Petrol motor conversions (mid mount gearbox)

Flame me if this idea has been around for a while, but is using the crankshaft as a gear reduction a good idea?

https://www.youtube.com/watch?v=m3_K-FCK4Mc

https://www.youtube.com/watch?v=Hf31fQJVWOU

What you are after is to use the stock transmission? I would not do a carbon copy of what took place in the bangla workshops. Dirt and grime will find its way into the crank over time...and that one video had some sort of broken metal, forgot if it was the piston skirt or was it maybe the cylinder wall that was chopped off, imagine where it some of it ended up? In the crank likely. Both of those used an open cam chain, that is bound to cause issues?

Personally, I would loose the entire engine and clutch and gearbox. Go for the right electric motor that cover your needs in terms of power, torque and price. Run reduction gear and sprockets and chain to turn the rear wheel. There are so many motors and controllers to choose from these days I can't really see why one would chose to go the bangla route.

Thanks for clearing that up, I was scratching my head wondering why the hell you would keep all that extra weight etc.
I am running a bafang m620 and I like the idea of having gears but coming from a crystalyte 3540 @ 4kw I can see the potential of single speed motors and high speed.

I really want to build an electric dirt bike for jumping. My ideal setup would be mid drive with a mid mounted gearbox, something like the sur-ron but with increased top speed without having to go high voltage or loose too much range. I've seen mid gearboxe's with hub motors and mid motors with hub gears. Am I missing something, I'm wondering why nobody is doing this?

slofy said:

Am I missing something, I'm wondering why nobody is doing this?

Click to expand...

Because it's better to replace the weight of the gearbox and ancillaries with a stronger (heavier) motor and battery pack.