Two stroke V-twin, shared C'chamber?

[apRRentice]

98cc V2-2T made on 49cc Suzuki K50 single, this is what i came across over the net. I know few similar topics discussed here earlier But this time its a running piece to stir up brains again.


Externally it doesn't seem to feature crankcase mods to include separate chamber or offset pins by looking at the cylinder alignment. i could find no further info.

Is it that if the V angle is kept small, would an engine with 'shared crankcase' work though with lesser power output ie., atleast equaling original single?

pics, videos here:http://moppeklubben.se/?p=148

YouTube - Moped Suzuki K50 V-twin

YouTube - Moped Suzuki K50 V-twin

YouTube - Moped Suzuki K50 V twin

YouTube - Moped Suzuki K50 V twin

[greg b]

Theres probably several ways this arrangement could work,but you could be pretty sure the horse power figures wouldnt be to high.I would assume it contains a conrod arrangement simular to a Harley D because the barrels appear to be directly inline with each other,and it contains some form of rotary valve that may also have a system that masks the the transfer ports of the ajoining cylinder,at the right part of the stroke.But then again it may also be just sharing a common crankcase and to hell with the way it performs, and that proberbly explains why he sprayed areo start down the spout of the carby to get it fired up because with that arrangement it would run pretty horrible down low I would imagine with all that cross flow going on.Regards greg b .

[glorybe2]

Originally Posted by greg b Theres probably several ways this arrangement could work,but you could be pretty sure the horse power figures wouldnt be to high.I would assume it contains a conrod arrangement simular to a Harley D because the barrels appear to be directly inline with each other,and it contains some form of rotary valve that may also have a system that masks the the transfer ports of the ajoining cylinder,at the right part of the stroke.But then again it may also be just sharing a common crankcase and to hell with the way it performs, and that proberbly explains why he sprayed areo start down the spout of the carby to get it fired up because with that arrangement it would run pretty horrible down low I would imagine with all that cross flow going on.Regards greg b .

Most two stroke engines require a separate crankcase area for each piston assembly. There is normally a seal that divides the chambers and that precludes the knife and fork style of con rods common in Harleys.
However two strokes do not have to be built with crank case charging loops in the design. It was insane to set up in the past but these days it could be rather easy. In essence build a crank case that is just like a common four stroke case. Supply the air to the fuel injection system by way of a super charger and control the fuel injection so that fuel is sprayed after the exhaust port is covered by the piston.
The drawbacks include the fact that you will need several cylinders in order to have a port open to receive air from the blower at all times and you will probably also need a plenum to store the air charge a bit as well. Such an engine will need one heck of s spin from a starter motor to catch on but once the critter lites up it will surely make a whole bunch of power and rev really suddenly when the throttle is twisted. Getting enough power should be no problem at all but bing able to get that power in a controllable way at all speeds may be a challenge.
Early on the Germans used a super charger with a sort of transmission so that the delivery of power could be controlled. These days an electronic waste gate that limited power until speed was obtained might solve a lot of issues. The last thing that even a drag bike needs is way too much engine power at too low a speed. Two stroke motors can build speed quickly. My old H2 Kawasaki 750cc two stroke motors were rockets and one could easily do a lot more with today's available components. Then again who needs more power than those old machines made? I had one drilled out to about 1000ccs that was insane.

[headsmess]

hmmmm.

with a scratch built engine, having two pins offset by the cylinder angle, so both cylinders share the same timing...

iunno. looks like the usual case of "v-twins are cool, screw the details"

but on the same note... Compact Radial Engines

a friend of mine has some of these radials. unfortunately he wont let me pull one apart! they use some sort of disc/drum induction apparently...

and there was the "puch" design, with two inline cylinders with a common combustion chamber