Top motor mount

[Arnold Layne]

I built two China Girls when I got into them, one rider and one back-up bike. Still haven't used the back-up. It's front mount is for the real wide tube and my aluminum adapter just isn't super rigid, yet it's almost identical to my problem-free (so far) rider. I have been thinking about getting some hex stock about 2 inches long, drilling a hole through the center and threading the ends and using these for nuts on the front cylinder/head studs. Then making an L bracket that bolts to the top of these nuts and the top frame tube, not at all unlike a Harley-Davidson top motor mount. I've got my mounts about as tight as I dare go but it still wants to roll out to the left a little, maybe my bottom mount is too low? Anyway, I think this top mount might work real slick, is anybody running something like this?

 

[MotorBicycleRacing]

I have been thinking about getting some hex stock about 2 inches long, drilling a hole through the center and threading the ends and using these for nuts on the front cylinder/head studs.

Why make them when coupling nuts are an on the shelf item?

I have some 3/8" - 16 coupling nuts that are 1 1/8" long.
Metric are available too but a little harder to find.
Ace hardware should have them.

I have seen a few builders that made a top motor mount before.

 

[2door]

It would help if we had a picture of your current front mount. We might be able to offer some help.

The Harley Leggero comes to mind for a cylinder head mount. The mount was cast into the head.

Tom

 

[biknut]

I think it would be a lot easier, and probably better looking to just fix what's causing your problem.

I've bought a couple of those motors with the wide front motor mount (BGF & LEB). What you may not be aware of is, the rear mount is a little wider on those motors too. It's made to fit 32mm seat post tubes. It's hard to tell the difference without looking at them side by side.

I'm guessing if your seat post tube is less than 32mm, that's a big part of your problem. The two different sizes are interchangeable, so it's easy to substitute one for the other.