Engine

An engine for this bike had to be something out of the ordinary. Original Harley and Indian motors were not within the budget. I plan to have this bike finished for what a basket case motor would probably sell for. But also having a common everyday motor in the frame wasn't the goal. I decided to find a motor that's not really known in the Car Show/Cycle crowd. One that would not be easily recognized and would have people scratching their heads. So the hunt began, the motor I wanted for this bike had to have the following:
>Vertical Single Cylinder
>Overhead valves
>4 stroke
>at least 350cc,
>able to mate up to a separate transmission
>Horizontal crankshaft
>Simple mounting points.
>Available Service parts
>Correct crank rotation
>Charging system that could handle lights
>Look like nothing else.

       I searched though hundreds of different engines, Farm engines, Industrial engines, Stationary engines, Hit or Miss engines,Lawn Mower engines, and on and on. Not finding anything that fit the bill. I did however start to look more and more at Overhead Valve industrial engines. These are used in many applications and are made by the likes of Tecumseh, Briggs & Stratton and Kohler.

      I found a 16 hp Tecumseh OH160 ohv engine on ebay, which I was the high bidder. And it was 45 minutes away from me. The specs looked good:
Cast iron block
OHV
16 hp 500cc single
20amp charging system
1'' crank shaft with keyway
4 bolt bottom mounting
And Electric Start!

These are the actual picture from the ebay auction

  

Build Log

I studied frames from the 20's and early 30's to get as close the the correct dimensions as possible. I soon realized that using the Yamaha frame would bring a few compromises. The neck angle and the bottom lower horizontal rails were set from the factory, I had to work with this to get as close to the look I wanted. After establishing the wheelbase I began to draw out the frame. These were my dimensions:

  I made 2 mounting locations for my frame table to hold the frame. Each were T-style vertical box tubing clamped to the table at each end,. One would anchor the rear axle plates and the other would be the Neck Jig.

These were the stock Yamaha axle plates, just covered with body filler.

Using a 4'' Grinding wheel I removed the plastic filler and
cut off the pipe from the previous owners hardtail.    

These still needed cleaning up but I decided they were worth re-using

Rear plates mocked up in frame jig holder

Another view

The neck half of the frame jig presented a challenge. The last thing I need in a small 1-car garage is a large welded frame jig taking up space. So I used the same type of tubular steel 'T" frame for the neck, welded a pivoting threaded rod and began making the Neck half. I used the drill press to turn wooden half moons to fit the neck bearing cups. Then I drilled through the center for the threaded rod to pass through, large washers were added on top and bottom and it was capped off with a nut.

Lower pivoting area, frame neck is on left top, jig half is on right.  

Getting a view of the frame, I used this pic to sketch
some rough mock-ups. See below.

18'' wheels and an Indian type Leaf Front End. See the compromise in the front down tubes.
They run at a different angle and get horizontal too soon.

The jig was holding the frame well. time to set the wheelbase and height.

I had the engine and trans mocked up earlier, you can see my notes on the table top

 Lower rear legs were bent and slugged.

The inside width between the rear axle plate was narrower than the lower front down tubes. You can see how the tubes had to be brought inwards to arrive the correct point.

Engine mocked in place, note silver conduit used
for test bend of lower legs.

Checking rocker cover clearance with frame top backbone

18'' Rear wheel from Honda CB200T

Ford Model A spare tire cover with stainless moulding.

Front Wheel  form Honda CM200T, Rotor disc removed.

BSA A10 4-speed transmission test fit-up.

Center seat post set in position, this post has a 15 deg bend midway down

Donor Bike

Originally I was drawn towards Old Board Track Race type bike when I came across builders using common bicycle frames and adding a small 2 stroke motor with a 2nd set of chain and sprockets. I was hooked with the beauty and simplicity of these replica bikes but was disappointed in the fact that they could not be ridden legally on public roads. The idea of taking my board track racer by trailer to shows and events was not at all appealing. So I began a list of certain 'Must Have' items for this bike.
-Clear title
-Enough engine power to keep up safely in traffic.
-18'' wheels
-drum brakes
-Separate Transmission, not a 'Unit' type motor
-Hardtail frame
-12v Electrical System for Lights etc.

   Plan A: I began sweeping the web for something to start with, Not sure at first what I needed I looked at the smaller 2 stroke Harley/Indians from the 60's and 70's, problem was none of them ever had paperwork to go with the bike. That was tough because I really liked the idea of the paperwork on the completed bike to read "Indian or HD", oh well.
    Plan B: Find an inexpensive Japanese bike with a good title to start with, make it a hardtail and go from there.  Well, After sweeping Craigslist for weeks I came upon this, A 1981 Yamaha XS400 unfinished project bike for sale with a title. And under an hour away from where I live.

I got the bike back home and stripped it down to the bare frame. The back half of the frame had been hard tailed and was cut back to the original Yamaha tubing. I jigged up a worktable to lay out the frame to set the wheelbase and neck angle I wanted.

Steel work table from scrap yard with plywood base, top will get sheet aluminum cover.

Since I would be welding on this table I added a pair of flip down casters on one end. I could now roll the table out into the driveway and weld the frame without sparks in the garage.

Casters in up position

Casters in Down Position

Inspiration

The bike I'm building is inspired by the 1920's single cylinder motorcycles. Namely the Harley peashooter 350/500 and Indian singles. The mid to late twenties is interesting to me because it was a time when motorcycle design abandoned their bicycle look of thin tires and frames and became much more robust.  

The Beginning....

Welcome,
I'm starting this blog to share the build of a vintage tribute motorcycle and to exchange ideas with others with the same interests. I'll be documenting the build process and posting pictures and descriptions as things progress. Enjoy! -Vince