No name chopper

mclothier3

mclothier3

New Member
#1
#1
Hi all,
As promosed this thread is gonna be my build log, this thing wont get done overnight, but I plan on updating as often as possible.

Ok so I happened across an old mini bike frame that I bought from a friend, its pretty much bare, but I found out that it appears that it was manufactured by Bird.

My plan is to rebuild the bike to my tastes into a chopper, the rear tire is gonna be a 205/50-10, front tire is a 16" bike tire, engine will be an old 4hp Briggs I pirated off a Monkey Wards tiller, which will need rebuilt. I would also like to convert it to a different carb, something like a mikuni or similar and buy or fabricate a motorcycle style fuel tank.

Parts of it will be fabricated by myself, other parts will be bought, one main question I have right now is that it looks like I will be running a jackshaft, what are the pros/cons of using a 2-speed jackshaft, are they hard to setup or get the gearing right? reliable?

Anyways here is what I have to start with...


And this is what it looks like with the engine sitting in place...


As you can see there is not much there, I wont be using much of the original frame at all by the time Im done, I will have to fabricate a whole new backhalf to fit the tire.

Since this is going to be a chopper, I needed to build some chopper style forks...


So at this point Im working on the front forks until the rear tire/wheel gets here.
 
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J

jimh

#2
#2
Should be a cool ride. The main benefit with a 2 speed is takeoff. In high they're pretty much like the single clutch setup. In low they're twice as low. They get you moving a lot quicker. You can go up or down in teeth on the sprocket that drives the rear wheel to get the right gearing. You have to have a 3/4" crank for the double sprocket clutch, and I've only seen them for the #35 chain. That frame should make a nice chopper. Forks are looking good so far:thumbsup:
 
mclothier3

mclothier3

New Member
#4
#4
Jim,
yes my 4hp has a 3/4" shaft so its all good. Do you know if they actually "shift" or just progressively accelerate?

And Yellowhand, I took one look at the frame and the first thing that came to mind... this thing is dying to be made into a chopper.
 
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jimh

#5
#5
They actually shift. You should feel a shift and notice a drop in rpms when it shifts, unless you're really on the throttle. Then you'll feel the shift with less noticable rpm drop. I agrre with your thoughts on the frame. The way the bike originally set, the engine plate was tilted forward. When you rotate it back to where it is level, you add a lot of rake to the neck.:thumbsup: A chopper waiting to happen.
 
mclothier3

mclothier3

New Member
#7
#7
Jim, cool! I was hoping it worked like that.

Dobber, neat idea, but the Rupp Mafia is gonna put the hit out on you if you chop that thing. :hack: :hammer:

BTW, I need to come up with a name for this thing, I may hold off till its closer to being done and showing a little more personality. I do think I would like to have it old school pinstriped with a big Rat Fink on the tank.
 
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dobber

New Member
#8
#8
I am not using that frame, that was just a pic to give me what it may look like. I am using a 1970 rupp enduro that I had to have straightened, I need the Seat Pan off of it to fix a rust problem on my 1972 Rupp Roadster2. So the Rupp Guys have to understand that it is a worth while sacrafice.

Kelly
 
mclothier3

mclothier3

New Member
#10
#10
Thats one thing I havent been able to master, I can draw, sketch and paint, fabricate stuff, painted plenty of cars and trucks in my past life, but I never mastered the airbrush.

Who knows, maybe Ill give it a shot myself? If I cant handle it there are a couple here local that do killer airbrush work. :grind:
 
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