Ok, so I've gotten a fair amount of positive feedback from the guys when I bring this puppy along to an event.
I certainly get a lot of appreciation shown and enjoyment demonstrated at Bakersfield when Josiah Rogers shows up.
He is a bit of a "favorite" of mine ever since I was able to outfit him with loaner gear at Prairie City some years ago when he was offered a ride in a single 820, but showed up in shorts - at which point grandpa Dan said, "See, I told you to wear long pants. Too bad you can't take a ride..." At which point I motioned Jo to visit me in my trailer, and in a few minutes he was fully outfitted with a black driving suit, black gloves, black head sock, black helmet and black neck brace. The "man in black" was ready to hit the track - and took his balaclava home as a souvenir.
Since then I have offered Jo first dibs on the mini bike, which he apparently enjoys immensely.
Part of what vintage karting is all about is sucking in the young 'uns.....
So now on to the build story of the mini bike.
A little bit of background first, though.
The mini bike was actually put together as a gift for a dear friend of mine, Mike Kearns, who worked for me for 10 years, and was possibly the best employee I ever had. He came to me as a "retreaded" carpenter who had torn up his rotator cuff and went back to school to learn CAD drafting. Combined with his experience being a framer, a steam locomotive nut and a Harley Davidson afficianado, he had the perfect background to be an MEP (mechanical, electrical, and plumbing) designer/draftsman. He did well at this, and created a whole new career for himself, which served him well as his final career.
So, one day he mentioned that he thought it would be cool to have a "Doodle Bug", which was an early verssion of a mini bike.
So, a few days before Christmas 2010 (as I recall), a box showed up on his front stoop. He opened it and found a Bad Dog mini bike kit inside. His next action was to call me and advise that I had mistakenly had an item of mine delivered to the wrong address - which notion I quickly squashed, explaining that it was not a mistake, and that I had an engine, gas tank, etc., that was all that was needed to complete the kit, and that we would finish the project together, once he assembled the roller that was in pieces on his porch.
Would it be that life would be so easy......
When we got together to finish the project we discovered that the mechanical caliper brake arrangement (using the sprocket as the disc) had the caliper mounted so high (obviously intended for an upright 4-cycle engine) that the chain arrangement for the NOS US Motors 580 was completely unworkable.
Some substantial work was needed, and time lapsed, and finally Mike gave up and re-gifted the the mini bike to me and abandoned the project. I reluctantly accepted it back - but of course I was determined to finish it, and give it to him anyway - he just didn't know that.
As you will see, there were four basic modifications that needed to make this mini work, as follows:
1. The gas tank needed a proper mounting.
2. The 580 engine needed a "high-rise", angle mount to allow the chain to miss an original factory style exhaust.
3. Further, a jackshaft was also needed to keep the chain from interfering with the exhaust - and the jackshaft needed to be adjustable because the rear axle was mounted behind the frame in a fixed position and could not be adjusted for chain tension.
4. An Azusa combination drum brake and sprocket assembly was needed - but it had to be specially adapted to the modern one-piece spun aluminum rear wheel and modern axle with 3-bolt with bearing hub. This part of the project was actually unnecessary as changing to an Azusa Tri-Star rear wheel would allow the combo sprocket/drum to bolt directly to the Tri-Stsr wheel, but that would spoil the modern spun wheel look. I admit to being hard headed in this regard. While it was unnecessary, it did end up being a pretty cool solution to the problem of mounting a sprocket/drum unit to a modern spun wheel and hub assembly.
The photo below shows the "roller" mini bike as sold by Bad Dog.....
I certainly get a lot of appreciation shown and enjoyment demonstrated at Bakersfield when Josiah Rogers shows up.
He is a bit of a "favorite" of mine ever since I was able to outfit him with loaner gear at Prairie City some years ago when he was offered a ride in a single 820, but showed up in shorts - at which point grandpa Dan said, "See, I told you to wear long pants. Too bad you can't take a ride..." At which point I motioned Jo to visit me in my trailer, and in a few minutes he was fully outfitted with a black driving suit, black gloves, black head sock, black helmet and black neck brace. The "man in black" was ready to hit the track - and took his balaclava home as a souvenir.
Since then I have offered Jo first dibs on the mini bike, which he apparently enjoys immensely.
Part of what vintage karting is all about is sucking in the young 'uns.....
So now on to the build story of the mini bike.
A little bit of background first, though.
The mini bike was actually put together as a gift for a dear friend of mine, Mike Kearns, who worked for me for 10 years, and was possibly the best employee I ever had. He came to me as a "retreaded" carpenter who had torn up his rotator cuff and went back to school to learn CAD drafting. Combined with his experience being a framer, a steam locomotive nut and a Harley Davidson afficianado, he had the perfect background to be an MEP (mechanical, electrical, and plumbing) designer/draftsman. He did well at this, and created a whole new career for himself, which served him well as his final career.
So, one day he mentioned that he thought it would be cool to have a "Doodle Bug", which was an early verssion of a mini bike.
So, a few days before Christmas 2010 (as I recall), a box showed up on his front stoop. He opened it and found a Bad Dog mini bike kit inside. His next action was to call me and advise that I had mistakenly had an item of mine delivered to the wrong address - which notion I quickly squashed, explaining that it was not a mistake, and that I had an engine, gas tank, etc., that was all that was needed to complete the kit, and that we would finish the project together, once he assembled the roller that was in pieces on his porch.
Would it be that life would be so easy......
When we got together to finish the project we discovered that the mechanical caliper brake arrangement (using the sprocket as the disc) had the caliper mounted so high (obviously intended for an upright 4-cycle engine) that the chain arrangement for the NOS US Motors 580 was completely unworkable.
Some substantial work was needed, and time lapsed, and finally Mike gave up and re-gifted the the mini bike to me and abandoned the project. I reluctantly accepted it back - but of course I was determined to finish it, and give it to him anyway - he just didn't know that.
As you will see, there were four basic modifications that needed to make this mini work, as follows:
1. The gas tank needed a proper mounting.
2. The 580 engine needed a "high-rise", angle mount to allow the chain to miss an original factory style exhaust.
3. Further, a jackshaft was also needed to keep the chain from interfering with the exhaust - and the jackshaft needed to be adjustable because the rear axle was mounted behind the frame in a fixed position and could not be adjusted for chain tension.
4. An Azusa combination drum brake and sprocket assembly was needed - but it had to be specially adapted to the modern one-piece spun aluminum rear wheel and modern axle with 3-bolt with bearing hub. This part of the project was actually unnecessary as changing to an Azusa Tri-Star rear wheel would allow the combo sprocket/drum to bolt directly to the Tri-Stsr wheel, but that would spoil the modern spun wheel look. I admit to being hard headed in this regard. While it was unnecessary, it did end up being a pretty cool solution to the problem of mounting a sprocket/drum unit to a modern spun wheel and hub assembly.
The photo below shows the "roller" mini bike as sold by Bad Dog.....
Jim Waltz, West Sacramento, CA
