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compression 17 Axys 800 pro

ENDO1

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Apr 6, 2008
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Central WA State
What should I see for compression on a 17 800 pro at 1500 ft elev ?
and what is the correct way to do it, Leave one plug in , other plug out at same time. engine warm or cold, ECT ?
Have 2500 miles, still running strong no rpm drop, Just thought I would check, trying to decide on checking new and keeping for spare or trade or possible sell .
 

02sedona

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You should see a 3% loss for every 1000 ft in elevation. Just pull both plug wires, remove one plug to test, install gauge, and hold the throttle wide open when testing a cold motor. Fwiw i get 102/100psi at 6000 ft.
 

ENDO1

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Apr 6, 2008
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Compression

You should see a 3% loss for every 1000 ft in elevation. Just pull both plug wires, remove one plug to test, install gauge, and hold the throttle wide open when testing a cold motor. Fwiw i get 102/100psi at 6000 ft.

Thank You 02Sedona.
So if I am looking at it right, I should be around 115, at 1500 Ft .
 

eyefish123

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I'm about 2200' and was getting 103 psi in each cylinder. I was only getting around 8000 rpm. Did new top end and rpm is back up to 8400. This is on a 2017 Axys and had right at 2000 miles.
 

ENDO1

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Apr 6, 2008
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I'm about 2200' and was getting 103 psi in each cylinder. I was only getting around 8000 rpm. Did new top end and rpm is back up to 8400. This is on a 2017 Axys and had right at 2000 miles.

Did a check on mine , had 115 on both sides,at 1500 ft, I have 2500 miles on mine. Was expecting less, Guess I am good to go.
 

BD-Xtreme

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At low elevation you should have more than 112-115 psi for sure. Should be more like 125-130, but gauges can vary. If you have over 2500 miles, it would typically be down on compression though.
 

TRS

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A Leak down test is the “only way” to get an accurate read of engine condition. Since the implementation of decompression holes, compression tests aren’t as credible.
 

damx

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128-130 psi at 100 feet above sea level is what we get on a 800 axys.
 

danby

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For a proper compression test you have to zip tie the exhaust valves closed. the actuator sits slightly in one direction ( can't remember if it's open or closed some to open the decompression holes). After holding the exhaust valves actuator back it will allow you to properly compression test your motor.
 
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