Another dumb idea. 👍

[DieselTech]

The shifting thing was something I actually have.been trying to give some thought to. A Suicide shifter would be the easiest route to.go, but I wonder if I could make some kind of cable actuated thumb shifter. It would need.to be spring loaded so it returned to center after a shift.

You could make a thumb shifter fairly easy with a 12volt shift solenoid. Get a spring loaded to center dual polarity shift solenoid. Then it can push & pull the shift lever & its spring loaded to the centered posistion. Then just use 2 buttons on you handle bars 1 button for a upshift & 1 button for a down shift. Then just have your clutch on a normal hand clutch lever.

 

[ImpulseRocket]

You could make a thumb shifter fairly easy with a 12volt shift solenoid. Get a spring loaded to center dual polarity shift solenoid. Then it can push & pull the shift lever & its spring loaded to the centered posistion. Then just use 2 buttons on you handle bars 1 button for a upshift & 1 button for a down shift. Then just have your clutch on a normal hand clutch lever.

That's actually not a bad idea. The bike would have a charging system anyway and I could make a small 12 volt battery to hide under the seat easy enough.

 

[Sidewinder Jerry]

The shifting thing was something I actually have.been trying to give some thought to. A Suicide shifter would be the easiest route to.go, but I wonder if I could make some kind of cable actuated thumb shifter. It would need.to be spring loaded so it returned to center after a shift.

Nah, no need to shift all the time while riding. I don't want to actually go fast with it. 40mph top speed would be plenty. I would rather have the climbing power of the lower gears for the steep hills, and the high gear to keep the rpm down. I may be crazy, but 50+ on a bike isn't on my "need to do" list

I do want the pedals as well. I still want it to function as a bicycle if needed.

If you use 26" wheels at 7000 rpm you'll need a total reduction of 13.54\1 to do 40 mph. Which should be doable with over 8 hp.

 

[ImpulseRocket]

If you use 26" wheels at 7000 rpm you'll need a total reduction of 13.54\1 to do 40 mph. Which should be doable with over 8 hp.

The biggest challenge would honestly be gearing it down far enough. The smallest front sprocket available is a 13.

Of course, I guess it would also depend on what rpm I want to do whatever target speed at in what gear as well. If I set it to achieve 40mph at 7500rpm in 3rd gear, it could theoretically reach almost 60mph in 4th. If I try to make 4th the top speed gear, first would be almost useless unless I were going to the Himalayas.

This is why using a Phatmoto frame would be tempting, since they have the built in jackshaft, which is likely necessary in order to step the gearing down some to achieve a target rpm/speed, as well as proper chain alignment.

That being the least of all my problems to sort out anyway as I can't find any measurements of the engine anywhere to see if fitment is possible. I am sure it would be, but I like knowing with at least some certainty before I drop 500 bucks.

 

[ImpulseRocket]

The other limitation is rear sprocket size, at least if I want to use a rear disc brake, which I do. That would limit me to a 36 tooth out back. With a jackshaft I could run a second reduction ratio to try and achieve a final drive of around 4.10. That would give me a top speed in 4th gear at 8000rpm of 50mph, and in third gear of around 37mph. 30mph in third would be at 6500rpm, putting cruising speed right in the peak of the hp range. In 4th 35mph at 5600rpm, right at peak torque.

 

[ismellnownlatters]

Can bike tires even handle that kind of centrical force?

 

[ImpulseRocket]

Can bike tires even handle that kind of centrical force?

Must not read the posts of guys going 60mph very often lol

I regularly go 30 to 35 on my Phantom bike, and have hit 45 a couple times. You are missing the actual point. It isn't that I want to go 50. I stated my ideal speeds already, this is about finding a balance between speed and rpm in a given gear. My Phantom can go 50. Doesn't mean I actually go 50

 

[ismellnownlatters]

Wel have fun lolnu r a nice guy so be safe

 

[ImpulseRocket]

Wel have fun lolnu r a nice guy so be safe

The build is the most fun for me. Especially the planning and the math. I could endlessly build bikes and barely ride them and be quite content. My favorite part of my Phantom was tearing into the motor and building it how I wanted it.

 

[ImpulseRocket]

I did finally manage to find a dimensional drawing of the engine with some measurements. I have to change the format when I get home and I will post it, but here are some of the numbers on the size of it.

Front motor mount hole to rear motor mount hole is 11 inches (and change).

Total length from the edge of the sprocket cover to the front edge of the cylinder head is 15.35 inches, but that cover also sticks out a little bit more than the engine. The edge of the rear motor mount point is maybe an inch in from there. Half an inch at the least.

The bottom of the bottom mount point to the top of the head is 13.78 inches tall, but that lower mount also sticks out the bottom a solid inch or more than the bottom of the. Case itself.

Couldn't find any width numbers, but the engine is fairly square in dimensions, so width is likely around 14 to 15 inches at the widest points.