ESE's works engine tuner

[kel]

If this is a Malossi MHR Cylinder have a close look at the outer Boostports. And at the B Ports.
The Malossi Cylinder I know has a B-Port without a Kicker (because the studs are right where the kicker would be on a modern cylinder). The outer boostport is doing the kicker-work.

No not a Maloosi, and no the 3 x C port (boost ports) are not doing the job of clearing out spent combustion gas under the incoming charge. The C ports are all angled very steeply up to the head. This cylinder has B ports with the hook to do this job.

So I would go on Option C: leave it as it came frome the Box ;-) Perhaps make the liner between the ports a bit shallower but nothing more.

No I couldn't do that. There is so much opportunity for performance gain with these cylinders.

looks like this one https://www.google.com/search?q=Malo...RWZoDu09ITM%3A

Maybe I should have just spent the extra money
Looks like the Malossi MHR II team is as per my option 1. Can anyone tell me what angle those ports are angled up at?

[wobbly]

Kel, I would grind the divider between the B/C ports so that all it does is support the ring,ie only a short bridge with a radius on the front ( inner face )
with both walls perpendicular to the bore C L.
Maybe the rear wall of the B port can be filled to make it perp, if it has a hook now, but I cant see what happens on the front wall of the C port at all,so
maybe you can leave the divider in ,just make both walls perp to the bore CL.
Then flatten the D roof and put the rear wall hook into that.

[Flettner]

I'm struggling to see how a piston moving through a ring fixed to the bore is any different from a piston with no ring in a cylinder with no ring, as in model engines.
As I understand it, rings on a conventional piston force outwards on the bore, providing a seal that the piston alone is incapable of providing, given tolerances to allow for expansion differences etc. etc..
It seems to me that a ring sitting in the bore would similarly need to be forced inwards on to the piston to provide the equivalent seal.
I can't see how this is possible without the piston crashing into the ring as it returns to the ring which has sprung inwards while the piston was elsewhere.
And then there is Harry's suggestion/hint/teaser that the piston doesn't touch the ring(s) anyway...

The ring is stationary, no inertia no matter what speed. Gas pressure would still be able to squeeze the ring in, like normal just the other way round, could even be small holes from combustion chamber to the back of the ring? Maybe. Ring would have to be well supported so it can only move in "a knats cock" smaller than the piston when the piston is not there. Could it be any worse than in our normal engines with the ring bulging out of its groove every time it passes the exhaust port. Twice every cycle the ring has to be shoved back into it's groove by a small champher in the exhaust port, the ring in the side of the cylinder wall would have to move less than that. Latest ring technology has it that there is not much spring pressure (movement) in the ring when its loose on the piston, out of the cylinder. I know it sounds crazy but what else?
If the rings never touch the piston, then they are not piston rings

[wobbly]

So now you are going to put Nicasil on the piston skirt to take the sealing load of the gas compressed ring.

[husaberg]

I can remember the actual figure, but engine friction rises at a cube or square to engine speed.
Inertia increases at a square of rpm
So something slippery is at foot.
I think we need to get our lab coats on.

Al-Si-graphite particle composite piston
http://www.sciencedirect.com/science...43164880902598
9% less friction...........
CRC Handbook of Lubrication and Tribology, Volume III: Monitoring ..., Volume 3 pg 165
10% HP increase in passanger an racin car engines
Scuffing resistance increase by a factor of two.
Tested and used in F1

Rods
50% lighter than steel 25%lighter than Ti no bearing.
http://www.mxcomposites.com/faq.php

[Flettner]

So now you are going to put Nicasil on the piston skirt to take the sealing load of the gas compressed ring.

Yes or something better
It's just the same but the other way round

[TZ350]

What is this head ... could it be a variable compression head????? Help Please.

[jonny quest]

Polini made that. It lowers compression as cylinder pressure goes up. Yzr500 had that for one or two years.

I'd like to buy one of these Polini heads if anyone knows of one for sale. Preferably cr125 model

[husaberg]

Polini made that. It lowers compression as cylinder pressure goes up. Yzr500 had that for one or two years.

I'd like to buy one of these Polini heads if anyone knows of one for sale. Preferably cr125 model

Gee that was hard
http://www.ebay.it/itm/111695470713

What is this head ... could it be a variable compression head????? Help Please.

Oh Frits But i would not have been so concise or eloquent though.
The Aprilia was still fairly high. I think either you or Jan wrote is was always generally 16:1 or similar is that right?
Did this vary say higher tight tracks lower open tracks, or was the comp just optimised for the best hp/acceration/over rev compromise at the circuit.

I remember the Poloni power head From Robinsons book did anyone ever use it in competition

Is there anything in the other bits i observed or have i drifted off on a tangent?

The compression ratio was always between 15.5 and 16, optimized on the test bench. No adaption to weather, tracks etc. At least not officially; what individual mechanics got up to, was beyond control. But such actions certainly were not recommended.

Not at Aprilia. I seem to remember that Team Roberts once tried variable comp heads on the factory Yamaha 500s, but the name Poloni does not ring a bell.

I spelt it wrong too i guess "Polini" powerhead

pretty sure the year Wayne Rainey was injured they were using it then.

[chrisc]

Edit: damn you husa!

[Mental Trousers]

Ken, you might like to know that you gave Harry a good scare! For some reason, although he is logged in, he can't see the pictures here. So he could not see the way you were pulling his leg; all he saw was your disturbing text about another competitor.
Mental Trousers, are you there? I promised Harry to bring his problem to your attention. He logs in which seems to work because he gets the message "welcome Ryger" or words to that effect, but he cannot see any pictures and he cannot post anything. The two-stroke world is depending on you, Shane!

Tell him to clear out the cookies in his browser and try again.

What's his login name?

[husaberg]

Tell him to clear out the cookies in his browser and try again.

What's his login name?

I am picking its Ryger
http://www.kiwibiker.co.nz/forums/me...hp/48608-ryger

[crbbt]

The compression ratio was always between 15.5 and 16, optimized on the test bench. No adaption to weather, tracks etc. At least not officially; what individual mechanics got up to, was beyond control. But such actions certainly were not recommended.

are these compression ratios for unleaded?

what was the range for leaded on the dyno?

[Frits Overmars]

are these compression ratios for unleaded? what was the range for leaded on the dyno?

Unleaded has been compulsory in GP-racing for decades.

[Frits Overmars]

Tell him to clear out the cookies in his browser and try again.

Will do, thanks.

What's his login name?

I suppose it's Ryger, like Husa suggested.