Help Choosing a Piston

[enduro 4 life]

So rebuild time is upon me on my 2013 kx 250f. This is my first rebuild and was wondering what pistons you would recommend? I race top C class motocross. What pistons have been reliable, better performance ect?

 

Thanks, Dan

[eandy]

Go with the weisco man ive never heard a negative thing about them

[tractor 232]

Yep wiseco best out there

[EnglertRacing]

CP > JE > O.E.M. > WEISCO

 

the x forging CP models come with a dlc coated pin

and if you buy the piston from them you can order the option "lateral gas ports" its like 12$ its holes drilled around the perimeter of the top ring land to the back of the ring groove, it allows cylinder pressure to reach the back of the ring quicker forcing the ring out faster.

 

i don't know what the stock Compression ratio is on your bike but

CPKX3051C 14.2-1 compression.   Im not sure you would get away with pump gas on that one..... ask in the kawi forum.

but people run 13.5-1 and even some 14-1 in the crf450s on pump gas.

[NzJohny]

wossner are less known but as good as wiseco imo

[Stealth parade]

I say stay away from wiseco procircuit because they are really je pistons, I reccomend going with a CP piston

[nesc103y]

I have found CP and Vertex to both be very good quality. And they're the same weight as OEM which doesn't upset the balance.

 

Stay away from OEM. I've seen too many shattered from detonation.

[Bmorin237]

You can't go wrong with OEM, and wiseco for sure the only second option in my book!

[Bazuka Joe]

You can't go wrong with OEM, and wiseco for sure the only second option in my book!

Wiseco or oem all day Edited March 30, 2014 by Bazuka Joe

[mxracermx]

Wiseco is junk on these bikes. We use the oem from a 2011 because it's the same compression but stronger. CP or JE are great but I've heard a few folks complain about a change to the bottom end response.

[Bazuka Joe]

Wiseco is junk on these bikes. We use the oem from a 2011 because it's the same compression but stronger. CP or JE are great but I've heard a few folks complain about a change to the bottom end response.

 

care to explain why?? what do you mean by "these" bikes

[mxracermx]

care to explain why?? what do you mean by "these" bikes

because it's not fair to say on all bikes. The 2stroke pistons are ok but here on the west coast motor builders don't use wiseco on thumpers. Their cheaply built and with a full rebuild costing so much why risk it over a piston?

[Bazuka Joe]

because it's not fair to say on all bikes. The 2stroke pistons are ok but here on the west coast motor builders don't use wiseco on thumpers. Their cheaply built and with a full rebuild costing so much why risk it over a piston?

 

I was just curious to your opinion. me, along with many others on here im sure would agree that they are quality pistons, and in fact if not, one of the best aftermarket pistons you can get. I have had great experiences using them in all my bikes ive owned. why ok in 2 smokers but not the thumpers?

[mxracermx]

I was just curious to your opinion. me, along with many others on here im sure would agree that they are quality pistons, and in fact if not, one of the best aftermarket pistons you can get. I have had great experiences using them in all my bikes ive owned. why ok in 2 smokers but not the thumpers?

I know a lot of people buy and run them and have no issues. I have used them in the past in my 2 strokes. Some lasted some didn't. With the compression, rpm and tolerances that thumpers demand I just wouldn't risk it. That's my opinion. Now take some top motor builders that know 10 times more than me, Naveen, Frenchie, Posey, PC, EMT, haseaker just to name a few out here and not one would ever use one. Some use only OEM others have JE or CP make them to their specs. If they work for your riding style and budget with no issues then great! Motors are not cheap. It's just my opinion and what I've learned over the 35 years of riding/racing and rebuilding my own motors. I find here folks ask for input or opinions and some get offended when you give it. Just offering up my 2 cents hope to offend no one Edited March 31, 2014 by mxracermx

[Bazuka Joe]

I know a lot of people buy and run them and have no issues. I have used them in the past in my 2 strokes. Some lasted some didn't. With the compression, rpm and tolerances that thumpers demand I just wouldn't risk it. That's my opinion. Now take some top motor builders that know 10 times more than me, Naveen, Frenchie, Posey, PC, EMT, haseaker just to name a few out here and not one would ever use one. Some use only OEM others have JE or CP make them to their specs. If they work for your riding style and budget with no issues then great! Motors are not cheap. It's just my opinion and what I've learned over the 35 years of riding/racing and rebuilding my own motors. I find here folks ask for input or opinions and some get offended when you give it. Just offering up my 2 cents hope to offend no one

Non taken! I just like to hear reasoning for things that's all, helps clarify things

[MarkMS3]

Is fitting an 11 piston into a 14 bike just as straight swap or do you have to use an 11 rod as well?

[shwety2]

namura pistons are great there like Wisco but cheaper I run it in my 2 stroke and it performs amazing

[FishSticks]

namura pistons are great there like Wisco but cheaper I run it in my 2 stroke and it performs amazing

i wouldn't run Namura they have quality control issues I would go with oem or weisco but oem is better

[nesc103y]

Namura has a large line of pistons for different model bikes. They are ok quality. About as good as OEM.

I would be ok with one in a low stressed woods bike,but I wouldn't use one in a high stress race motor.

[mxracermx]

Is fitting an 11 piston into a 14 bike just as straight swap or do you have to use an 11 rod as well?

same exact piston only stronger around the wrist pin. Next time your at the dealer ask to see both. You'll see where the 12,13 and 14 piston have shaved weight. The 11 is substantially thicker in that area.