ESE's works engine tuner

[wobbly]

The best setup is to have the cold water enter the cylinder above or each side of the boost port, this cold flow runs directly across the transfer tops toward the hot Exhaust area.
This hot flow then enters the head above the Exhaust port , crosses the head and exits at the rear , the highest point.
Bleed holes for trapped air need to be added at the cylinder highest point, and if the case is cooled between the gearbox and case , then small bleed holes can cool the Ex underside.

In say an RD/LC/TZ a gasket plate of some sort is needed to prevent the cylinder entry flow from rising directly into the head.

[husaberg]

The best setup is to have the cold water enter the cylinder above or each side of the boost port, this cold flow runs directly across the transfer tops toward the hot Exhaust area.
This hot flow then enters the head above the Exhaust port , crosses the head and exits at the rear , the highest point.
Bleed holes for trapped air need to be added at the cylinder highest point, and if the case is cooled between the gearbox and case , then small bleed holes can cool the Ex underside.

In say an RD/LC/TZ a gasket plate of some sort is needed to prevent the cylinder entry flow from rising directly into the head.

i was looking up something the other day and seen this
i cant be arsed redig them agin but one has the bit with the pockets

https://www.cycleworld.com/story/blo...ing-explained/
https://www.cycleworld.com/story/blo...nd-horsepower/
https://vintagebikemagazine.com/tech...kevin-cameron/

[porttiming124]

Hello everyone.
I'm helping a friend to try and gain power on an old 440cc 2 cylinder snowmobile engine (1979) for racing on an oval track.
This type of engine develops approximately 110 hp at 9800 rpm.
The intake is controlled by a rotary valve.
I am wondering about the shape of the port of admission.
The carburetors are mikuni vm 44 and the port is well round (44mm) all the way to the entry of the crankcase.
Is there an advantage of having a port like the aprilia rsa-rsw (square with rounded corners) for the same area in mm2 compared to a round port?

[husaberg]

Hello everyone.
I'm helping a friend to try and gain power on an old 440cc 2 cylinder snowmobile engine (1979) for racing on an oval track.
This type of engine develops approximately 110 hp at 9800 rpm.
The intake is controlled by a rotary valve.
I am wondering about the shape of the port of admission.
The carburetors are mikuni vm 44 and the port is well round (44mm) all the way to the entry of the crankcase.
Is there an advantage of having a port like the aprilia rsa-rsw (square with rounded corners) for the same area in mm2 compared to a round port?

if you go to part one and two of the ask Jan and Frits about the RSA thread on Pitlane .fr
you will find some discussion about this sort of engine if memory serves.

[wobbly]

The Aprilia RSA later model port was oval shaped with the largest dimension on the RV centerline ie 90* to the RSW.
This narrows the port , and thus reduces the time the valve is sweeping across the port , given the same timings.

[Roflhat]

Measured the exhausts some more, current one is designed to peak at 9.4k, this new one I’m working on should be 10.8k. That’s as high as I can get it with having the standard exhaust fit over it

[Frits Overmars]

if you go to part one and two of the ask Jan and Frits about the RSA thread on Pitlane .fr you will find some discussion about this sort of engine if memory serves.

Thank you for the free advertising Husa. However, googling Pitlane.fr will give the scary result "The domain Pitlane.fr may be for sale...".
You might want to try http://www.pit-lane.biz/t117p246-gp1...-part-1-locked
It may be necessary to register (free) in order to see all the images. And don't be put off by the French language; the RSA thread is mainly English-spoken.

[Roflhat]

Got the pipe finished off, stuck a 115 main jet it the carb. Goes like the absolute clappers now!
Very happy with it, just need to quieten it down a lot. Will put the standard exhaust shell back over it and the stock baffle trimmed down. Hopefully quiet enough, pulled a huge pile of baffles and sound deadening out of the standard pipe

[jfn2]

Frits
On your scavenging concept drawing, you are using a cylinder with 5 transfer ports. Would you change any of the angles for either direction or position and your axial angle formula for a 4 port ( A and B ports and no D port) cylinders? And how about a 2 port ( just A ports and no D port) cylinder, as in some chainsaws? Thank you, Jeff.

