Compression Testing Question

kevinm7

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Spring Creek, NV

• Jan 14, 2013

• #1

2007 Summit X with 1,4xx miles. I am curious as to what a good compression reading is. I live at 5,800 ft and ride from 7,000 up to 10,000. Also, what is the proper procedure for doing a compression test? Do I pull the cord once and that is my reading before I bleed pressure, or do I need to do multiple pulls until the needle stops moving? Total newbie to checking my compression.

Sled starts on first pull when cold, but needs WOT and 4 or 5 pulls to start after it's warmed up. Also, has a low end bog when I first start it after warmed up. Kinda like it's flooded, but once it cleans out the sled runs fine. Any help is appreciated. Thanks guys.

 

winter brew

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• Jan 14, 2013

• #2

Check the reeds and reed boots. Known for delaminating and chipping and that will cause the bog and hard starting.
Comp check....plugs out and yank until gauge stops going up. Not sure what it will be at that altitude, probably 120ish???

 

kevinm7

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• Jan 14, 2013

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Awesome. Thanks for the info. I will be sure to check all of that. Suggestions for reed replacement if they are bad?? Vforce 3? Boyesen? OEM?

 

kevinm7

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• Jan 15, 2013

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Re-tested when I got home and the readings average 127 PTO and 125 MAG. With that I think I am good. Now to pull off the reeds and boots. I am going to order a new set today. Looking for suggestions on what to get. Anyone with experience using Vforce or Boyesen please chime in. Thanks

 

S

sledsrock

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• Jan 15, 2013

• #5

I have the 07, I'm at 4850ft. elevation and when my sled was stock with 1200ish miles, my comp was 125/125....so I'd agree and say you're good. As for the reeds, the 07's did not have the boot delam like the earlier years did. In fact I'd be surprised if your reeds have a problem. If by chance you do need new petals, I would go with the Boyesen carbon fiber medium tension. I would not go with the Rage Cages unless you like giving up power. Stock reeds on that sled are the best.

 

kevinm7

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Sounds like a good plan. I will pull the reeds tonight and check them out before ordering new. Thanks for the info.

 

B

BackCountryBob

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• Jan 15, 2013

• #7

Cold engine. Pull plugs, hold throttle wfo, pull 3 x and check.
125 is good.

Had Boysens and switched to the oem softer--much better mid range. Vforce is a waste of $$$$$$.

BCB

 

kevinm7

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• Jan 15, 2013

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BackCountryBob said:

Cold engine. Pull plugs, hold throttle wfo, pull 3 x and check.
125 is good.

Had Boysens and switched to the oem softer--much better mid range. Vforce is a waste of $$$$$$.

BCB

Click to expand...

This is what I did. I tried it first pulling it over about 6 times but the needle didn't move after 3 pulls. I then did 3 tests on each cylinder pulling 3 times holding WOT. Thanks for the input on the reeds. I will be inspecting tonight.

 

B

BackCountryBob

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• Jan 15, 2013

• #9

The higher the elevation=softer petals. Reason: Leaner air = less vacuum and the 800 only has the power of a 550--3% loss of power per 1,000 ft of altitude gained. 8,000'-2,000'=6,000 x 3% = -24% hp. loss
(no power loss for the 1st 1,000').

BCB

 

Last edited: Jan 15, 2013