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DIY Home Built Motorized Bicycle (non kit) Post all about your home built rides here. Weedwacker motors, lawn mower engines ect. This area is for non kit builds

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  #1  
Old 02-25-2016, 07:41 PM
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cannonball2 cannonball2 is offline
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Default Cannonball Builds a Briggs and Scrap Iron

Ive had this poor little 1976 3hp B&S for many years. It was headed for the scrap heap. I rescued it when I was in the small engine business as a parts source. I thought it was cute and tucked it away. Turns out only the points need cleaning. Its a reasonably uncommon configuration with the updraft carb, which is very compact, just perfect for stuffing into a bike.

I wound up with a Schwinn Delmar trade. The frame configuration is great. With a single top tube its wide open for bigger engines. The frame is also wide for larger tires/wheels.

So this is whats going on. This is really I guess a light motorcycle as the reduction will run through the bottom bracket. Ga does not require pedals so I guess I don't either. The drive will be to a Nexus 3speed IGH driven on the right side. I have been beating a Nexus with a 49cc 2stroke and it hasn't failed yet. I think with careful handling of the Briggs I can make it last if not I will find an SA IGH.

I'm really tickled about the way I did the bottom bracket. Normally I make discs to hold 5/8 bearings and weld them to the BB. What a PITA! This was a five minute bolt on and it clamps so well I couldn't budge it hitting the shaft with my copper hammer.

Will be running 26x2.4 Cyclops tires on 50mm rims. Has a new Cruzer(don't say Whizzer!) 8qt gas tank. One of the nicest tanks I seen from China.

This is where it is now. I'm in and out of town so it will progress slowly.
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  #2  
Old 02-25-2016, 09:17 PM
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Tony01 Tony01 is offline
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Default Re: Cannonball Builds a Briggs and Scrap Iron

Oh man that BB.. why didn't I think of that..... so good!

which 50mm rims do you plan on running?
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  #3  
Old 02-25-2016, 11:51 PM
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cannonball2 cannonball2 is offline
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Default Re: Cannonball Builds a Briggs and Scrap Iron

My wife gets bikes from the thrift stores in our area for me to use as donors. These were from a Huffy Regatta, complete with the Nexus hub.
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Old 02-26-2016, 06:16 AM
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Default Re: Cannonball Builds a Briggs and Scrap Iron

Yeah!!!following...bb..its nice how some ideas just come together eh..i like those Cyclops..i got 1600 miles on mine. Like the tension set up too.
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Old 02-26-2016, 08:19 AM
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cannonball2 cannonball2 is offline
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Default Re: Cannonball Builds a Briggs and Scrap Iron

Thanks!

I have been running Hookworms and they are great tires. The Cyclops seem to be comparable but cost much less. I have been running Cheng Shinn tires for years on M/Cs.

Ive had good results running the hard skate wheels as idlers. You get 4 for $10 with really nice bearings. I prefer spring loaded idlers but there was no practical way to use a spring in this set up.

This Briggs had one of the blocks that had the cast in air guide in the front. A bit of work with a hacksaw and Dremel liberated the cylinder for more of an engine look will probably aid in cooling while moving. The guide was very necessary when the engine was used in a stationary mode. I also rounded the head to match.
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Old 02-26-2016, 09:18 AM
curtisfox curtisfox is offline
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Default Re: Cannonball Builds a Briggs and Scrap Iron

WOW! got to watch this,KOOL bottom bracket mount shaft, never cease to amaze me with your ingenuity......................Curt
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  #7  
Old 02-26-2016, 11:53 AM
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Default Re: Cannonball Builds a Briggs and Scrap Iron

Oh, yeah I was wondering about the 'look' of the engine. I was looking how to remove the same on mine, ended up just drillin holes. I got one to practice on. What you did is a nice look. Skate wheels��
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Old 02-26-2016, 01:06 PM
curtisfox curtisfox is offline
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Default Re: Cannonball Builds a Briggs and Scrap Iron

CB 2 what size is the shaft 3/4" ?...................Curt
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  #9  
Old 02-26-2016, 03:47 PM
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cannonball2 cannonball2 is offline
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Default Re: Cannonball Builds a Briggs and Scrap Iron

Curt the shaft is a 5/8. A 3/4 could be used if the bearing housings are not excessively large.
These are close flange bearings. They have the holes as close to the bearings as possible. When bolted down the bolts are against the BB tube locking the bearings positively in place.

Got the drive line finished. The largest sprocket I could fit with out frame interference was a 44t. To get the ratios I had to resort to a 9t front. Not a lot of teeth! There are 5 in the chain at all times so should be fine as long as the chain remains tight.

I like to run BMX chains they are smaller, plenty tough and fit the common CG sprockets.
better. Problem is most driving sprockets don't fit. I thinned this sprocket(it was for a #40 chain). I locked it to a piece of jackshaft and put a bearing on the shaft. By holding the bearing and evenly spinning the sprocket against the wheel on my grinder I had a custom machined sprocket in about 15min. I faced it by turning it against a 60 grit sanding disc with my drill press. Home machining at its best!

I will be running BMX rim brakes. The best fit is right behind the motor. Will make a mount that fits off the motor mount. This ones going pretty well/fast.
but the devil is in the details as usual.
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  #10  
Old 02-26-2016, 06:25 PM
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Default Re: Cannonball Builds a Briggs and Scrap Iron

Your engine looks like mine did in the beginning!! I like your creative thinking. If its layin around...its like umm if I do this, I can use that. Hey I've read some of your elec. build threads, and was wondering if you know how useful are unite motors. I clean a guys shed out was there was a 500w razor, so I thinking of using it, on my cargo bike. Dang you already got your tires! Gonna be a mover!!
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