Pistons...Weisco vs. SPI vs. Kimpex ??

[skidoodoug]

Getting a rebuild done to a 2000 MXZ 700 but do not know what brand of piston to go with. I can't say money is no option, but do plan on keeping it so...

Suggestions?
Thoughts?
Experiences?

Thanks
Doug

 

[mikedrh]

These kinda posts usually end up with a bunch of very strong opinions and I don't try to get too involed but I just had to throw my .02 in.

Any of the import pistons (Kimpex, Sport Parts, LLP, Groth Products, and several others) are probably all coming out of the same "Vat" in Taiwan somewhere and several companies put there name on the box.

Most of the import piston failures are because the the skirt breaks off. Not that they won't ever work but the clearance is very critical. If you have even a .001" too much the piston rocks in the bore and the skirt WILL break off. If the skirt gets between the crank and the crankcase bad things can happen. If everything is perfect they will "probably" work. I'll never believe for one minute that you can manufacture a piston, ship it half way around the planet, sell it for half the price of any other piston and maintain the same quality.

This leaves you with two choices, OEM or WISECO. And either is a good choice.

I'm pretty partial to the WISECO products for two reasons, they are a forged piston which makes them stronger and they are less money than the OEM pistons.

One thing to keep in mind is the fact that no matter which piston you choose all of them will melt at about the same temp. So if you have a lean burn down none of the above will be any better than the other.

 

[mn_polaris_guy]

These kinda posts usually end up with a bunch of very strong opinions and I don't try to get too involed but I just had to throw my .02 in.

Any of the import pistons (Kimpex, Sport Parts, LLP, Groth Products, and several others) are probably all coming out of the same "Vat" in Taiwan somewhere and several companies put there name on the box.

Most of the import piston failures are because the the skirt breaks off. Not that they won't ever work but the clearance is very critical. If you have even a .001" too much the piston rocks in the bore and the skirt WILL break off. If the skirt gets between the crank and the crankcase bad things can happen. If everything is perfect they will "probably" work. I'll never believe for one minute that you can manufacture a piston, ship it half way around the planet, sell it for half the price of any other piston and maintain the same quality.

This leaves you with two choices, OEM or WISECO. And either is a good choice.

I'm pretty partial to the WISECO products for two reasons, they are a forged piston which makes them stronger and they are less money than the OEM pistons.

One thing to keep in mind is the fact that no matter which piston you choose all of them will melt at about the same temp. So if you have a lean burn down none of the above will be any better than the other.

Good summary.

 

[stevis]

These kinda posts usually end up with a bunch of very strong opinions and I don't try to get too involed but I just had to throw my .02 in.

Any of the import pistons (Kimpex, Sport Parts, LLP, Groth Products, and several others) are probably all coming out of the same "Vat" in Taiwan somewhere and several companies put there name on the box.

Most of the import piston failures are because the the skirt breaks off. Not that they won't ever work but the clearance is very critical. If you have even a .001" too much the piston rocks in the bore and the skirt WILL break off. If the skirt gets between the crank and the crankcase bad things can happen. If everything is perfect they will "probably" work. I'll never believe for one minute that you can manufacture a piston, ship it half way around the planet, sell it for half the price of any other piston and maintain the same quality.

This leaves you with two choices, OEM or WISECO. And either is a good choice.

I'm pretty partial to the WISECO products for two reasons, they are a forged piston which makes them stronger and they are less money than the OEM pistons.

One thing to keep in mind is the fact that no matter which piston you choose all of them will melt at about the same temp. So if you have a lean burn down none of the above will be any better than the other.

Nice job Mikedrh. I agree with everything here.

 

[skidoo50]

I to am going to rebuild my topend and was just doing some pricing. I have a mxz600sdi and this is what I came up with. OEM parts $396.74 less freight Wiseco kit with caged bearings $378.97 less freight. Mine did not burn down but has almost 9000 miles. My thinking is that OEM lasted this long. I should be able to go another 9000 with new OEM. Just my .02

 

[snocrazy]

I to am going to rebuild my topend and was just doing some pricing. I have a mxz600sdi and this is what I came up with. OEM parts $396.74 less freight Wiseco kit with caged bearings $378.97 less freight. Mine did not burn down but has almost 9000 miles. My thinking is that OEM lasted this long. I should be able to go another 9000 with new OEM. Just my .02

Just slap a fresh set of rings in it to freshen it up. I think if you are going that far in with that many miles you should replace the seals in the lower end as well.

