SRX is dead.. opinions for next step

Hey guys finally got time to pull the motor out.. turns out it's not crankshaft that seems fine (for now) just burned down another piston. Which was just rebuilt 300 miles prior and was thought to be caused by clogged pilot jet. I'm going to split the cases and clean and inspect everything and probably have the crank checked since it will be out. Any thoughts on what may be causing this to happen? Carbs were torn apart and cleaned 300 miles ago.
 
Maybe crank seal is leaking? Also when you went through the carbs did you check the screen under the float needle and seat?
 
Not sure.. said he put a Teflon coated piston in there that's all I know. Maybe proX piston??
 
Possibly crank seal like drew said. Check the carbs, maybe they weren't clean enough, also...if that was a wiseco piston, they are know for cold seizures if you don't let them warm up enough before taking off.
 
Good point on the wiseco. My wisecos have the part number on top of the piston. Not sure if all wisecos do but easy enough to look. Also when you go through carbs check the jetting. Never know what could have been put in there. I found a 135 main jet in one of my cylinders when i got my srx.
 
So what's the best way to go on pistons? Wiseco are good as long as you let them warm up?? Or are OEM Yamaha pistons the way to go.. I used wisecos in my banshee and never had an issue. That also never had prolonged runs at 7000-8000 rpms. I appreciate your help guys thank you!
 
cummins6.7 said:
So what's the best way to go on pistons? Wiseco are good as long as you let them warm up?? Or are OEM Yamaha pistons the way to go.. I used wisecos in my banshee and never had an issue. That also never had prolonged runs at 7000-8000 rpms. I appreciate your help guys thank you!
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But do you run the banshee on the really cold days? I second that on the OEM pistons, SPI pistons are supposed to be pretty good too if you don't want to spend the extra money on OEM.
 
those look to be the cheap ones from ebay as it looks from the pic,(not really a good pic) as they have a arrow imbossed on the top. Where as wiseco uses a engraved arrow pointing to exhaust port. also the wiseco pistons have always had the part number on top of the dome of the piston.

From what little I can see looks like a cold seizure on the piston.
 
Please forgive my lack of knowledge.. this happened 18 miles into a ride and after probably 3-4 miles at 60-70 mph. I can get a better picture or 2 after dinner
 
usually a cold seizure will grab all 4 corners of the piston as the piston expands faster then the cylinder does, that's why its called a cold seizure, cant really tell from the pics but that's what it appears as. When they burn down from a lean condition you will notice the front edge of the piston crown to be rounded down and lots of times will melt down to the first ring. Then when the flame front can turn the ring orange and soften it and then it snags the port and gets real ugly.

check the back side of the piston if its smeared its a cold seizure.
 
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First pic is front side, second is rear.. based on you explanation MrViper I'd say that's exactly what happened. Next question is how do I prevent that from happening? Thanks again for your help
 
Did you leave it warm up good before taking off? I always wait for the heat exchangers to get warm before taking off. that looks like an SPI piston
 
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Ya I always let warm up some. Not sure what he put in there for a piston.. didn't realize OEM pistons were so expensive!Wow ha ha
 
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