rotary disc valve

[snorks]

Again , a bit outside the scope of the home tuner but has anyone considered a rotary disc valve for the china motors? Perhaps using the ignition side of the engine. Running the ignition from the primary drive side.
Just imagining a outside the box kind of logic to super tuning these chinese engines.

Cheers
Simon

 

[Theon]

Reed Valve!

 

[cannonball2]

Funny I was just looking at a bare case thinking of case induction through the mag area. It would require an ignition re-engineer as well. A rotary valve would require some serious modding. Be easier to add reeds to the idea I was considering.
I remember when I was in high school(1960s yikes) a friend got a new Kawasaki. We could not figure out where the carb was. Turned out it was inside the engines side casing, I guess it was a rotary valve.

 

[frank66]

that would install on the side usually and the result is terrible crankcase airflow for the transfers and the crank is completly blocking most of the mass air flow/ filling of the case is dfficult at best.

 

[snorks]

Simply not true. Disc valves were used for decades on racing two strokes, by all the big manufacturers! Alot of reed blocks are mounted direct to the case. In a piston ported engine the incoming charge has to travel down the cylinder wall first then into the case...disks can be timed to retard the vacume of the case a few degrees thus creating a rapid incoming charge.

Cheers
Simon

 

[scotto-]

A waste of time and money.....would also take away the appeal of the simplicity of the already refined "China Girl"

How about a big bore kit? A 100cc cylinder, piston and a high compression head.

Can't believe no one has done this yet.....gee I wonder why?

 

[frank66]

well snork/ i love it if it came from the factory with rotory valves. but as an install.... not so much.

im from canada and the snowmobiles here dominate w rotory valves for maybe 20 years or so. they sound excelent too.

 

[frank66]

piston port will make 3hp total unless you can clutch it till 4000rpm. then it could double hp.

reed valve could make 1hp every 1000rpm.

 

[wheelbender6]

My understanding is that the rotary valve will make your two stroke engine torquier, with a little sacrifice in top end power. My Kawasaki 100cc had one and Maico used a rotary valve on its 125cc motocross racer for a while. I think the reed valves have replaced the rotary valves on newer models.

 

[maniac57]

Properly tuned, a disc valve setup can make noticeably more power than a reed valve, but when pushed to these levels, disc valve engines become very abrupt and violent with a huge power hit when it comes on the pipe.
This makes them less rideable even with better power numbers which, along with packaging issues, is why reed valves eventually came to dominate racing two strokes.
But for max output, the disc valve is very hard to beat.