Black Sheep Video
- Thread starter biknut
- Start date
It's funny, out of the box Black Sheep was slower than any motor bicycle I ever made. It barely would do 30 mph. Mopeds exist under special requirements in order to meet legal limits in most states. These Tomos mopeds are the last of the breed. After 59 years of constant production their performance now far exceeds most states legal definition of a moped. In order to keep them on the American market, the factory has to dummy them down quite a bit. All that's necessary to do 40 to 45 mph with the 49cc engine is to reverse engineer it back to full power and gearing. That's pretty easy to do.Nice ride.
More like keeping up with traffic *and passing.
Got any plans to hop it up?
The factory faces two problems staying legal. They have to comply with federal noise levels, and keep maximum speed under 30 mph. All they have to do to meet the noise requirements is put a big muffler with a catalytic converter on it, and choke the air cleaner side of the intake down. To keep the speed down they just make it do 30 when the rev limiter hits. Luckily they chose to change the gearing to accomplish that goal instead if moving the rev limit.
Just changing the rear sprocket from the stock 27T to a 22T ups the top speed to 35 mph with no other changes. Putting an expansion chamber and opening up the stock air box, with rejetting gets it to about 42 mph with my massive rump, but with a little weight reduction 45 mph easily attainable. Most of your typical moped riders don't need to lose weight to do it. I'm working on that part lol.
Another substantial performance gain I made was by tuning the clutches. This bike is a 2 speed automatic. It has 2 centrifugal clutches. They sell clutch springs with different strength than stock, that allows you to change the shift point. Stock it shifts very early in the powerband, probably to help pass noise tests. By delaying the shift point to higher rpm it not only accelerates faster in first gear, but when it shifts to second it's higher in the powerband so it accelerates better after the shift too.
That's where I'm at right now. I do have a big bore kit sitting on the shelf, but I'm not really in a hurry to install it, because it runs so well who cares. I'll get around to it one of these minutes though lol.
i see one here in my town for 20 bucks it definitely needs a new moter and possibly new tank and definetly a new tires anyways is that a good price for a old bike ?
the chains both are very rusty id say needing new chains as well . if its a good deal let me know ill buy the thing b4 they crush it
the chains both are very rusty id say needing new chains as well . if its a good deal let me know ill buy the thing b4 they crush it
