What causes a broken skirt?

G

Gary Kamstra

New member
Joined
Feb 25, 2011
Messages
10
Age
55
Location
Hudsonville, MI
Wondering what would cause the skirt of a piston to just break off? What do I do so it does not happen again? Sled has 8000 miles on it with no engine work or modifications done to it.
 
sleddineinar said:
Pistons wear out in the cylinder and slap around too much causing the skirt to break off.
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X2 - assuming you're talking about your SX and not a cast iron bore.

Have you had the sled since new and if so, what was your storage regimine?
 
snomofo said:
X2 - assuming you're talking about your SX and not a cast iron bore.

Have you had the sled since new and if so, what was your storage regimine?
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yes it is my SX and I am second owner, has been stored in a trailer and a shed. I believe the cylinder walls have the nikasil, are you able to hone those at all?
 
Gary Kamstra said:
yes it is my SX and I am second owner, has been stored in a trailer and a shed. I believe the cylinder walls have the nikasil, are you able to hone those at all?
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You'll get many different takes on honing plated cylinders but IMO just scrubbing them with a scotchbrite pad to take some of the glaze is all that's required provided there is no chipping/pitting.

I've yet to see definative proof of what's required to go beyond 5k miles before pistons wear beyond thier usable life which is why I asked about how your sled was stored.

IMO - checking at 5k for clearance issues if for no other reason but piece of mind is worth it let alone the damage a broken skirt can cause.
 
Just found out my 600 SX had a skirt break off as well. Looking at a top end rebuild provided the piece that broke off didnt destroy the jugs or get lodged in a bearing in the crank somewhere. Mine had 6100 miles on it when this happened. Tomorrow the repair man will pull the jugs to check it out. Starting to wonder if it is even worth rebuilding a 97 SX 600 with 6100 miles on it!
 
raptorman2fast said:
Just found out my 600 SX had a skirt break off as well. Looking at a top end rebuild provided the piece that broke off didnt destroy the jugs or get lodged in a bearing in the crank somewhere. Mine had 6100 miles on it when this happened. Tomorrow the repair man will pull the jugs to check it out. Starting to wonder if it is even worth rebuilding a 97 SX 600 with 6100 miles on it!
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sure its worth it, likely the sled has never had a set of rings installed in it. What happens is the rings lose tension over time and they dont support the piston as well. The piston begins to rock slightly back and forth in the bore, this wears the skirts and allows more clearance to rock even more. Eventually the engine will will exert enough force on the skirt(usually always the intake side) to break off the skirt. The pistons in the redhead motors are a cast piston, they wont take as much abuse as the powder forged units of the srx/viper engines. Really to keep the broken skirt problem from visiting you, ya need to freshen up the rings around 2500-3000 miles. lots of people run them longer and dont have problems, but a 2 stroke is hard on the piston rings because its doing 2 times the work of a 4 stroke. Thats why we dont have 2 cycle cars, the engines are lighter and make way more power for the given size, but the engines need service at much sooner intervals then a 4 stroke does.

if you do some searching youll find all kinds of information here on this.
 
my redhead overheated soo the head turned orange an wouldnt shut off pulled plugs an still wouldnt shut off had to keep puttin oil in the cylinder til it did replaced all my gaskets an 3000 miles later she still has 140 psi in each an has seen 2 chassis seems like some jus wont stop an some jus pop
 
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