making a bike decision

Its fine on the front. The overall weight up there is about the same as a Solex engine. The Solex has the advantage of being lower as it is "split" down the middle so to speak. Keep the Lifan as low as possible and the mount as light as possible. You might consider using bolted aluminum angle. The cost might be a little more, but the weight savings would be good. Lowracer just finished a build using this method. An advantage is the cooling heat and exhaust are blown away from you on the front. For parking at least on 2wheels the engine will try to flop to the left. A simple solution was to drill a small hole through the head tube and steerer and insert a small phillips scerw driver the keep it straight. It rode on a rare earth magnet next to the hole so it was always handy(read not lost). This was not a problem with the later centerstand. Might not be a problem on a stabilized bike. The weight on the front is not real noticible except when pushing the bike around(2 wheels). Once underway goes like a normal bike. I would not recommend it for you given your balance situation unless it is on a trike or a well stabilized bike.

If you could find a good used Worksman Trike that would be great. If you go the trike route. The trike I had worked real well. I was just worried about emergency swerves and it then tipping over. But it was a stock height, read way high! The center of gravity was really up there. If I would have kept it I would have lowered it a bunch.

Good luck which ever way you go!

Terry

It should be able to clear the front brakes especially the old side pull. I would use the Lifan if your domestic situation allows. Should be a power house for years to come, versus wearing out weedeaters. Just take your time and engineer a well designed bike for "everyday" use, then experiment til your hearts content on WE bikes.

The tadpole trikes are more stable, but more expensive and difficult to get in and out of. Maybe you can find one of those worksman trikes with a drum brake on the front.

I understand, considering what happened, why you are leaning towards a trike. It makes sense. But for safeties sake, I would be obsessive and spare no expense to put the best possible brakes you can on a trike. That's a lot of weight to stop. That stability won't do you any good, when grandma pulls right into your path with the Country Squire, if you can't stop.