800R Compression

[JohnnyH]

I have a 09 154 with 570 mi that I have been fighting belt problems all year.

I have a 14:1 RKT head and have not had any Deto problems.
I just checked my compression cold and the PTO side is anywhere from 130-140 and the Mag side is 160 consistent at 4500' and 55*

What is the compression spec for a stock motor?

Anyone know of any compression/top end issues ???

 

[BlackSummit]

I know this they should be the same or within a few lb's of each other.

 

[winter brew]

I would be mostly concerned about the difference in comp.
As for belts, if you are running anything close to stock, that is the cause of many belt and performance issues.

 

[triple7]

Ya man, dont worry bout the belt problem right now. I would pull the head and have a look at the topend. The last time mine did that it had broke the end of the ring off.

 

[JohnnyH]

Yea, I was just thinking that it might me the answer to the hunting RPM and low pin weight I have been trying to work out.

Back to the dealer after a few more rides.

Just putting it out there to see what other 800R top end problems people have had or if it is even a common thing.

 

[evandaigneault]

stock engine compression on the 800R should be right around 120 on each side at about 5000'.

 

[onlyrotax]

I've always been told you need to check compression with the motor at operating temp. I checked my (stock) 800 HO last night as I was putting it away, 142# on both sides at about 4200 ft elevation with 1240 miles, maybe the 800R has a different spec.

 

[evandaigneault]

The 800R is supposed to have lower compression than the 800HO. Thats what the dealership told me anyways.

Evan

 

[Polecat]

Pull the head and observe the missing end of the ring. Sorry.

 

[triple7]

Ya what polcat said. I wouldnt ride it before you look. It eats the cylinder, ruins the head and gets a bit ugly. And yes, it will cause your pin weight and rpm issue. I had a bunch of work into working out a new clutch kit when I didnt realize mine was doing it. Fix it and you will go right back to where you should be with the clutching. Or call winter brew. He can fix it.

 

[JohnnyH]

Ya what polcat said. I wouldnt ride it before you look. It eats the cylinder, ruins the head and gets a bit ugly. And yes, it will cause your pin weight and rpm issue. I had a bunch of work into working out a new clutch kit when I didnt realize mine was doing it. Fix it and you will go right back to where you should be with the clutching. Or call winter brew. He can fix it.

That has been my whole season. lol