I would replace the piston and be safe.The Wiesco is no problem to warm up.I have had one in all my 400s and 250s with no problems.Even with the kids hopping on and taking off with no warm up.Most of the problems are due to setting the clearance too tight to begin with( I set my personal ones .001-.002 and everyone else to .002-.003) and to not breaking in the rings properly.

 

LOL == seems we dug up an old dinasaur of a thread . Did you read the dates on that stuff ? I remember those guys ... LOL I didn't really have trouble with any of them .

I won't register an opinion on this - but I will tell you what I see with great frequency - granted - I work on a lot of 400L's .

1. the older style piston would crack early on . the rings would hold compression , and the piston would hammer itself to pieces .

2. one out of four would break the cases when this happened .

3. the new style polaris piston had smaller intake holes to add material to the skirt - we still saw some that were used a lot breaking within the 6 month warranty .

4. I purchase cases 3 sets at a time for inventory - they are now up to $400 .

Like the Frito's folks say " crunch all you want -- we'll make more"

Decide for yourselves .

Rick

 

garyc660R "Normally Wiseco pistons are a lot less durable than stock pistons. Throw aways designed from moto to moto. Call and check around with other "Polaris Specialists" to make sure Rick just did'nt want to line his pockets a little more. Good luck! "

LMAO !!!!! Gary -- you said that almost 9 years ago ?!?!?!
Hahahahahaha

I honestly laughed .. .

We're cool bud -- LOL -- we're cool ..

Rick

 

Are teflon "skirt buttons" used in the modified engines?

Nitro burning drag engines have used them for years.

 

Mongrol .... No --- I am not a car guy -- I don't know what they are -- please explain ...

Rick

 

I have not seen any in anything but all and all out drag cars. Even then they are rare. If I ran nitro I might run them because nitro tends to really bounce the piston around in the bore.

Rick, they are buttons that are placed around the piston circumference that is counterbored. Some use buttons on the wristpin instead of keepers.

 

Oh yea --- I have used teflon buttons instead of circlips before .

Never counterbored into a skirt though .

New one on me .

Our old 273cc kits for Suzuki quadsports used them . .

Rick

 

If you envision the pattern of a 3 dot pyramid with one dot down near the bottom of the skirt, it will give you a bit of an idea of the concept.

When I built an engine with a "Dyke or Headland" top ring, I would give the piston/wall clearance an extra .001. Then custom fit the buttoned piston to take up the slack.

The pin button and the skirt button would not let the piston pivot or rock (around the pin) and scuffing or cracking a skirt.

The end result being 60% less piston damage, and when the buttons wore down, they were a lot cheaper to replace than new pistons and subsequent damage.

 

I understand . Seems like the cylinder ports in a 2 stroke would not work so well with that type of work . It sure makes sence on your application . Thanks for the information .

Rick

 

I recently purchased a 95 Xplorer 400 from a buddy of mine who had the engine overhauled in Nov 2007.

In Feb the piston skirt broke. The Polaris dealer who did the overhaul said the engine had gotten hot and he wouldn't honor any warranty work. This is when I bought the bike because it was so cheap. The cylinder and head looked OK so a couple of weeks ago I put in a new piston(Namura). She cranked up just fine, ran good and had good compression. The 4th time I road her which was Friday night the piston broke again.

I think I'm going to try a Wiseco this time.