2018+ cylinder compression

[firecat225]

Wondering what you guys have got for readings when doing compression tests?

Im more of a low elevation rider. I bought an 18 and realized it ate snow when i pulled pipe and pistons were scuffed.

Had 140/142 for compression. I put new pistons and rings and piston pin bearings along with having cylinders diamond honed by local race shop.

60 miles on new setup and both show 143. I did warm up twice and shut down to cool. Then ive been doing lots of throttle chops and some 1000ft wide open pulls.

Hoping it goes up more yet once it has a few hundred miles. Just ordered the defender intake kit.

Checked pistons through y pipe yesterday everything looks good and no blowby like old pistons had.

Also run about 12 oz of oil to a tank of gas to help with lube.

 

[Goinboardin]

My good running '18 had 105 psi on both sides somewhere around 1500 miles. This was cold, at 7200' above sea level. If running on the 3% per thousand feet above sea level guide, that would put mine around 135 psi if measured at sea level. This was a cheaper gauge. 145psi sounds very healthy to me, especially if it's running well, skirts look good, and it's even side to side. Write that number down for your baseline and return to it for comparison if the sled starts running poorly or compression becomes a concern in the future.

 

[slyrydr]

that amount of compression sounds very good to me, i've rebuilt a number of 2-cycle engines over the years and i don't like a lot of compression unless i'm primarily drag racing..

 

[nytro41]

Mine was running 115/117. still run really good so i am not sure where i am supposed to be cuz that is a long way off 145 LOL

 

[bnorth]

145 is probably in the ballpark depending on your elevation.

 

[Ntimmermann]

I'm at 785 feet. Cold, around 128psi both sides.
Just checked the intake and some of those gap you could fit a beachball through ffs.
Sealed up nice and tight now with RTV silicon. I guess I better pull the Y-pipe and see the damage.

18' MC 980mi.

Sent from my EML-L09 using Tapatalk

 

[badaltitude]

Cold or hot? I’d run it at 128...just me though. Most likely nothing wrong especially if it was 128 on both cylinders

 

[Ntimmermann]

That's cold, I'm not worried about the numbers but better safe than sorry for the 10 minutes of work.

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[zl5600]

There are way to many variables with the gauges. If you are within 5% between, you should be golden.