2012 SBA compression at 90psi

[inkstreme_05]

Hey guys,
Running a 2012 SBA 800 with 1167miles, completely stock other than can and clutching. I did a compression test on it today and only came out with 90PSI on both sides. What are the odds of that? The sled seems to run perfectly fine and have lots of snap. the sled was cold(stored in a garage not heated and +4 outside) when I did it but I don't think that matters does it? what is my next step? Fix Kit?
Any Help Or Advice Appreciated,
Thanks!

 

[tinkerjohnson]

Hey guys,
Running a 2012 SBA 800 with 1167miles, completely stock other than can and clutching. I did a compression test on it today and only came out with 90PSI on both sides. What are the odds of that? The sled seems to run perfectly fine and have lots of snap. the sled was cold(stored in a garage not heated and +4 outside) when I did it but I don't think that matters does it? what is my next step? Fix Kit?
Any Help Or Advice Appreciated,
Thanks!

Some gauges can be wrong but I would run it warm the engine and check it agin hold the throttle wide open and pull it over till the needle don't move anymore and see what it says, if your sure your gage is accurate and that's all you have I would change your pistons, it should be around 120

 

[inkstreme_05]

Some gauges can be wrong but I would run it warm the engine and check it agin hold the throttle wide open and pull it over till the needle don't move anymore and see what it says, if your sure your gage is accurate and that's all you have I would change your pistons, it should be around 120

Is holding the throttle wide open how it should be done? cause I didn't do that.

 

[tinkerjohnson]

Is holding the throttle wide open how it should be done? cause I didn't do that.

It will fill the cylinder with air better and faster but should make the same end results

 

[rotax]

Also, elevation is very relevent to these types of posts.

Being in SK I'd guess you wouldn't be above 3k feet? So it sounds like your def. on the low side.

Here are some numbers from mine, same gauge/tester, same engine.

2/20/2012: engine rebuilt @ ~1400 miles/90 hours.
compression:
11/30/2012: cold = 120 Mag/120 PTO @ ~120 feet, ~605.5 mi/37.3 hrs since rebuild.
12/28/2013: cold = 70 Mag/70 PTO @ ~7200 feet, ~1346.4 mi/87.4 hrs since rebuild.

Correcting for elevation, with 3.5% loss per 1000 feet, results in a compression of : 87.15 at sea level, my compression was way low. Not sure if that correction measure is proper, but I read it somewhere on some forum on the internet....so its more than I had to go off of before finding that number.

Anyway, just throwing that 3.5% per 1000' number out there, even if you were at say 3000 feet. OK compression should still be ~107 PSI.

I'd do pistons/rings ASAP before something breaks....because they do....

 

[inkstreme_05]

Rotax - do you have a suggested "fix kit" that one should use?

 

[waxer]

Holding the throttle open is the proper way to check compression. As someone said it might be worth checking with a diff gauge. My 600 runs a constant 125 to 130 and my 14 800 seems to be about 125 at 3500'.

 

[inkstreme_05]

I know the gauge works cause I tried it on a buddies sled afterwards just to make sure and it read properly on his. well I assume it did it read 105psi on his I think its an 2002 F7 with 3500miles.

 

[Carlos Randolph]

Engine warmed up, key off, throttle wide open, pull 4-5 times or til the tester quits going up, read pressure. 120-130 on a good tester, have to have a good accurate tester. Checking your buddies sled does nothing, using a different tester back to back does.

 

[waxer]

^^^^^^^^^^ Actually having a fairly low test on your buddy's would make me believe maybe your gauge is bad! I would at least want to check it with a different one,