Petrol motor conversions (mid mount gearbox)

General Discussion about large electric scooters and motorcycles and other things with no pedals.
Post Reply
slofy   10 mW

10 mW
Posts: 20
Joined: Jan 13 2016 10:18pm

Petrol motor conversions (mid mount gearbox)

Post by slofy » Feb 07 2020 9:41pm

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
Last edited by slofy on Feb 09 2020 12:48am, edited 1 time in total.

slofy   10 mW

10 mW
Posts: 20
Joined: Jan 13 2016 10:18pm

Re: Petrol motor conversions

Post by slofy » Feb 07 2020 9:48pm


User avatar
macribs   1.21 GW

1.21 GW
Posts: 3612
Joined: Jul 22 2014 5:59pm

Re: Petrol motor conversions

Post by macribs » Feb 08 2020 8:01am

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.

slofy   10 mW

10 mW
Posts: 20
Joined: Jan 13 2016 10:18pm

Re: Petrol motor conversions

Post by slofy » Feb 09 2020 12:20am

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?

SlowCo   100 kW

100 kW
Posts: 1416
Joined: Jan 05 2015 5:43pm
Location: The Netherlands

Re: Petrol motor conversions

Post by SlowCo » Feb 09 2020 5:10am

slofy wrote:
Feb 09 2020 12:20am
Am I missing something, I'm wondering why nobody is doing this?
Because it's better to replace the weight of the gearbox and ancillaries with a stronger (heavier) motor and battery pack.

Post Reply