1913 BSA copy

[Goldy]

There doesn't seem to be much activity on this forum, so I thought I would start a build thread on my latest project. What I intend to produce is something that resembles the 1913 BSA motorcycle in the attached photo. Depending on how busy things are in the shop this winter, I can't hazard a guess as to how long it is going to take, but I will attempt to post updates as things progress. The second photo is of the bicycle I started with...a 1980s Supercycle that was picked up along with it's sister bicycle for a whole $30.00. Next shot shows the seat post lowered about three inches and the rear frame struts lowered and shortened to fit. After that a replacement crossbar (4" extension) and brace were fabricated and welded in place. The front downtube was then curved to follow the curve of the wheel...plenty of room to fit the engine and primary drive, while still being able to retain the cranks (keeping them on the bike will help me stay under the radar of the local constabulary). Going to stick to chain drive with a centrifugal clutch as with the cyclone bike, 5HP B&S engine will provide the motivational force. I'm going to try to sort out a way modify the clutch to enable a pedal start.

 

[corgi1]

that looks good........................

 

[Goldy]

Did a bit more tinkering, got the bottom engine cradle and mounts fabricated and welded in place today. Engine looks grubby from sitting in the garden shed for years, but is mechanically sound...will get the 'royal treatment' later on.

 

[kipharley]

Hi,Goldy.That is going to be an interesting build,keep the pics coming!What's that yellow honey in the back-ground in the second pic?and what year is that Norton? can't wait to follow your build!Always loved British bikes!Thanks for posting it! Kip.
[email protected]

 

[Goldy]

Hi,Goldy.That is going to be an interesting build,keep the pics coming!What's that yellow honey in the back-ground in the second pic?and what year is that Norton? can't wait to follow your build!Always loved British bikes!Thanks for posting it! Kip.
[email protected]

Thanks! That yellow honey is a cyclone board track replica I did over the past year. The Norton is a 1948 model ES2

 

[Bike Monster]

its looking good cant wait to see the finished product!!!!

 

[msrfan]

Awesome idea. 5hp Briggs is my favorite motorbike engine choice. You may be able to use a clutch bearing (sprag or one-way bearing) on the centrifugal clutch. It will freewheel backwards and turn the motor over with any forward movement. May need a compression release to help starts. I can help you with that.

 

[discontinuuity]

Awesome idea. 5hp Briggs is my favorite motorbike engine choice. You may be able to use a clutch bearing (sprag or one-way bearing) on the centrifugal clutch. It will freewheel backwards and turn the motor over with any forward movement. May need a compression release to help starts. I can help you with that.

Could you elaborate on that? My 3hp B&S has a sprag clutch for the rope start mechanism, and a go-kart style centrifugal clutch on the output side of the engine. Are you saying that there's a way to bump-start an engine with a centrifugal clutch?

 

[msrfan]

Could you elaborate on that? My 3hp B&S has a sprag clutch for the rope start mechanism, and a go-kart style centrifugal clutch on the output side of the engine. Are you saying that there's a way to bump-start an engine with a centrifugal clutch?

There may be a way to install a sprag bearing in your existing clutch if there's room. It would have to replace the bearing or bushing that the drum rotates on. I don't know what kind of cent. clutch you have but a little modification to make it pedal start may be possible. You need to get with your local bearing outlet to find what sizes are available. Are you're going to make yours belt or chain drive?

 

[Goldy]

Could you elaborate on that? My 3hp B&S has a sprag clutch for the rope start mechanism, and a go-kart style centrifugal clutch on the output side of the engine. Are you saying that there's a way to bump-start an engine with a centrifugal clutch?

I've got a rough design for a centrifugally released set of starter pawls. It will require some slight machining and modification of the clutch I am going to use, but should work without increasing the overall width of the clutch by more than 1/8". When it's tried and tested I will post the details.

