# cheep dc motor 7.5-30kw



## McRat (Jul 10, 2012)

I'm a newbie, but here goes:

On Ebay, there are new "4HP" DC motors rated at 24v for $179 US. I bought one for an electric bike starter project, and it appears to be good quality, but I haven't run it yet. In order to get more HP out of it, I will have to experiment with running it at higher voltages. It would be too large/heavy IMO for a pitbike. 

Most RC motors specifically note that they are not for heavy vehicles. They are high RPM, low torque devices. Perhaps with a centrifugal clutch it would work?

30kw is 40HP. A "pit bike" with 40HP is pretty serious, and would require a lot of batteries. Ever rode an aircooled 250cc two-stroke racing dirtbike? That kind of power. Pretty serious acceleration for about 400lb raceweight, IIRC with desert gearing, it would top 100mph in the straight sections. 5kw would probably make a pitbike an animal. 30kw would be "interesting".


----------



## frodus (Apr 12, 2008)

He's going to have more trouble building a pack that can output 30kw than he will finding a motor for a reasonable price.....imho


----------



## McRat (Jul 10, 2012)

I would look on Ebay for a 500w-1000w bicycle motor kits and start there. You'd still be looking at serious money for the battery, but you might be able to pull it off with Sealed Lead Acid batteries. 100 Pounds Stirling? You aren't going to get far unless you find used or free parts.

Right now, Chinese two-stroke motors are in your price range, but the MINIMUM you would need to do 1kW electric using new parts would be about $400 US.


----------

