1991 ski doo 583cc engine compression - Snowmobile Forum: Your #1 Snowmobile Forum

supercrew · 10-24-2009, 09:12 PM

Hey, Im looking at buying a 1991 583cc motor for my 1990 formula mx lt. The one guy ive been talking to has one but its out of the machine and has been sitting for a few years. I want to do a compression test to it when i go to see it but not sure what good compression is on that moter. does anyone know roughly?? or exactally?? lol

He has done som mods to it, this is what he sent me about the moter;

I have a 583 out of a 91 formula plus, the engine is tunnel ported and has the cylinders ported by fast and has the brass wear plate installed. It was taken out of the sled a few years ago and has been sitting. I have the stock twin pipes that fit that sled. It has 44mil carbs that go with it. let me know if your interested
I'm looking for about $500 bucks.. has two sets of pipes, open race pipes and twin mach1-x pipes for a prs chassis. The engine has been sitting for a few years, but ran good when it was stored, was going to make a asphalt sled.

Do you think this is a good deal? how strong would this motor be to use as a daily trail rider? Is there any way i can make sure that the moter is actually a 583, like a tag or stamp?? if so where would it be located??

Hope to hear from somone soon that can answer most, if not all, of my questions. Thanx so much

JR Hollywood

SkiDoo86 · 10-24-2009, 11:36 PM

As for compression, it should be ATLEAST 120 psi in both cylinders, and both cylinders should be within 10% of each other. Make sure you hold throttle WIDE OPEN, when doing the compression test.
As for the motor. I am unsure if its a good deal or not. If it was made for asphalt racing, youll have to RE-jett it for cold weather. Because it was changed over to run in warmer weather.
Ive always been a little "iffy" on motors rebuilt by someone I dont know. But use your own judgement.
The stock 583, was one heck of a BULLET PROOF motor. Stock, non modified.
TO identify it, there should be some sort of numbering in the side of the juggs, labeling it as a 583 cc or something close to that.
Hope this helps.

supercrew · 10-25-2009, 12:18 AM

ok, the motor is out of the machine and on a shelf, how do i hold the throttle wide open to do the compression test?

stangcruzin · 10-25-2009, 08:43 AM

Sounds to me like all the right things were done to the engine.You'll have to ask the guy if it ran on pump gas or something else.
This does sound like an awsome deal with all the pipes and 44 mil carbs.
Don't worry about holding the throttle wide open to check compression,the results will be the same.

SkiDoo86 · 10-25-2009, 01:22 PM

I dsagree, If you dont hold the throttle open your not getting the full amount of air jammed in the cylinders. The readings will be a little low. Hopefully, RJ will chime in on this.

**RJ Gleason** · 10-25-2009, 06:37 PM

You can just pop the carbs out of the flanges if you need to, then you can still get a good reading.

supercrew · 10-26-2009, 08:43 PM

so if the compression is 120psi in both cylenders you think i should jump on this deal??

**RJ Gleason** · 10-27-2009, 09:39 AM

As long as both are within 10% of the other and the engine feels smooth when it is rolled over.