I am sure someone here knows the answer :)

What is a NEW M8 Compression value in PSI ? my sled is a 2008 EFI

what is a bottom value that would be concerning ?

I have seen a few times that a 10% difference between cylinders is acceptable ?

I have 3586 KM and 148 Hrs on this sled.

I tested as below and had:

Left cylinder 117 cold / 113 hot (of note these are the exact same values I had last year when I tested)

Right cylinder 121 cold / 119 hot

Testing Procedure:

One plug out, compression tester in plug hole, throttle held fully open, start run switch to off, key off.

5 - 7 pulls of cord when cold

5- 7 pulls of cord when hot.
 

mountianguy

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I have searched here and yet to find a straight forward answer on Compression PSI New and Compression PSI that is concerning.

I am sure someone here knows the answer :)

What is a NEW M8 Compression value in PSI ? my sled is a 2008 EFI

what is a bottom value that would be concerning ?

I have seen a few times that a 10% difference between cylinders is acceptable ?

I have 3586 KM and 148 Hrs on this sled.

I tested as below and had:

Left cylinder 117 cold / 113 hot (of note these are the exact same values I had last year when I tested)

Right cylinder 121 cold / 119 hot

Testing Procedure:

One plug out, compression tester in plug hole, throttle held fully open, start run switch to off, key off.

5 - 7 pulls of cord when cold

5- 7 pulls of cord when hot.


The numbers you have are good, anything under 100 is probably a concern. The difference between the cylinders is more important and 10 % is acceptable. Number vary from year to year and with gauges too. The 800 HO may have more compression than the 07-09 800. A turbo engine will have a lower compression. I have seen different gauges give alot different numbers on the same engine. If you are testing for the piece of mind the engine is healthy mission accomplished. If you are troubleshooting a problem keep looking. The Suzuki 800 is as close to bullet proof as they come. I did read a nice upgrade is to install the HO pistons in the older engines. I have no first hand experience but it most likely gives you more compression, and may require 91 octane. I have seen many of those engines with double or triple the mileage your has and never been apart. As far as new goes your's would be in the 120 -125 range. Your elevation plays a role in compression also, sea level will have the most and it drops as you go up. I hope this answers your questions.
 
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