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A 'piston skirt' 2-stroke engine has the carburetor connected to the cylinder. Intake of fuel is governed BOTH by the piston covering/uncovering this intake port, as well as through induction through the transfer ports. The piston covering the intake port prevents fuel/air mix pushing back into the carb.

A case reed inducted engine has a carburetor connected to the crankcase, and fuel intake into the cylinder is through the transfer ports only. The reed valves prevent fuel/air mix pushing back into the carburetor.

The site you posted is essentially just hyping their stuff - 99% of all the '47cc' bikes are case reed inducted.
 

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Reed valved engines are better because you can use a selection of reeds to tune the engine.

I've never tore my weed whacker apart, but I'd assume that would be a case of the piston skirt design. I'd never heard of that type of motor on a pocketbike until now.
 

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quote
"Reed valve engines CAN be better, but there are more factors than that.

For example, this piston skirt engine:
http://www.davesmotors.com/store/product444.html
will destroy the reed engine of similar displacement found on many '47cc' pocketbikes.
__________________

Haha,I have a 25 cc motor that puts out 2.5 times the rated horsepower of that goped motor.I got one of those 39.9cc reed valve pocketbikes I'll run against that goped motor ;).....

Oh yeah mine dyno's around 15 hp :D an industrial motor is an industrial motor, a true race prepped reed valve motor will leave a piston skirt motor laying around like your dirty underwear.


Tom
 

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Bulldawg racing said:
quote
"Reed valve engines CAN be better, but there are more factors than that.

For example, this piston skirt engine:
http://www.davesmotors.com/store/product444.html
will destroy the reed engine of similar displacement found on many '47cc' pocketbikes.
__________________

Haha,I have a 25 cc motor that puts out 2.5 times the rated horsepower of that goped motor.I got one of those 39.9cc reed valve pocketbikes I'll run against that goped motor ;).....

Oh yeah mine dyno's around 15 hp :D an industrial motor is an industrial motor, a true race prepped reed valve motor will leave a piston skirt motor laying around like your dirty underwear.

Tom
You are absolutely right. A well prepped reed motor is a superior machine.

But remember, factory rated horsepower is only a number. With a full port job and a WYK-58 carb, my personal G43L simply cannot be compared to a stock one. Allow me to add a few more race preps such as a high compression headkit, and I'd be up for a race anytime :)

Or let me swap out my engine for this one:
http://www.davesmotors.com/store/product891.html

There are plenty of 22-25ish cc engines putting out over 5HP, both reed and piston style.
 

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Race preps,mine comes out of the box ,no mods to add,no "rocket keys" to install,blah,blah,blah

The point I was making is you can't compare those two motors,a reed valve motor is much better than a "piston skirt" motor.The yeilds in pure usuable power are much higher in the reed valve motors.

If you want to run the 62cc motor ,no problem I got a 50cc that would probably have a field day with it,there is no replacement for displacement,but comparing those two motors is like compairing apples to oranges.

Tom
 

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Bulldawg racing said:
The point I was making is you can't compare those two motors,a reed valve motor is much better than a "piston skirt" motor.The yeilds in pure usuable power are much higher in the reed valve motors.
Like I said before, you're absolutely right :)
 

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A Picture is Worth a Thousand Words

So two pictures might be worth 2000. Two exploded views are attached; the M-47 47cc reed engine and the M-49 skirt engine, different breeds. The M-47 is strictly for racing, stripped of any any extras that will add weight. The M-49 is commonly used on the midbikes and must supply electricity for accessories such as lights, turns, horn, etc. Therefore it has to have a battery charging supply as well as the battery, lots more weight on the bike.

A 'piston skirt' 2-stroke engine has the carburetor connected to the cylinder. Intake of fuel is governed BOTH by the piston covering/uncovering this intake port, as well as through induction through the transfer ports. The piston covering the intake port prevents fuel/air mix pushing back into the carb.

A case reed inducted engine has a carburetor connected to the crankcase, and fuel intake into the cylinder is through the transfer ports only. The reed valves prevent fuel/air mix pushing back into the carburetor.

The site you posted is essentially just hyping their stuff - 99% of all the '47cc' bikes are case reed inducted.
 

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