[royced720]

Hello All, My name is David, and I just joined moments ago. I am an experienced motorcycle rider, having toured in places like the alps, pacific coast, etc, as well as years of motocross, though at this time I don't ride street bikes. I;m a single parent who needs to stay in one piece, so for now my hobbies are things like mountain bikes, drumming, and cooking.

My son is 15, and we are working to build a custom e-bike together, in the style of a late-'60's hardtail chopper.
We want the machine to be able to ride two adults, which is pushing the limits of bicycle components, so we may use an older rebel 250 as a donor bike for components such as the front wheel, rear wheel, triple crowns, etc.

With that in mind, I need to figure out the drive ratios from the motor to the road (the plan is to make it single speed), meaning I need to know the outside diameter of the rear tire, to calculate what the speeds and torque will be at various motor speeds.

So I ask all of you experts:

What is the o.d. of a stock rebel 250 rear tire?

What sprocket sizes are available to bolt on to a stock 250 rim?

Also, if anyone is parting out a rebel, drop me a note. I don't think the frame would adapt well, so I plan to make my own frame (has to have functioning pedals to be defined as a bicycle), but I could likely use many other components as listed above.

thanks in advance. BTW I think it's really cool that you have a community for cyclists that may not have $25k or more to sink in to a big v-twin! My first street bike was a 440 two cylinder, and I had many great times touring around central Europe on it!

David

 

[Emil]

Welcome to The Forum !
My daughter is presently building an engine powered bicycle just less than 50 cc.
There are websites that explain the tire sizes external dimensions for motorcycles if you want to try those. Rebel uses a 15 inch rear tire, and many sprockets are available. Some go up in sizes, when using the engine, and some go down. I use a 30 tooth on my rear sprocket presently though the factory is, IIRC, 33T.
It sounds like a very interesting project. Keep us informed as to your progress. These things are always cool to learn about!

 

[flitecontrol]

Welcome to the forum. I have a bunch of first generation (1985-87 model years) 250 parts. Let me know what you need and I'll see what I have.

 

[Markrkolb]

Welcome! Best of luck with your project. The rebel is a great choice for your bike because there are a lot of them, and parts are cheap and plentiful.

 

[RebelHawk48]

What is the o.d. of a stock rebel 250 rear tire?

Hey, a question I can actually answer, having bought tires recently. The stock Rebel 250 rear tire is 130/90-15 with an outside diameter of 23.95 inches for the Dunlop D404.

Purchase Dunlop D404 Tires From Your Local Dealer | Dunlop Motorcycle

Need to replace your Dunlop D404 tire? Our dealer and PRO dealer locations have the inventory available to buy a new tire and get you back on the road. Check out our available rebates

www.dunlopmotorcycletires.com

Good luck with your build!

 

[wjmrty]

Welcome to forum n enjoy your interesting build

 

[royced720]

Welcome to the forum. I have a bunch of first generation (1985-87 model years) 250 parts. Let me know what you need and I'll see what I have.

hi- i'd be looking for: entire front end- wheel, tire, brake rotor with caliper, reservoir, brake lever assy, triple crowns and head tube bearings. Also- rear wheel with complete brake setup including lever, swing arm, rear axle, etc. I live in Michigan and may be scrounging the salvage yard this weekend. Let me know what you have. thanks.

 

[royced720]

Hi again all, thanks for the info on the rear tire. My spreadsheet says with that tire, the bike's max theoretical speed (no load) would be 34 mph when the motor was at peak torque shaft speed of 9k rpm. That's with a 1.9 final drive e.g. 38T cog up front and 20T on the rear. That might work OK since the load would likely bog it down to the max ebike speed of 28 mph. Actually more interested in hillclimbing torque than top end.

While I have you on the line- can anyone give me a primer on the rebel 250, such as did it go through any big design changes over the years? I see mention of Gen 1, Gen 2, etc. Will the parts mix and match, or are there showstopper differences? thanks

 

[royced720]

OK one more question for today- wanting to extend the front forks for the chopper style- if a commercial product isn't available, I'll need to make a set of extensions on a lathe- can you tell me the outside diameter of a stock rebel 250 front fork tube, and the thread used on the top cap?

Also, how is the oil added to the front suspension on a rebel 250?

Thanks

 

[Emil]

The biggest changes over the years were with the engine. That isn't going to be a problem for you.
Other than that, the side covers are metal on 1st gen and they're plastic on 2nd gen.
The front caliper and disc brake is on opposite sides for 1st and 2nd generations.
The wiring harness has a few different things, but again it's mostly for the electronics supporting the engine. You'll be doing almost all your own wiring, so no issues there.

As for filling the oil in the front tubes, the top cap is removed & the shock oil is poured in there. The 1st gen has a drain plug on the bottom as well as a reflector on the sides. The 2nd gen doesn't have these.

 

[royced720]

hi all, is there a rebel 250 maintenance manual online?