Post by: cnrcpla on October 24, 2012, 12:05:51 AM
Post by: beaner on October 24, 2012, 12:31:09 AM
Post by: cnrcpla on October 24, 2012, 12:34:59 AM
Post by: beaner on October 24, 2012, 01:00:00 AM
Post by: Jeram on October 24, 2012, 11:07:07 AM
this means higher RPMS are achievable with less stress on the piston, gudgeon, small end, small end bearing, rod, big end bearing, crank pin, crank, and main bearings.
Post by: 2T Institute on October 24, 2012, 10:14:50 PM
I have seen the single ring pistons come up a few times but I have never asked how they affect performance. What are some pros and cons to running a single ring? I have always run a wiseco double ring, but I am kind of curious to see if the single ring has any kind of gain to it, or a longer lasting more durable set up. Any opinions out there?
Question is why wouldn't you run a single ring, there is NO benefit in a twin ring in a race bike. The single ring pegged on centre running through the C port has no chance of 'snaging' in a port tha is down to the finsh on the port window.
There is no difference in weight of single/dual ring the ring and the extra aluminium in the piston roughly weigh the same.Single ring pistons make more top end HP.
Post by: cnrcpla on October 24, 2012, 10:26:21 PM
Post by: beaner on October 25, 2012, 12:55:21 AM
Question is why wouldn't you run a single ring, there is NO benefit in a twin ring in a race bike.
You should be able to maintain acceptable compression levels for a longer period of time if you have 2 rings sealing, with not enough loss in power (increase in drag) for somebody at my level. Once that single ring starts to wear, it's over in a hurry. A second ring would help.
Post by: 2STROKEREVOLUTION on October 25, 2012, 08:33:03 AM
Single ring: less friction = more power
Dual ring: Longer lasting, more stable in bore, 2 rings to transfer heat to the cylinder walls so piston stays cooler.
I don't think any of the benefits were that big either way.
Post by: TMKIWI on October 25, 2012, 08:50:40 AM
I would use what ever the manufactor recomends.
I use a wossner single ring because that is all that fits the tm.
I have read up on fitting the Gas Gas 2 ring piston into the tm but from what I can find the benifits are not any better because of the port arrangement.
So just use what is recomended unless you are about to take on RV or someone similar.
Post by: 2T Institute on October 25, 2012, 09:44:23 AM
Just how much and for how long would it keep compression up? The rings wear at a simlar rate or is the second one there to just pick up the slack somehow? When a ring costs $20 odd and takes an hour or so to replace I don't understand the logic. That keeping a component way past it's life is somehow more cost effective?
Question is why wouldn't you run a single ring, there is NO benefit in a twin ring in a race bike.
You should be able to maintain acceptable compression levels for a longer period of time if you have 2 rings sealing, with not enough loss in power (increase in drag) for somebody at my level. Once that single ring starts to wear, it's over in a hurry. A second ring would help.
Dual ring: Longer lasting, more stable in bore, 2 rings to transfer heat to the cylinder walls so piston stays cooler.
Rings don't help piston rock, and the same person that says that twin rings make the piston run cooler(they do but it's very marginal due to increase in friction as rpm rises) will run 50:1 oil.
A thing to notice is it governed by bore size and rpm. Bigger bore engines will tend to have 2 rings smaller bore single rings.
Post by: Stusmoke on October 25, 2012, 10:22:56 AM
I would recommend it to anyone. I push this little zinger to its limits by the way, it takes the punishment well. Run the Wossner next time your 250 is due for a topend, see how you go. Its probably one of the best pistons money can buy so its quality made. Try it, see how you go.
Post by: beaner on October 25, 2012, 02:08:11 PM
Just how much and for how long would it keep compression up? The rings wear at a simlar rate or is the second one there to just pick up the slack somehow? When a ring costs $20 odd and takes an hour or so to replace I don't understand the logic. That keeping a component way past it's life is somehow more cost effective?
The purpose of the rings is to seal. If there are 2, then it will seal better, for longer than 1. Even if both rings are worn similar to the single, 2 rings will still seal better. If it is sealing, the amount of wear is not important, and you are not using it past it's life.
Post by: 2STROKEREVOLUTION on October 26, 2012, 11:34:28 PM
Rings don't help piston rock, and the same person that says that twin rings make the piston run cooler(they do but it's very marginal due to increase in friction as rpm rises) will run 50:1 oil.
Dual ring: Longer lasting, more stable in bore, 2 rings to transfer heat to the cylinder walls so piston stays cooler.
The rock and heat transfer from 2-rings was what I read on MacDizzy.
What is your point on the 50:1?
Quote
A thing to notice is it governed by bore size and rpm. Bigger bore engines will tend to have 2 rings smaller bore single rings.
Wossner's 380 piston is a single ring, and that is a 78mm bore. Stock and Wiseco are twin ring.
Post by: cnrcpla on October 26, 2012, 11:38:45 PM
Post by: Jeram on October 27, 2012, 09:07:30 AM
Just how much and for how long would it keep compression up? The rings wear at a simlar rate or is the second one there to just pick up the slack somehow? When a ring costs $20 odd and takes an hour or so to replace I don't understand the logic. That keeping a component way past it's life is somehow more cost effective?
The purpose of the rings is to seal. If there are 2, then it will seal better, for longer than 1. Even if both rings are worn similar to the single, 2 rings will still seal better. If it is sealing, the amount of wear is not important, and you are not using it past it's life.
yes but its a matter of diminishing returns.
if you have a ring with a 99% seal at operating RPM, then only 1% would pass through to the second ring for it to seal another 99% of that 1% which passed through the first ring.
I cant remember what the ring sealing factor is but its up there somewhere.
so the second ring is completely useless if you ask me.
The ring is considered past its life once its sealing rate begings to decrease, therefore more reliance is put on the second ring.
Whereas if you put a new ring in as soon as compression begins to drop you can retain maximum performance.
Post by: 2T Institute on October 27, 2012, 09:28:20 AM
The purpose of the rings is to seal. If there are 2, then it will seal better, for longer than 1. Even if both rings are worn similar to the single, 2 rings will still seal better. If it is sealing, the amount of wear is not important, and you are not using it past it's life.
How does a ring seal? It's not by radial tension it's by gas pressure behind the ring. Second ring is just along for the ride, it get SFA gas pressure and normaly requires an expander under it to be even slightly effective with sealing cooling or anything else.
Post by: SachsGS on October 27, 2012, 04:38:58 PM
Post by: Jeram on October 28, 2012, 05:32:56 AM
Post by: _X_ on October 28, 2012, 01:32:03 PM
Post by: SachsGS on October 28, 2012, 02:57:11 PM
Post by: cnrcpla on October 28, 2012, 05:40:43 PM