My Friends Mini Bike I'm Restoring

M

msrfan

#42
#42
If I want to run the big motor, there's a lot of changes to be made. A different base plate welded into the bottom frame rails would just be the start. It's also really wide and I would need to use a longer jack shaft to mount the outboard sprocket.
So I found this monster Briggs race engine a buddy gave me years ago and I forgot I had it. Fits really well and I think I have enough stock components to de-tune it and make it reliable and start fairly easy. DSCN8653.JPG DSCN8652.JPG DSCN8651.JPG
 
M

msrfan

#45
#45
I don't know much about either racing engine other than I'll need to mellow them out and make them pull start and idle. It's nice to have options though and learn as I go.
 
M

msrfan

#47
#47
Thanks to "mjsonny", I have a 6'' wheel with sprocket coming soon. I swapped him for my 5''. While I'm deciding what motor to install I found a Chinese fuel tank that looks okay for now. Made some brackets and used existing holes to mount it. Mocking up a seat next. Leaning towards the Robin engine because I would hesitate to de-tune the Clements, and I would have to fab up a pull start for the Yamaha go kart engine. The Cuyuna is way too wide. Wouldn't mind coming across an HS50 or HS60 Tecumseh. I'm not modifying the frame, so I can put one in when it comes along. DSCN8659.JPG
 
M

msrfan

#52
#52
msrfan said:
I was correct mentioning my 8hp Briggs is too tall and so is the Kohler. But by removing the huge muffler, the Subaru Robin fits snugly, and the mounting holes line up. It has a 1'' PTO and I already have a nice #35 chain, 1'' clutch. If I go ahead with this engine, I'll gear it for 30-35mph tops. May have to add a wheelie bar. View attachment 250559 View attachment 250561
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I was wrong about the mounting holes lining up and that's why I had to make an adapter plate.
 
I74

I74

Well-Known Member
#53
#53
If I was building that bike & keeping it for myself, I would put that Clements engine on it & not even think twice about it.;)
Basically saying,, I would keep that engine.
I
 
M

msrfan

#54
#54
I74 said:
If I was building that bike & keeping it for myself, I would put that Clements engine on it & not even think twice about it.;)
Basically saying,, I would keep that engine.
I
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How would you set it up for starting the engine? I think building a totally custom bike around that engine would be the way to go. Also I don't have a carburetor or flywheel. I'm not totally rejecting the idea, just never dealt with these race engines.
 
M

msrfan

#56
#56
Roughed out the top engine mount and have it test fitted. Looks like it will work fine. Johnny Robles's Minibike/GoKarts is just a couple of miles from me and he has a 5" brake band that I may be able to make fit my 4 3/4'' clutch bell. He also has sprockets to fit the wheel I bought from him at the Long Beach Cycle Swap. Just have to catch him at home. Primary chain jack shaft sprocket selection is next. Brake lever and cable, throttle and grips should get it on the road. The engine came with an inline fuel valve and I have filters and hose. Oops, I forgot about foot pegs. Probably use some Harley buddy pegs I found at the swap meet because they need to be relocated away from the big motor and chain guard. DSCN8671.JPG DSCN8670.JPG DSCN8669.JPG
 
joshua. c.

joshua. c.

Well-Known Member
#57
#57
msrfan said:
How would you set it up for starting the engine? I think building a totally custom bike around that engine would be the way to go. Also I don't have a carburetor or flywheel. I'm not totally rejecting the idea, just never dealt with these race engines.
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if that engine is a briggs raptor parts should be easy to find, most small engine racing websites should have hop up parts for it. I would start by buying a billet flywheel for safety. and a briggs 5hp Flathead could be a good parts donor if you don't feel like hunting for every little peace. I've got a Roberts torque tubes header on mine and a 22mm mikuni and it runs quite well. as far as starting it just pull it over with the throttle shut and it wont kick. then just crack the throttle a bit once it fires. this is how I start mine and it sometimes takes a few tries but it works. I've never been hurt doing it this way. if I leave it out in the sun first and the engine gets worm it starts very easily.
 
M

msrfan

#60
#60
joshua. c. said:
if that engine is a briggs raptor parts should be easy to find, most small engine racing websites should have hop up parts for it. I would start by buying a billet flywheel for safety. and a briggs 5hp Flathead could be a good parts donor if you don't feel like hunting for every little peace. I've got a Roberts torque tubes header on mine and a 22mm mikuni and it runs quite well. as far as starting it just pull it over with the throttle shut and it wont kick. then just crack the throttle a bit once it fires. this is how I start mine and it sometimes takes a few tries but it works. I've never been hurt doing it this way. if I leave it out in the sun first and the engine gets worm it starts very easily.
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I have plenty of stock 5hp flathead Briggs parts. I can mount it on some boards and give it a test run.
 
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