[porttiming124]

if you go to part one and two of the ask Jan and Frits about the RSA thread on Pitlane .fr
you will find some discussion about this sort of engine if memory serves.

ok thank you

[Frits Overmars]

Frits
On your scavenging concept drawing, you are using a cylinder with 5 transfer ports. Would you change any of the angles for either direction or position and your axial angle formula for a 4 port ( A and B ports and no D port) cylinders? And how about a 2 port ( just A ports and no D port) cylinder, as in some chainsaws? Thank you, Jeff.

Jeff, this is one of those simple questions for which there is no simple answer.
To start with, I have zero information about the cylinder you have in mind, so I will have to assume that you want to derive it from a cylinder with angles as shown in my scavenging concept, below.
If you omit the C-port opposite the exhaust, I would leave the A-ports as they are, increase the B-ports' trailing position angle from 160° to 165°, increase their trailing direction angle from 132° to 137° and increase their axial angle from 10° to 15°, always assuming that there is sufficient material to do so.

If you want the best solution with only the A-ports, my first reaction would be: "You want to know how much 2 x 2 is, but you don't want the answer to be 4".
There is no way you can approach the scavenging quality of a 5-port layout with just 2 ports. You might increase the A-ports' trailing position angle from 100° to 140° and their trailing direction angle from 65° to 90°, always assuming that there is sufficient material, and decrease their axial angle from 25° to 20°.
But the lack of flow guidance in just two ultra-wide A-ports would not do any good. Besides, the piston ring would object to making the total port width of those 2 ports equal to the total port width of a 5-port scavenging layout.

[philou]

anyone using "Ice" two stroke engine simulator?

http://www.jhis.co.uk/ICE/

I have had the program for a long time and it cannot be installed on the computer. the author cannot solve my problem.

it offers neither the precision and the possibilities of engmod2t.
it only costs £ 25

[jfn2]

Hello Frits;
Thank you for your reply. I did not give you any engine specifics for a reason, I did not want a specific answer. You answered both of my questions exactly as I hoped you would. Thank you.
As to your comment, " You want to (know) how much 2 x 2 is, but you don't want the answer to be 4". I asked my son this question and he, in turn, asked me if it was asked verbally or written down? I answered, written down. He right away, took a piece of paper and wrote, the answer could be 0100. Then he said to me, " The answer is still 4".

[Frits Overmars]

Hello Frits;
Thank you for your reply. I did not give you any engine specifics for a reason, I did not want a specific answer. You answered both of my questions exactly as I hoped you would. Thank you.
As to your comment, " You want to (know) how much 2 x 2 is, but you don't want the answer to be 4". I asked my son this question and he, in turn, asked me if it was asked verbally or written down? I answered, written down. He right away, took a piece of paper and wrote, the answer could be 0100. Then he said to me, " The answer is still 4".

.........

[tdc211]

Jeff, this is one of those simple questions for which there is no simple answer.
To start with, I have zero information about the cylinder you have in mind, so I will have to assume that you want to derive it from a cylinder with angles as shown in my scavenging concept, below.
If you omit the C-port opposite the exhaust, I would leave the A-ports as they are, increase the B-ports' trailing position angle from 160° to 165°, increase their trailing direction angle from 132° to 137° and increase their axial angle from 10° to 15°, always assuming that there is sufficient material to do so.

If you want the best solution with only the A-ports, my first reaction would be: "You want to know how much 2 x 2 is, but you don't want the answer to be 4".
There is no way you can approach the scavenging quality of a 5-port layout with just 2 ports. You might increase the A-ports' trailing position angle from 100° to 140° and their trailing direction angle from 65° to 90°, always assuming that there is sufficient material, and decrease their axial angle from 25° to 20°.
But the lack of flow guidance in just two ultra-wide A-ports would not do any good. Besides, the piston ring would object to making the total port width of those 2 ports equal to the total port width of a 5-port scavenging layout.

Frits. How's that inner radius below the case deck work?
New yz85 is like this. I didn't know what to think about it.