Piston keeps eizeing when ran hard

[turbowrenchhead]

The first wiseco piston seized three times in a weekend trip up north in 50 degree weather when I ran full bore for 60 seconds. I tore it down and it was a multipoint seize. So the piston clearance was double from .002 to .004. I got it out on the ice this weekend and got it up in 6th and started to run it a little hard and it did it to me again in 20 degree weather. I'm running a 160 main jet. Any ideas? Do I need to go bigger on my main jet? Will moving the needle up a notch help? I'm starting to get very frustrated on this machine. I've spent over 3k on it now and I can't ran it hard.

 

[blasterdemon7]

Have you done a plug chop and a leak down test? Sounds like your lean on your main.

 

[slickerthanyou]

Hey haven't heard from ya in a while!

160 is lean IMO. I was running 162 in warm weather on my 35mm, I'd say you should go up at least two sizes if not a 170 to start. And for sure do a Air leak test first.

Four corner sieze is a classic air leak issue!!! (<<<<experience!)

 

[Prime]

You might want to throw a new piston in there....an obvious giveaway for lean condition is excess wear on the exhaust side of the piston.

 

[best]

Actually a 4 corner seize is typical of piston expanding faster than the bore.
Leaning out may do it, but not allowing enough warm up is the usual culprit.
Forged pistons are the worst, Wiseco are famous for it. Tough piston, but you gotta let them warm up before full throttle.

Seizing in cold weather is another very common phenomenon.
We are very familiar with it with air cooled snowmobiles.
The cold air chills the cylinder and leans the mixture. Runs like scalded cat and then bogs to a stop.
Gotta richen up in cold weather. That high piched screamin' you hear is piston death coming!
Has happened to me. Took out 2 sleds in 20 minutes one beautiful sudden cold day.

What to do? Richen up and let it warm up slowly.

 

[Blaner]

Actually a 4 corner seize is typical of piston expanding faster than the bore.

YES! nailed it there Best. Trick is warming up.

However, a leak test is critical after the motor is assembled, and that 160 is lean, i run a 165 in my 30mm

 

[slickerthanyou]

Actually a 4 corner seize is typical of piston expanding faster than the bore.
Leaning out may do it, but not allowing enough warm up is the usual culprit.
Forged pistons are the worst, Wiseco are famous for it. Tough piston, but you gotta let them warm up before full throttle.

^^^ That is a good point! MY issue probably was both! and a lot of Inexperience!!! I:I

 

[Blaner]

a lot of Inexperience!!! I:I

live and learn my friend, live and learn

 

[turbowrenchhead]

How long does it take before its fully warm? I usally just drive it real easy for at least 10 minutes and then I start getting on it. I posted another tread with more info. I tried fatter jets with no luck. However 180 is the lowest I could get my hands on at the time. I had nothing between 160 and 180. But the 160 still doesn't do much after 1/4 throttle.

 

[blasterdemon7]

How did your plug chop turn out ?

 

[turbowrenchhead]

I haven't been able to do a plug chop. I could of yesterday but I didn't have extra plugs to use. I was hoping that the new jets were going to solve the problem.

 

[blasterdemon7]

I haven't been able to do a plug chop. I could of yesterday but I didn't have extra plugs to use. I was hoping that the new jets were going to solve the problem.

That's what I thought.8-|

 

[best]

I haven't been able to do a plug chop. I could of yesterday but I didn't have extra plugs to use. I was hoping that the new jets were going to solve the problem.

This "modifying stuff" is tricky business. You have to learn all about what you are trying to do or at least follow a reliable formula.
If you jump into the middle of it without understanding it, you will end up lost and likely broke.

After years of doing this sort of thing, I can get a feel for if it is running rich or lean by the sound and the smell of it. Even so, I get fooled occasionally.
A plug chop is not as neat and quick as some make it sound but it is a basic tool for getting your jetting right. Otherwise you pay in pistons.

It is SOOOooo hard to resist a blast of full throttle on a cold engine.
I fight to resist it, especially with Wiseco's in, but you gotta.
5-10 minutes of rolling with slowly increasing throttle.

 

[brandoz28]

This "modifying stuff" is tricky business. You have to learn all about what you are trying to do or at least follow a reliable formula.
If you jump into the middle of it without understanding it, you will end up lost and likely broke.

After years of doing this sort of thing, I can get a feel for if it is running rich or lean by the sound and the smell of it. Even so, I get fooled occasionally.
A plug chop is not as neat and quick as some make it sound but it is a basic tool for getting your jetting right. Otherwise you pay in pistons.

It is SOOOooo hard to resist a blast of full throttle on a cold engine.
I fight to resist it, especially with Wiseco's in, but you gotta.
5-10 minutes of rolling with slowly increasing throttle.

sadly most of us will break a lot of parts while we learn what works and what doesnt!