Odin,
You going to pay to repair my bike if the engine comes apart???? I don't think so. Also, Rick Ritter sees these engines every day, and I think he might know a little more about them than you do. How many 400's have you had? I know a guy who has a '95 Sportsman 400 who has never had to do anything to his quad, but I consider him lucky. I might be as lucky, but I run mine pretty hard and with Honda guys a pretty good bit. The last thing I want happening is my engine coming apart on a ride. I believe I can change this piston without removing the engine, and at the same time, will get to see how everything has been doing in the engine. A few hours and bucks later, and I should have a good engine(let's hope I don't drop a circlip into the crankcase). Rick did say that my piston was better than the older ones, but he also said they still have problems out of them. He said that dirtwheels came to him to do some mods to a 400, and that when they tore down the engine, the factory skirt was cracked. Wonder how much longer that would have run without breaking off the rest of the way? Alot of people I know would just run the thing. I guess I'm just different, but I don't think I'm the only one.

 

I have owned 2 stroke Polaris 400's for 5 years now. If you want to mess up your new machine go right ahead.

95 Sportsman
95 Xplorer
99 Xplorer

Total milage between three all quads 8,000 + miles with no engine failures imagine that.

Wiseco pistons will rattle your teeth out before they warm up and expand to normal bore size. So when you destroy your perfectly new quad with a COLD seizure you will know why.

 

Odin,
I apoligize for jumping to conclusions. It's just that there are alot of 15-year-olds who get on here who know everything.
Maybe I can ask this next question without sounding like a smartypants: have you had very much experience with wiseco pistons? This is a sincere question. All that I'm trying to do is set my quad up to last for a really long time without any reliability issues. Murphy's law almost always applies to me. With your experience with the 400, I would appreciate any additional input that you have. Such as how you run your bikes, any other problems you've had, etc. Sorry I spouted off like I did. Thanks,

Waylan

 

Waylan,

You may want to go to Deja.com and research the rec.sport.snowmobile threads regarding Wiseco pistons.
The posts are numerous. You may be able to formulate a good opinion from the experience of this vast array of two stroke users and tinkerers.

amsnow.com may also give you some good pointers

Most snowmobilers have a lot more experience with cast vs forged pistons than us average atvers.

One interesting item which I have noted in all piston discussions: People who sell Wiseco pistons for a living defend them, whereas the failures and real life experiences are reported by the consumers. Hmmm.... another piston sale? Just a little food for thought.

 

I have heard of only one instance where a 400 engine went south while under warranty. The oil injector hose banjo fitting wasn't properly tightened...well the rest is easy to fix. Polaris gave the guy a factory remanufactured engine, and gave it a 6 month unlimited mile warranty on it. Far as I know still going. If it was mine, I would leave it stock while under warranty, as any warranty problems I ever heard about seemed to be fixed to customer satisfaction AS LONG AS THE DEALER STOOD BEHIND THE CUSTOMER. If the dealer doesn't seem like the type to want to go to bat for you, do what you like, otherwise leave it alone. If you run it the 6 months, chances are it will only need a hone job, which runs between $50 & $100 out here. By then you would have experience with the machine & could decide if you wanted a porting job done. After owning my 400 for a year, I would like to give it a little power boost (got a neighbor with a Grizzly that makes me sweat sometimes), but it will have to wait for better economic times for us farmers (don't get me started on $1.54 a bushel corn - same price it was in 1953, or was that 1963). Just a thought.

 

I researched back in 97 on everything that was possible in the modification dept before I bought my 98 400 Scrambler. Even back then everyone who REALLY knew these engines said, if your raising the compression go w/ Wiseco piston, period. Although I have never heard of the skirt being a problem unless excess slop between piston & cylinder occurs from cold siezure, wear etc in which case any quad would crack a piston skirt like my friends have done on their LT250 or 250R. The only slight bad thing I heard about Wiesco is that the rings wear out way faster than stock but this is also good cause you want the rings to wear instead of the cylinder anyway. It's just that it's been recommended to me to change the rings once a year w/ the Wiseco piston or at least check them. I must say from my own experiece, I think an engine in stock form, the stock piston is very reliable & can take allot of abuse & still run great. I overheated once where it shut down, disconnected the override & road many miles a second time overheated w/o any water in the radiator, cold siezed it twice where it also shut down, finally after 2 1/2 years of abuse & VERY hard riding I finally checked the piston to cylinder clearance & there was about .020 overall between piston & cylinder & the darn thing just kept on running REALLY great. My friends LT250 would have crapped out LONG before all of this abuse. My cylinder is now at HPD for porting w/ the HPD cool 12:1 head & Wiesco piston although I would have loved to go w/ Ritter except it was easier to stick w/ HPD since I'm working thru my mechanic who deals w/ HPD. I know of a couple other guys who REALLY beat their 400 Explorers for 4 years now & have never done a thing to them & I'm not sure if they ever even washed them off more than a couple of time or even greased them & they just keep on running strong.
Jim Maloney 98 400 Scrambler

 

No problem, I'm sorry too its been a bad morning.

The new Wiseco piston has a smaller diameter when cold and until the engine reaches optimum temperature will rattle in the bore. Be carefull not to use full throttle until engine is fully warmed up. The piston rings could wedge in cyclinder bore and lock up your engine. This is called a cold sesizure.

If I where you I would just wait another 5 months and then tear down your engine. Talk to Mike Chero and Jack Schultz they are the masters of the 378cc Fuji. Both of these men have hopped up machines. Mike even races his, they both have web sites. Ask these men your questions on HP upgrades. I left my engines all stock. The 378cc is one of the best Polaris engines.

I have many friends with over 7,000 miles on the original engines. The PVT buttons in the drive clutch will wear out before the engine will. Good luck.

 

I am kind of like Jim, I have a 94 400L and a 95 Scrambler (the first year they came out with them). The 94 I use to plow dirt, snow' haul logs, elk and anything else I can. It is bone stock and has never given me any problems the motor is still very strong. On the 95 after about 8 months old I milled the head to bring up the compression. I did not change out the stock piston or rings. I ride out at the dunes quite a bit with it both with stock tires and paddles. This motor is also still running very strong. In fact I can take a 400ex which has a rev kit and pipe very easy up hill or in drags. Dont know what all the hub-ub is about the skirt breakage but I know tht my two 400's have been very reliable.

 

relax Odin, walexa is rebuilding his own bike, not yours!

I've got two buddies with 400's, one is a 97 the other a 98 and both have had broken skirts. We're maybe talking 4,500 miles combined, both bikes! I have also heard of this problem from other 400 riders so I wouldn't say this is an isolated problem.

 

Heres my 2 cents: Change over to the Weisco piston and just let your motor warm up for a couple extra minutes before you ride. I always let mine warm up at least 3 to 5 minutes. Never had a problem...