I just got my 400 scrambler back from the dealer this week after I scuffed the piston. They bored it 20 over and put a weisco piston in it. Well my brother took it out last night for the first time since i got it back and was on it only 20 minutes and it blew the motor again! What could have caused it to do this? He said he checked the plug before it seized and it was a dark brown so it wasn't running lean. Even if it was running lean i don't think it would have seized only after 20 minutes of riding. He wasn't running it hard or anything, only about half throtttle. He said it sounded like a connecting rod broke so maybe the dealer didn't put it back together correctly the first time? I'm taking it back on monday and see what they say about it. I'm thinking of going to premix and was wondering if you have to have the oil injection blocked off or if you can just let the oil tank run dry and run premix?

 

Could have been a cold seizure??? Did you let the bike warm up to operating temp before taking off? I take it that you didnt give the new piston a little break-in time???

If all they did was bore the jug and drop in a new piston, the rod should not have been messed w/ other than pushing the pin through. Once again, it sound like the classic cold seizure to me.

Keep us posted on what happens

EC

 

Personally, I would want to witness the tear down so I would know first hand what really happened. I have heard of mechs forgetting to do something as simple as installing the circlip in the wrist pin.

???

Greg

 

Did you add oil to the gas tank too, or just let the oil injection take care of it? You should always pre-mix the gas to make sure the new piston gets plenty of lube until it gets broken in. Other than that, I can't see what would cause the motor togo like that.

 

I also would agree with the mechanic error. I have even heard of guys forgeting to put the oil line back on. I sort of doubt that a cold siezure occured. Polaris ATV's are very unsuseptible to cold seziures. And considering that you say that you only went to half throttle, I would highly doubt it.

 

Yes the dealer premixed the first tank of gas

 

#1. Why would you take the oil line off to do a
top-end job?

#2. How are polaris quads unsuspectible
to cold seizures?

EC

 

I called the dealer today to see what had happened and they said I had a hole on top of my piston. They said my main jet was too rich and that was what caused it. I know it will do that if it's too lean but i've never heard of it doing that if it's too rich. Am I right in my thinking?

 

Hey the dealer must be backwards, but to rich does not put holes in the piston.Did they put someone eleses carb on your ride ?

 

Wow, this is starting to turn into a horror story.