Anybody into mini-bikes?

I mean the old school tubular frames with 6" wheels and a horizontal lawnmower engine.

Bought a DB 30 for the boys, made in China. With the stock 2.8 HP motor and a weak clutch, I can barely get it moving, but it launches like a rocket with the boys on it (short run in the shop).

At the price of $199 at Joes, it was hard to beat as a starter platform. Been doing some research on them, and apparently it is an easy mod up to hold a 6.5 HP Honda clone engine using a plate that attaches to the stock mounts and the engine and an upgraded clutch. I'll also add a front brake, as all it has is a disc rear brake at the moment.

I think I'll keep one stock for the boys, and mod out another for me so that I can keep up with them.