Any piston I replace is going to be with Wiseco

 

[mikedrh]

I to am going to rebuild my topend and was just doing some pricing. I have a mxz600sdi and this is what I came up with. OEM parts $396.74 less freight Wiseco kit with caged bearings $378.97 less freight. Mine did not burn down but has almost 9000 miles. My thinking is that OEM lasted this long. I should be able to go another 9000 with new OEM. Just my .02

You should check out www.pistondealer.com for your WISECO stuff, better pricing and free shipping.

 

[trailshredder]

I agree with mikedrh for sure. Although we leave the decision up to the sled owner. On a rebuild we will quote both SPI and Wiseco and guess what....most choose the SPI because of price. So with that said we have a lot of sleds running out there with the SPI piston and have yet to have a problem. On the other hand if it were my sled I would more than likely choose the Wiseco, don't really know why but a gut feeling I guess.

 

[POLARIS TURBO]

Wiseco is a nice piece , although my friend used some spi pistons and no issues so far!!! Budget will dictate your choice im sure!!

 

[mn_polaris_guy]

I to am going to rebuild my topend and was just doing some pricing. I have a mxz600sdi and this is what I came up with. OEM parts $396.74 less freight Wiseco kit with caged bearings $378.97 less freight. Mine did not burn down but has almost 9000 miles. My thinking is that OEM lasted this long. I should be able to go another 9000 with new OEM. Just my .02

Agreed. $20 diff, I'd go with OEM too I think.

 

[skidoo50]

Thanks for the info Mike,they were about $50.00 cheaper

 

[toddspolaris]

The thing with wiseco's being forged they actually swell quicker than cast piston. Therefore the customer who gets on his machine and takes off right away may suffer piston scuffing and cold siezures. I see this a lot on watercraft. We always use cast pistons and have very good luck. can't say in 20 yrs using cast pistons (which are usually OEM) have never had a problem.

 

[indy_500]

Wiseco does have tighter tolerances, so they need to be warmed up GOOD. The way wiseco packages their pistons shows how much they really care. I would go with wiseco. Go on ebay, you can find wiseco w/gaskets for around 275 or without for around 225. SPI is kimpex pretty much. Plus wiseco is made in usa but their needle bearings, wrist pins, circlips, and rings aren't.

 

[mikeh906]

Great post Mike. Indy has it right also. Warm up is critical, but that goes for any sled. If he got 9000 miles so far, he is doing things right. One of the most critical things most peaple do not do is ring gap clearance. The bottom end is a must, and I reccomend having the dealer do it as the grease is very expensive. Also superior tools and knowlage always comes out ahead.[cheaper and right] Another common issue is finding the cause that lead to the burndown, not in this case. Add a few bucks to that budget, now is a good time to go through the whole sled and you will find things. Rebuild the clutchs, new belt so you can break in both at the same time.

 

[indy_500]

Ring gap is really simple. With the cylinders off, place the ring down in the cylinder, and push the piston up from the bottom to "level out" the ring and measure the gap with a feeler gauge. .12 or .012 is what you want i believe (i don't remember which one). You do not put the ring on the piston, just compress it, and push it down the cylinder and measure. If you don't have a big enough gap, just lightly file a tiny bit off the end of the ring Until the gap is perfect. Once you get it perfect towards the top of the cylinder, slide it down to the bottom to make sure ring gap is good down there too.

 

[02zr600]

I to am going to rebuild my topend and was just doing some pricing. I have a mxz600sdi and this is what I came up with. OEM parts $396.74 less freight Wiseco kit with caged bearings $378.97 less freight. Mine did not burn down but has almost 9000 miles. My thinking is that OEM lasted this long. I should be able to go another 9000 with new OEM. Just my .02

thats what we decided to go with too. if oems can handle that many miles without issues, why not go with them again.

 

[coldbear]

Germs vs Chinese

I personally think the Germans make a better product than the Chinese. But the quality comming out of China is getting better.

 

[tealracing16]

Ring gap is really simple. With the cylinders off, place the ring down in the cylinder, and push the piston up from the bottom to "level out" the ring and measure the gap with a feeler gauge. .12 or .012 is what you want i believe (i don't remember which one). You do not put the ring on the piston, just compress it, and push it down the cylinder and measure. If you don't have a big enough gap, just lightly file a tiny bit off the end of the ring Until the gap is perfect. Once you get it perfect towards the top of the cylinder, slide it down to the bottom to make sure ring gap is good down there too.

Ummmm ok....but that is for your engine remember all engines are different.