SBT piston destroyed

KK 9

KK 9

Location
United States
Decided to check my compression today (160/160). After words went to start and it pegged wide open. I pulled both plug wires immediately with hesitation. Checked carb butterfly it was closed. So started it again without air filter so I could put my hand over the carb. It started and idled but sounded weird. Pulled plugs one had metal shavings. Yanked off the top end to find this. ImageUploadedByTapatalk1409265646.152244.jpgImageUploadedByTapatalk1409265658.950670.jpg


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KK 9

KK 9

Location
United States
I'm going to pull motor out tomorrow and see if those metal shavings have destroyed anything else. It's a 650 bottom/61x top ported and .5 over. I rebuilt it last year. So after tomorrow I'll decide to go with a 701 bottom or not. What pistons do you guys recommend.


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waterfreak

waterfreak

I had a vision!
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Location
s florida
KK 9 said:
I'm going to pull motor out tomorrow and see if those metal shavings have destroyed anything else. It's a 650 bottom/61x top ported and .5 over. I rebuilt it last year. So after tomorrow I'll decide to go with a 701 bottom or not. What pistons do you guys recommend.


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Click to expand...
go with pro-x pistons
 
kawipilot

kawipilot

Location
Lake Havasu of course
First of all, when your motor "pegged wide open" it ran away, b/c of a lean condition. When that happens, the motor revs out past the rev limiter, probably 9-10,000 rpm+, which is way past what the pistons were designed for. That is most likely when your piston failed. Secondly, the lean condition is a sign that your motor had issues to start with. Tear the motor down the rest of the way, and check your crank. Time for a rebuild...
 
JetManiac

JetManiac

Stoked
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Location
orlando
Not a fan of sbt pistons, but dont think the piston was to blame in your case as others have mentioned.
 
Vumad

Vumad

Super Hero, with a cape!
Location
St. Pete, FL
I have been pleased with pro-x pistons on multiple motors. Last set came from Jetmaniac and have 50 hours on them now.
 
King Kang

King Kang

Never enough tray time...
Location
Cary, NC
Google "lean runaway" and you'll learn why your motor did that. I have a 550 that like to go diesel because of some air leaks.
 
TheBuzzard

TheBuzzard

Location
the jetski grave yard
lean runaway mostly happens when the fuel lines are empty from sitting for days and the carbs run out of fuel before the lines fill up. thats why on initial start up, i stand there with a squirt bottle and feed the motor excess gas until it runs as it should. if it starts to rev, hit it with a squirt of nice oily fuel. quality fuel tank klunks have a check valve in them to prevent the fuel from running out of the lines and back into the tank
 
SUPERJET-113

SUPERJET-113

GASKETS FOR CHAMP BRAP!
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Location
Lake Havasu City, AZ USA
TheBuzzard said:
the top end looks fresh but maybe the same guy that bored/honed it did that hillbilly epoxy/case work so who knows what the clearances were............
Click to expand...

LOL, when I first saw the OP's pic it reminded me of those 62T cases you bought from me on Ebay like 6 years ago or something. Those were Matt_E's first epoxy job... haha :D
 
TheBuzzard

TheBuzzard

Location
the jetski grave yard
SUPERJET-113 said:
LOL, when I first saw the OP's pic it reminded me of those 62T cases you bought from me on Ebay like 6 years ago or something. Those were Matt_E's first epoxy job... haha :D
Click to expand...
that was more than 6 years ago and i was pretty disappointed when i saw that the 2 case halves didnt even have matching #s. everybody says i have questionable ebay sales tatics................ i wonder where i learned that from..............
 
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