Piston Thoughts

Indy_500 · Mar 11, 2019

Buddys 17 axys went down on us Saturday just shy of 1800 miles. He bought it used with 1400 and put an SLP pipe set on right away. We rode it together 4 days out west thing ripped, rode 1 day in upper michigan, it ripped, and the next day it started bogging. We've been chasing the bog since and tried everything but i had a bad feeling about the motor even though it compression tested at 115 psi. After our ride Saturday he was going to get a leakdown tester but it lost a cylinder with 1 more ravine to hop out of. Anyways, this is the intake side of the PTO piston. Exhaust side is fine and so is the mag piston. By looking at this piston it explains the bog, but do you guys really think it looks bad enough to lose that cylinder? Sure would've thought itd stay running. Thanks

AdrenalineAddict · Mar 11, 2019

Mild scoring like that on the intake side is not the norm (snow ingestion)? Does not look bad enough to cause the performance issues mentioned. How did the bore look? I have found that at 1,600 to 1,800 miles I've always lost performance and generally see a 150 to 200 rpm drop over new pistons and rings.

2XM3 · Mar 12, 2019

Nope :face-icon-small-dis always leak it before yanking it down, theres other issues there

beamslayer · Mar 12, 2019

Did you check Ev cable ?

Detox · Mar 12, 2019

What is the Ev cable?

MKULTRA · Mar 12, 2019

ev = exhaust vavle

Indy_500 · Mar 12, 2019

Just saw everything in person. The piston looks better in person than in the pic. Cylinder hardly has any aluminum buildup/scoring. Why do you guys suggest ev cable? He was going to have the injectors sent out to be tested. What about fuel pump? Obviously the piston needs replacing but getting nervous if we can figure out why it was only running on 1 cylinder

SRXSRULE · Mar 12, 2019

So nothing was tested to figure out why it was running on 1 cylinder? You just ripped the engine apart?

Didnt check for spark, or fuel, or compression?

2XM3 · Mar 12, 2019

hopefully he stuck new plugs and wires on it before taking it apart, could be a simple as a cracked reed or two as well

jim · Mar 12, 2019

Tough crowd. You guys know he is reading this, right? LOL

Yes, you shoulda, coulda done more before tearing it down. But you didn't. So, my thought is that you sucked something into the intake. I don't think it was snow ingestion because I don't see a lubrication failure where you would see some scoring on the cylinder...because no oil and rubbing causes that. The cylinder is clean and the piston, to me, looks to have mechanical scratches because they show very defined scratches. Friction failure, or intake seize, will have way more smearing and damage.

Any rate, I think you sucked a reed into that piston, it made a few cycles and was spit out. So, start there. It is at the right mileage for pistons anyway...so, not a waste. If the reeds look good, look for leaks or suspected leaks. Next would be the electrical stuff...check wires, caps, coils, etc. Lots of possible things...but sounds like a reed.

Indy_500 · Mar 13, 2019

My buddys doing all the work since its his sled, he just asked if i could post on here to get a second opinion. I suggested a reed petal chipped out but he said he thought they looked ok but will give them another lookover. He did try new plugs in the woods and it ran the same. Regardless our season is over since it rained overnight everything in upper michigan where we ride will be concrete.

hamlin · Mar 13, 2019

If the reeds are ok might try swapping coils if he has access to another sled. I had one go bad on my pro and it would randomly cut out a cyl, usually when you needed power the most. Also had one act up on my wife’s 16 Axys.

Indy_500 · Mar 13, 2019

We can swap parts with my 16 if it comes to it

02sedona · Mar 13, 2019

Where is the best place to find a deal on oem axys 800 pistons?

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Piston Thoughts

Indy_500

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AdrenalineAddict

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2XM3

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beamslayer

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Detox

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MKULTRA

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Indy_500

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SRXSRULE

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2XM3

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jim

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Indy_500

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hamlin

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Indy_500

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02sedona

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