Any truth to the rumor of older 350L's and 400 two strokes regularly dropping piston skirts hence, breaking crank cases? I have an older model that I bought new a long time ago still running strong on the original piston. Should I consider boring + a new .030" over piston/rings as a preventive maintenance measure?

 

I know of one 350 L that went 6100 miles then the piston sqirt broke and so on and so on I would say yes do it before it cost more to replace the motor its realy not that expensive to do.

 

I have a 96 sport 400 bought used. Actually bought it for my 16 yr old son to ride.. Have had it about 3 months now son rode it the other day and it just quit.. Got it home pulled the head and jug and low and behold broken piston skirt. Looks like the last time the top end was done it was just honed and a new piston popped in. .20 clearance between piston and wall book says .10 max Havent checked to see if the case is cracked hope not!

 

Beleive it or not the most 2 stroke piston failures I have seen is from not filling the oil tank! The second is from cold seizure, running the heck out of it before it warms up. Mostly on liquid cooled engines because the piston expands faster than the barrel.

 

My step dad has a 92 350L. Still running strong. I have heard that the stock piston in some Fuji engines (Fuji is the maker of Polaris quad engines) are weak. Lot of people replace them with a quality aftermarket one before it has a chance to ruin the engine.

 

That's what Rick Ritter told me, change it before
it takes the motor south. Just haven't gotten around to it yet but one of these days I'll put in a Wiseco. I've got to do 2 of them though!

 

I was told that weisco pistons normally have a slight knock sound to them. I have heard this on other machines and my fresh Weisco is doing the same. My friend has a race car with Weiscos and they have the same sound. Any thoughts?

 

Jad, I wonder if the sound you hear is piston slap. I have noticed that Wiesco piston skirts seem to be thinner and don't have support ridges built into them like some OEM pistons. Could be your machinest set it up a little loose.

 

It's a brand new machine it is not loose.