Pistons: single vs normal?

[Rinox88]

Im doing a rebuild of a honda cr250 2000 and looking for piston and cobrod kit when i saw a single piston? Its shorter with 3 rings... will you need a longer conrod when using single? And whats the ups and downs com paired to a bormal one?/? Still deciding between ProX ans wisecon piston and conrod...

[LiamRM212]

I'm not fully sure what your asking? If you are just changing a piston you should not have to change the piston though.

[05CRF250]

I think your confusing a crf 250 piston with a cr 250 piston.

[YZ2Smoker98]

A shorter piston and three rings indicated that's a CRF piston. That is to be used in a four stroke bike. NOT a two stroke.

[Beau 88]

A 2000 model Cr 250 has a double ring anyways , One reason i like my 01' better than the 05 i had , i just believe it's a better design and that extra ring isn't going to save that much weight . ?

[Beau 88]

If you need to save cash but still do it right , here is a kit i found thats cheap and you can pick your piston manufacturer and yes i use NAMURA pistons  ? ? . http://www.ebay.com/itm/181359978516?_trksid=p2055119.m1438.l2648&ssPageName=STRK%3AMEBIDX%3AIT

[The Spanky]

I run a single-ring Wiseco Racer's Choice in my KX250. I also pay the extra few dollars for the TiN-coated ring, so the ring actually outlasts the piston. The reduced drag makes the engine noticeably snappier.

 

OEM pistons for 250 two-strokes are two-rings.

 

If you're looking at a piston with three rings, it's for a four-stroke.

[The Spanky]

A 2000 model Cr 250 has a double ring anyways , One reason i like my 01' better than the 05 i had , i just believe it's a better design and that extra ring isn't going to save that much weight . ?

 

 

A single-ring piston isn't about weight savings, it's about reducing friction and drag. But it is lighter as well, because you are also losing one of the ring lands in the piston.

 

You can actually run just a single ring on your two-ring piston and achieve much the same effect, although the extra ring land will make the piston still weigh more than a true single-ring piston.

Edited May 18, 2014 by Chokey

[Beau 88]

A single-ring piston isn't about weight savings, it's about reducing friction and drag. But it is lighter as well, because you are also losing one of the ring lands in the piston.

You can actually run just a single ring on your two-ring piston and achieve much the same effect, although the extra ring land will make the piston still weigh more than a true single-ring piston.

I read somewhere the 2 ring design will steady the piston better and reduce piston slap after the cylinder has some wear ? Idk I get the friction thing and again don't see a problem , with proper jetting , good oil being used and good coolant .

[Beau 88]

Found this one also i may pick up as a spare unless you need it , http://www.ebay.com/itm/251534218960?_trksid=p2055119.m1438.l2648&ssPageName=STRK%3AMEBIDX%3AIT

[717 MOTORSPORTS]

I read somewhere the 2 ring design will steady the piston better and reduce piston slap after the cylinder has some wear ? Idk I get the friction thing and again don't see a problem , with proper jetting , good oil being used and good coolant .

Probably heard from the same dummy who said namura pistons were ok

[Beau 88]

Probably heard from the same dummy who said namura pistons were ok

I happen to like namura pistons  ? when i replace them or do my top end service they usually still have the moly coating on the shirts with 40-50 hours on them. I will NOT run a dirty air filter or an egg shaped cylinder though , or maybe i just get all the good ones and everyone else gets the bad ones  ?

[The Spanky]

I read somewhere the 2 ring design will steady the piston better and reduce piston slap after the cylinder has some wear ? Idk I get the friction thing and again don't see a problem , with proper jetting , good oil being used and good coolant .

 

 

The piston is still the same length, so stability wouldn't change.

 

There is less metal in the crown though (only one ring land to reinforce) and less drag than two rings.

[The Spanky]

Probably heard from the same dummy who said namura pistons were ok

 

 

Coming from the dummy that thinks there's something wrong with Namura pistons.

Edited May 19, 2014 by Chokey

[MaybeMe]

Well yeah, it's the piston manufacturer's fault, not the guy that ran the bike with an airfilter that had a hole in it.

Edited May 19, 2014 by MaybeMe

[Beau 88]

Well yeah, it's the piston manufacturer's fault, not the guy that ran the bike with an airfilter that had a hole in it.

Or never gapped the rings in a cylinder with 500 hrs. on it