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Compression Testing


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#1 Mr. Lee

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Posted 12 November 2016 - 12:38 AM

When I do a compression test 60 in one and maybe 50 in another. I was told compression on this sled was 130. Am I maybe doing the test wrong? 

 

I removed spark plug. 

Attached the hose to the gauge where the spark plug was. 

Pull rip cord 3 times. 

 

I also have the airbox out, but I did not think that would make a difference. 



#2 woltersmachz

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Posted 12 November 2016 - 01:02 AM

Remove both spark plugs, hold throttle wide open during cranking. If #'s are under 120 you need at least a new top end.Give each cylinder @5-7 good pulls.If cylinder pressure is more then 10 psi different you need to rebuild. There are many other steps afterwards but let's get that first step done.

#3 kenwilkin

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Posted 12 November 2016 - 03:17 PM

if its a 800R with the factory air operated raves the covers must be off and someone pushing valves in



#4 Mr. Lee

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Posted 12 November 2016 - 04:37 PM

Sorry for my ignorance. This is my first snowmobile. But what covers are you referring too that need to be open during the compression testing?



#5 Mr. Lee

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Posted 12 November 2016 - 11:11 PM

Remove both spark plugs, hold throttle wide open during cranking. If #'s are under 120 you need at least a new top end.Give each cylinder @5-7 good pulls.If cylinder pressure is more then 10 psi different you need to rebuild. There are many other steps afterwards but let's get that first step done.

 

I did it your way and got 55 psi on both cylinders. 



#6 smurfy71

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Posted 12 November 2016 - 11:53 PM

If the sled runs you have more then 55, Try a different gauge.

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Shop Manual (ask me for a link)

 

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#7 kenwilkin

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Posted 13 November 2016 - 10:10 AM

What sled do you have. Year model engine?

#8 Mr. Lee

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Posted 13 November 2016 - 11:11 AM

What sled do you have. Year model engine?

 

2007 Ski Doo Summit Adrenaline 800r



#9 Mr. Lee

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Posted 13 November 2016 - 11:15 AM

If the sled runs you have more then 55, Try a different gauge.

 

The gauge is brand new. I purchased it just for this project. Thats why I started thinking I was doing it wrong. 



#10 skidooracin77

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Posted 13 November 2016 - 11:27 AM

I would prefer a known good guage vs. Brand new one. Borrow a known good guage

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#11 smurfy71

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Posted 13 November 2016 - 11:44 AM

The gauge is brand new. I purchased it just for this project. Thats why I started thinking I was doing it wrong.


Does the sled run? If so, I would suggest your gauge is crap.

2004 GSX 600HO SDI

Nun replacement (service bulletin

Shop Manual (ask me for a link)

 

94 MX 470

 

 

 

 


#12 Mr. Lee

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Posted 13 November 2016 - 04:54 PM

Could it be a fuel problem I have?  After I try to start it, the spark plugs are dry and I cant spell gas.  I am getting fuel from the hose that leads to the carb but I am not sure what a good flow should be. On some motorcycles I have had, you can drain the carb bowls and check if fuel is getting there. Is there a way to do that on the Ski-Doo engine?



#13 smurfy71

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Posted 13 November 2016 - 05:33 PM

I think you need to start at the beginning and tell us what got you here. Have you had the sled running at all? Why are you checking the compression? Is there spark?

2004 GSX 600HO SDI

Nun replacement (service bulletin

Shop Manual (ask me for a link)

 

94 MX 470

 

 

 

 


#14 Mr. Lee

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Posted 13 November 2016 - 09:30 PM

I think you need to start at the beginning and tell us what got you here. Have you had the sled running at all? Why are you checking the compression? Is there spark?

 

I bought this sled used at what I felt was a good deal. I knew it needed some work and I thought it would be fun learning how to fix it. On my own, I was only able to get the sled started once. I had to hold down the throttle and when I released it the motor died. The seller said the compression was 130 in both cylinders and it probably needed a good carb cleaning. Sounded doable at my skill level. I replaced the main and pilot jets and cleaned out the carbs. When I put her back together she wont start. I also purchased a compression tested and when I test it there is 55 psi in each cylinder. And I could be doing it wrong. I tested it on my van too and it was also low. Got it on Ebay. Might be crap. idk. I can try to borrow one from a neighbor when I see him.

It could also be possible I put things together wrong.

 

I am no sure what the compression is until I get another tester.

I do get a spark from the spark plug cables.

I cannot not see or smell gas on the spark plugs or the whole the spark plug screws into.

Gas is flowing into the carb. I am not sure how to test if there is gas in the bowls.  I did not see drain plugs like on motorcycle carbs.



#15 woltersmachz

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Posted 13 November 2016 - 09:46 PM

if its a 800R with the factory air operated raves the covers must be off and someone pushing valves in


I'm not familiar with this practice.If the raves are opening while cranking there would be an underlying issue I'm assuming.




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