 

[Goldy]

Took a bit of time off to build a primary reduction jack shaft today. I was going to use heavier bearings/ shaft combination, but I got to thinking the pedal crank shaft is made out of forged steel and the bearings are just like new, it ought to be more than strong enough to hold the primary reduction in place...this is what I came up with; engine will drive the large sprocket through a centrifugal clutch , the smaller sprocket will drive the secondary sprocket on the rear wheel. The hub that the sprockets are welded to was machined to hold the two sprockets on centre prior to welding them in place and the sprocket hub was machined to fit the crank shaft and bolted on using the left side crank retaining nut. The whole affair seems pretty robust and runs within 0.002" of true...that's good enough for the girls I go out with.

 

[Goldy]

Got some spare time to do a little more work on the bike today. Fitted the engine, trimmed the mounts. After removing the bearings and axle from the rear wheel, turned a flange to fit the hub and after welding it in place and checking for run-out, fitted the rear sprocket. The rear sprocket is a left over from the Cyclone build, runs perfectly true radially and within 0.003" axially. Removed the extra sprockets from the right side, greased up everything and slapped it back together. Next step will probably be to relocate the pedals.

 

[Bike Monster]

looking good!

 

[curtisfox]

AWESOME! love the Briggs builds. Keep the pictures comeing.

 

[Gbrebes]

Hey Goldy,

I am very interested in this build. I am using a briggs and stratton motor in my motorized bicycle project and I am also basing my build on a very similar vintage motorcycle (1914 Triumph in my case).

I have a couple of questions. Are you going to be having bike pedals on this motored bike? Also what kind of chain are you using on the drive side? The engine that I got came with a centrifugal clutch, so I would like to use it with a chain drive, I am just not that familiar with the mechanics of this part of the build.

Any specific information would be greatly appreciated. I am very impressed with the drive line of your bike so far.

Gilbert

 

[Goldy]

Hey Goldy,

I am very interested in this build. I am using a briggs and stratton motor in my motorized bicycle project and I am also basing my build on a very similar vintage motorcycle (1914 Triumph in my case).

I have a couple of questions. Are you going to be having bike pedals on this motored bike? Also what kind of chain are you using on the drive side? The engine that I got came with a centrifugal clutch, so I would like to use it with a chain drive, I am just not that familiar with the mechanics of this part of the build.

Any specific information would be greatly appreciated. I am very impressed with the drive line of your bike so far.

Gilbert

Where do I start....yes I'm going to keep the pedals, was working on them yesterday, will post photos when I have them relocated. I'm using a #40 chain and sprockets on the drive side. You may have already looked, but I suggest you have a peek at a couple of my other posts for inspiration..."cyclone replibike" and "wanna be". The Truimph is a beautifull old machine too, I wish you the best of luck!
Thanks for the inspirational comments guys!

 

[Goldy]

Here's what I have come up with for pedal gear...machined out a new crank axle, wider to clear the primary reduction sprocket...shortened the cranks by 2" and made up a new carrier tube to hold the whole thing...oilite bushings to support the shaft and the whole set up will be welded under the frame just behind the primary reduction spindle. When I get it welded in and the chain in place will post another shot.

 

[Goldy]

Here we go...pedal bushing carrier welded in place and pedals on...all I need to complete this part of the job is a simple little clamp-on chain adjuster.

 

[curtisfox]

Got some spare time to do a little more work on the bike today. Fitted the engine, trimmed the mounts. After removing the bearings and axle from the rear wheel, turned a flange to fit the hub and after welding it in place and checking for run-out, fitted the rear sprocket. The rear sprocket is a left over from the Cyclone build, runs perfectly true radially and within 0.003" axially. Removed the extra sprockets from the right side, greased up everything and slapped it back together. Next step will probably be to relocate the pedals.

OK what you did is turned the sproket out to fit the hub and welded it to the rear hub? On the outside next to the spokes? Thats KOOOOL If thats so I did that 50 years ago only used the big crank pedal sproket, and the small sproket off the rear wheel on the jackshaft.
You have one of the finest builds going love it ...Curt

 

[curtisfox]

Did a bit more tinkering, got the bottom engine cradle and mounts fabricated and welded in place today. Engine looks grubby from sitting in the garden shed for years, but is mechanically sound...will get the 'royal treatment' later on.

What is the bottom motor mount tube off from it fits so good.