Dragon Down again

[skibreeze]

Got about 800 miles on it with a PCV w/o any issues, 3000 miles total. Ended up bending the PTO end of the crank and had about 200 miles on it after fixing that. Egts were the same afterwards, so I know that it wasn't an air leak and the reeds are good. I wasn't riding it the day that it went down, but apparently the egts weren't flashing for over temp. I had the pistons swain tech coated. There is no scuffing on the piston sides, but the edges of the piston are eaten away as well as the rod bearings. The plug that is readable is a nice dark chocolate brown. Is this just pure deto from fuel, or is it on the edge and I went over it?

Pic of the good PTO piston

The bad MAG, you can still see the gold Swain Tech coating on the top.

 

[jgd]

This sled is boosted? (looking at your sig)...

 

[skibreeze]

No, my Pro is. The Dragon just has a SLP pipe and can and PCV.

 

[modsledr]

the way the edges are damaged it sure looks like detonation...

 

[skibreeze]

I agree, the plug was not very tight. My question is it from fuel or just a touch too lean? Haven't changed fuel settings in a while.

 

[Mag]

That's just plain ugly, it doesn't look like it was lean burnt to me but I don't know that much about coatings. Are those oem single ring pistons that you had coated?

 

[skibreeze]

I think it may have been lean, but I have ridden it for 800 miles with the PCV. I doubt that it was fuel as there were 3 sleds running from the same fuel. Yes, they were stock coated slugs.

 

[theshadowrider]

When was your filter last changed? Maybe plugged injector? The side that went down maybe you had an injector problem causing that side to go lean.

 

[skibreeze]

Filter was new at the beginning of the season.

Now, to decide whether to just sell the chassis or spend another grand to put it back together. Parting it out is kind of hard to do based on it's overall condition.

 

[AKSNOWRIDER]

the way the edges are damaged it sure looks like detonation...

x2...maybe a bit of water in the fuel? it picked some up at a critical time in a full throttle run?ski, any time it missed, hesitated, bogged before it went down?

 

[2XM3]

This is something you should check..look very close at all your crank bearings we have had the stamped steel bearing cage go and as the little metal particles migrated to the chambers it first appeared just like your piston looked on top, we all figured it had detonated but I noticed some crap in the reed cage and by chance tried a magnet on it, whoooo it picked up the particles. I'm assuming when your crank was fixed they changed ALL the bearings not just the pto side?? We were amazed that it had eaten away the edges of the piston like yours did. Plugs looked great, egts dead on,skirts also near perfect. Just a wild guess but ya can't be 2 careful.

Also check all the oil sprayers if the bearing cage went, as they plug really easy if a bearing got hurt, interesting to note the original bearing on ours that went was a cheap bearing, the replacement I recieved from polaris was a much higher quality FAG German bearing, so they changed the pto bearing brand as they probably had problems with the original type.

 

[skibreeze]

AK, I wasn't riding it the day that it went down.
2X, haven't pulled the motor out yet, but I'll definitely look at the bearing cage.

 

[skibreeze]

Finished pulling the motor, apparently Osama isn't the only one who died on Sunday. Found a broken motor strap and a hole punched in the bottom of the case. Will be parting it out, let me know what parts you want.

 

[theshadowrider]

Finished pulling the motor, apparently Osama isn't the only one who died on Sunday. Found a broken motor strap and a hole punched in the bottom of the case. Will be parting it out, let me know what parts you want.

So do you think the crank failed causing damage to the piston then? What caused the hole in the bottom of the case? So you are going to part out the entire sled?

 

[skibreeze]

I am guessing that it deto'd, pounding the piss out of the brass bushing. The pieces of bushing and the excess play in the rod allowed it bust the case. Parting it all out, 9 pms on parts already.

 

[2XM3]

Damn sorry to here that, I really hate these motors....

 

[Hawkster]

I know just enough to be dangerous with a wrench , and I don't understand is that dog crap brown build up on the pistons and plugs of these engines ? They call that normal ? Can somebody explain what's with the color ? I haven't seen it on any plug chart ? I haven't seen it on any two stroke plug and piston . What am I not seeing ?

 

[DragonSlayer1]

Finished pulling the motor, apparently Osama isn't the only one who died on Sunday. Found a broken motor strap and a hole punched in the bottom of the case. Will be parting it out, let me know what parts you want.

Mine did the same thing. Pistion looked just like yours. I attribute it to polaris excellent motor manufacturing capabilities.