front mounted intake

[pocdragon]

hello all!

ive seen a few bikes with the intake swapped with the exhaust, i think this looks alot better and i would like to know how to do it.

is it as easy as putting the jug on back to front?

or is there alot of machining and metal work involved?

CHEERS!

 

[Mr. Minecraft]

It seems that you should be able to.

 

[GearNut]

That is one of bairdco's race bikes.
Here is his thread on his experiment:
The Backwards Engine Experiment, 1939 Colson

 

[bairdco]

i've done it to many bikes. it's kinda my trademark now. i like it better, except for the leg warmer action...

read the thread gearnut posted to learn how...

 

[Ludwig II]

Do you specifically have to match the transfer ports up, or is it a crude enough engine not to notice?

 

[bairdco]

yeah, you have to match the transfers by grinding away at the case if you want it to perform.

norm (2door) did it first, without matching the ports and it worked, but he didn't keep it backwards for very long. i think he just wanted to see if it could be done.

on some motors, you've gotta 180 the piston, too, or the rings will hang up.

then you have to make a new intake and modify the exhaust.

 

[Ludwig II]

Are there any actual heat dispersal benefits, or is it more a cosmetic improvement?

 

[bairdco]

it heats up about the same, but there is a performance improvement. all the motors i've reversed are faster than stock.

there's a lot of different theories tossed around as to why it would be faster.

one, the motor spins counter-clockwise, so it's flowing straight through.

two, the ram air effect. i doubt that comes into play at the low speeds these bikes go, and they seem to run leaner with the carb in front, but i think not having the carb stuffed in the rear behind a hot engine helps. it gets some fresh air, so it should breathe better.

three, since the transfer ports in the case are now twice the size, it gets more fuel mixture, and lubricates better.

i clean up all the ports since i have the engine apart, so i'm sure that helps, just like it would if it's not reversed. but it does seem to run faster.

and cosmetically, it looks bad ass...

 

[pocdragon]

thankyou all for the great information, i have an extra china girl i want to mess around with and i love the design. it just makes sense to me, why were the engines developed with the carb backward anyway?

 

[Ludwig II]

Probably because that side of the barrel is where the thrust face of the piston is, and it runs cooler and is better lubricated. Less of a problem with modern oils, but it was the conventional way of making 2 strokes since nineteen o dead.