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Hey!

What rear wheel are you running on your 45 (or...?)?
How is "acceleration" and "top speed" affected by using this wheel?

I'm starting to accumulate parts for my 45, and a big issue is determining what rear wheel to run.

I saw a guy (awhile ago) in an issue of the horse, and he was running a 6-speed trans with what looked like a honda or yamaha rear wheel (they have much smaller wheel sprockets than harley or triumph). I don't recall if he addressed the top speed he was able to get to or not; but I am guessing it was significantly faster than stock.

I don't believe that a 45 is "merely" capable of a top speed of 55 mph with all the knowledge and different interchangeable bits we have today, but maybe I'm just dreaming...?

But it'd be cooler if I wasn't and I could have some of ya point me in the right direction...
Thanks!!
 

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Generally speaking the 750 Flathead motor is not all that "slow" but the 3 speed gearbox hampers top speed, as does the cumbersome hand shift and wide ratios.

Generally speaking, gearing only makes you go faster if you have the motor to pull the gears. Gear it for 150 MPH (for example), but that does not mean that it will go 150 MPH without the motor to back it up.

The bigest gearing changes that you are going to make with a stock motor and stock trans are going to be done with the sprokets first, not so much with the rear wheel size.

You must always remember too that for every move you make toward more top end, generally speaking you lose some of the friendlieness of the lower end.

With all that said, use an 18 inch rear wheel.
 

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Assuming you are using the stock 45 transmission & rear brake/hub, the only thing you can really do is change the motor sprocket. Stock motor sprocket on a 45 solo is 30 teeth. You can get 'em as large as 34 teeth, but any 45 except a really hot, light job is gonna have trouble pulling a 34. Look around at the usual suppliers of 45 stuff & you'll find there are quite a few sizes available. As far as rear sprocket sizes go, I run an old metric rear brake/hub on mine & I was able to find several rear sprockets for it. That gives me even more combinations of ratios to play with. Also, if you use something common (which basically means metric...) you can get any sprocket size you want made for you.
 

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Oh, & to answer your original question, I run a 19" rear wheel. If yer gonna go with a 45 (H-D) wheel, I agree with Wes & I'd recommend an 18 also.
 

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anybody ever try the Paughco frame for 45's that uses a big twin 4 speed tranny? they even make an engine sprocket for the double row primary chain etc. I'd be interested to know how that works out for top speed among other things.
 

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anybody ever try the Paughco frame for 45's that uses a big twin 4 speed tranny? they even make an engine sprocket for the double row primary chain etc. I'd be interested to know how that works out for top speed among other things.
Exactly the same as a three speed , or even a one speed. Top speed is determined by the amount of power an engine can produce and a ratio of that power to weight. How it gets to the ground does not change the top speed, merely the time it takes to get there. So despite the tire size, the number of gear ratios, or the frame used, none of those factors change the amount of power produced. In fact Big Twin transmissions by their mass will reduce the amount of usable power from a 45 just from friction loss. So instead of looking for a magic wheel or fantasy transmission spend your effort on improving the efficiency of the engine and you will get real results. And any decent 45 will run 75 MPH with sustained 60-65. If yours will not it is sick. And not sick in a cool way!
Robbie
 

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Can you mount a old Brit pre-unit 4 speed tranny up to a 45? I own neither so honestly do not know.
 
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