What is considered normal compression?

[winter4ever]

I went to check the compression on my sleds today just for the heck of it. Both sleds were running great on the last ride.

On my 09 800 rmk I was only getting about 65 psi in each cylinder, and each would hold the pressure.

Checked the wifes 06 600 and it was getting about 55 psi in each cylinder and each would hold the pressure.

Elevation here is about 2000 feet.

Since both sleds run great I am wondering if my gauge could possibly be wrong, as I thought sleds are generally around the 110psi range. I am glad however that both sleds had the same pressure in each cylinder.

 

[redsnake3]

different gauges will read different numbers, the main thing is the difference in the cylinders. a longer hose on a compression gauge will make a lower reading because it now has to fill all the volume of the hose on the way to the gauge. your numbers seem very low but im guessing that the gauge you have reads low because of the volume on the way to the gauge. try the gauge on a similar sled and compare the numbers

 

[winter4ever]

That's a good idea, ill have to check somebody else's sled. The hose is probably 2 feet long. And after I thought about it, it wouldn't be the cylinder holding the pressure but the gauge its self, so that part doesn't really matter either.

 

[mtncat1]

I doubt either engine would run with that low of compression.

 

[halvy25]

Make sure you're pulling at least three times also. I was told to do that when I borrowed a tester, which also had about two foot of hose. The first pull on my wife's 600 RMK was around 75, but sustained at 118 on the third and consecutive pulls.

 

[sledhed]

Throttle wide open? Multiple vigorous pulls? Key off of course.

 

[winter4ever]

Lots of hard pulls, didn't think to have throttle wide open though. Still think my gauge is just junk. I just bought it too.

 

[mike_s]

Try again with the throttle open, if there is no change return the gauge.

 

[THRILL_SEEKER]

Just a question, what does it do differently with the throttle wide open? I have checked my 09 800 multiple times with multiple gauges both wide open throttle and no throttle and have seen no difference on any reading other then maybe couple psi from one gauge to another.

 

[mike_s]

Just a question, what does it do differently with the throttle wide open? I have checked my 09 800 multiple times with multiple gauges both wide open throttle and no throttle and have seen no difference on any reading other then maybe couple psi from one gauge to another.

If you happen to have an engine that pulls high vacuum at idle, then the throttle opening at idle could potentially be small enough to affect a static compression reading.