Bird Engineering / Sears ???

#1
Guys,
Here's what I think I know about this minibike...
It was built by Bird Engineering, and because it is a 1" frame diameter model, it was sold by Sears, 1970/1973?
What I do not know is the model? The color was red, and it has a very large brake boss, compared to most of the Birds.
I know the engine mount is missing. I'm sending the frame & forks off to the acid dippers to remove the paint & the rust. When I gets back I'll clean up all the tube issues, fabricate an engine mount, & weld it on.
Attached is a picture of the spring front forks
Does anyone know if or how the front forks come apart? I can't see any obvious way, except cutting some welds?
Thanks
BMHS
IMG_5520.JPG
IMG_5526.JPG
 

markus

Well-Known Member
#2
It was a 2 speed version they sold. your info is correct about the tubing size and years made like that.

Hers an example, I think they are model number 80707, the only time you see a good example in a catalog it has the wrong info attached to it. It was a 4hp 2 speed




Sometimes you can take a strap wrench around the coils and get enough to turn the spring out of the tab on one of the cups to get the lower off in one piece.
 
#3
It was a 2 speed version they sold. your info is correct about the tubing size and years made like that.

Hers an example, I think they are model number 80707, the only time you see a good example in a catalog it has the wrong info attached to it. It was a 4hp 2 speed




Sometimes you can take a strap wrench around the coils and get enough to turn the spring out of the tab on one of the cups to get the lower off in one piece.
Markus,
Thank you for the comments. As I disassembled it yesterday, the sprocket was on the left side of the rear wheel, so it did not have a jack shaft. Now, that doesn't mean it did not have a jack shaft originally. So, the 2 holes on the top of the rear brake support brackets were used to bolt on the jack shaft bearing support. That would make sense. How did they get "2" speeds?
Thanks Again
BMHS
 
#4
Markus,
Thank you for the comments. As I disassembled it yesterday, the sprocket was on the left side of the rear wheel, so it did not have a jack shaft. Now, that doesn't mean it did not have a jack shaft originally. So, the 2 holes on the top of the rear brake support brackets were used to bolt on the jack shaft bearing support. That would make sense. How did they get "2" speeds?
Thanks Again
BMHS
Guys,
Does anyone know what the jack shaft looked like. I can measure the bolt pattern, that's easy, but the height of the bearings from the bolt pattern will be a guess. I suppose the only thing I can do is set the whole thing up, before I weld, or machine any of the parts?
BMHS
 

markus

Well-Known Member
#5
Guys,
Does anyone know what the jack shaft looked like. I can measure the bolt pattern, that's easy, but the height of the bearings from the bolt pattern will be a guess. I suppose the only thing I can do is set the whole thing up, before I weld, or machine any of the parts?
BMHS
They were comet 2 speeds, the plates are common and are usually still available to purchase today and not specific to just eh 2 speeds units. they go 2 speeds by using a clutch that has 2 sprockets, those went to a one way/sprag gear and a clutch driven gear on the jackshaft. when the 2nd gear is spinning fast enough to grab is would take over (high gear) and the sprag gear would spin free, when you slow down the sprag picks back up putting it back in 1st gear.
 
#6
They were comet 2 speeds, the plates are common and are usually still available to purchase today and not specific to just eh 2 speeds units. they go 2 speeds by using a clutch that has 2 sprockets, those went to a one way/sprag gear and a clutch driven gear on the jackshaft. when the 2nd gear is spinning fast enough to grab is would take over (high gear) and the sprag gear would spin free, when you slow down the sprag picks back up putting it back in 1st gear.
Thank You!!!!!
BMHS (Brian S)
 
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