Snowmobile Fanatics banner

21 - 33 of 33 Posts

·
Registered
Joined
·
2,626 Posts
you cant compare to drastically different motors in terms of compression numbers. They are a totally different design, and therefore, brand new, ideal compression numbers will be different. a 2001 600 that was brand new may have around 140 lbs of compression while the new 09 will have 130. Not every engine has the exact same compression numbers from the factory. They all very greatly depending on design.
 

·
Registered
Joined
·
208 Posts
Discussion Starter #22
Thanks boys, the open throttle was the main reason why the numbers were off.

I have 120 in both cylinders. What a relief!

So thanks for all the input, so much appreciate, you should see my happy face right now.

Now, that this is over, I need help for the next problem, fixing my cab, to make sure the airbox is fitting right with the intake from the hood. here's a pic, you see that it is a bit off.

But before you answer, please do it in my other post. It's call, "Option for an airbox"

Thanks gentlement
2009128202313815_26840.jpg
 

Attachments

·
Registered
Joined
·
392 Posts
Low revs compression pressure of a healthy engine will be more dependant on port timing than anything else really.
 

·
Registered
Joined
·
208 Posts
Discussion Starter #24
baldur said:
Low revs compression pressure of a healthy engine will be more dependant on port timing than anything else really.
I'm not sure I understand your point, is having a low revs compression pressure is good or bad?

Thanks
 

·
Registered
Joined
·
330 Posts
PolarisIQ600HO said:
baldur said:
Low revs compression pressure of a healthy engine will be more dependant on port timing than anything else really.
I'm not sure I understand your point, is having a low revs compression pressure is good or bad?

Thanks
I wouldn't worry about the compression I have 110 and 115 as well, and the dealership mech. says that is normal.
 

·
Registered
Joined
·
392 Posts
PolarisIQ600HO said:
baldur said:
Low revs compression pressure of a healthy engine will be more dependant on port timing than anything else really.
I'm not sure I understand your point, is having a low revs compression pressure is good or bad?

Thanks
As 03prox700 said, you can't compare the measured pressure between different engines. And even then, when doing a compression test you're more interested in the differences between cylinders than anything else, the numbers on their own don't tell anything conclusive unless they're really unusual.
 

·
Registered
Joined
·
208 Posts
Discussion Starter #27
Mr.Dummie said:
PolarisIQ600HO said:
baldur said:
Low revs compression pressure of a healthy engine will be more dependant on port timing than anything else really.
I'm not sure I understand your point, is having a low revs compression pressure is good or bad?

Thanks
I wouldn't worry about the compression I have 110 and 115 as well, and the dealership mech. says that is normal.
I'm at 120 since I did the test with the open throttle! So I'm all good
 

·
Registered
Joined
·
317 Posts
i did another compression test today. i don't think i was pulling the cord hard enough. my dragon has 112 in the right side and 115 in left side. that's not very bad is it? my freshly rebuilt xc 800 has 125 in each side though.
 

·
Super Moderator
Joined
·
11,272 Posts
FastPolaris said:
i did another compression test today. i don't think i was pulling the cord hard enough. my dragon has 112 in the right side and 115 in left side. that's not very bad is it? my freshly rebuilt xc 800 has 125 in each side though.
Thats not bad,but for a new sled I dont see why they shouldnt be the same still. I would just keep checking it every few hundred miles to see if it changes any more. Maybe even take your throttlebodies off and look in the cyl at the pistons to see if there is any kind of minor scoring or scratches.
 

·
Registered
Joined
·
317 Posts
RMK-KING said:
FastPolaris said:
i did another compression test today. i don't think i was pulling the cord hard enough. my dragon has 112 in the right side and 115 in left side. that's not very bad is it? my freshly rebuilt xc 800 has 125 in each side though.
Thats not bad,but for a new sled I dont see why they shouldnt be the same still. I would just keep checking it every few hundred miles to see if it changes any more. Maybe even take your throttlebodies off and look in the cyl at the pistons to see if there is any kind of minor scoring or scratches.
i'm going to bring it up and take all the exhaust off, y-pipe included. see if i see anything really noticeable. if i do see some bad scoring do you think that polaris would cover it?
 

·
Registered
Joined
·
1 Posts
I just compression tested (used a Sun compression checker) my 2001 Polaris RMK 800 - following the advice on this page....throttle wide open, 5 good pulls. Both cylinders read 135 PSI. This sled has about 3500 miles on it, but I am guessing it can wait another year, I don't really push this sled hard, use it for ice fishing.
Looking for confirmation that 135 PSI on both cylinders is good to go.
 

·
Registered
Joined
·
1 Posts
I just compression tested (used a Sun compression checker) my 2001 Polaris RMK 800 - following the advice on this page....throttle wide open, 5 good pulls. Both cylinders read 135 PSI. This sled has about 3500 miles on it, but I am guessing it can wait another year, I don't really push this sled hard, use it for ice fishing.
Looking for confirmation that 135 PSI on both cylinders is good to go.
Yes. 135 is good compression. Below 120 in just about any engine and there is a problem.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
2,581 Posts
I wouldn't say below 120 is a problem so much. Consistency between all cylinders (10%) is what you should be most concerned about unless your number is staggeringly low.

That said, it sounds like your engine is in good mechanical shape.

Sent from my moto z3 using Tapatalk
 
21 - 33 of 33 Posts
Top