Clutch suggestion help

[Flatbar]

I have an electric scooter I'd like to convert to run on a 4.5hp Briggs. I need to have a centrifugal clutch, but, to complicate it, it needs to have a #25 pitch chain sprocket. (The dinky little electric scooter chain) All of the #25 clutches I have found so far are either roller clutches or for 49 cc 2 stroke pocket bikes. Any help is appreciated.


Flatbar


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[itsid]

well, no you don't you need a #35 pitch rear sprocket
(much easier to find, even in small sizes)

to tell how small...


'sid

 

[Flatbar]

The reason I'm Turing away from that option is because the rear wheel is quite tiny and I have to get a smaller sprocket to make it fit (4-5/8" OD) In that case, I would have no torque and way too much speed


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[thisismyusername]

The reason I'm Turing away from that option is because the rear wheel is quite tiny and I have to get a smaller sprocket to make it fit (4-5/8" OD) In that case, I would have no torque and way too much speed


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We need to know tire diameter, and what you want your ratio to be. Im not sure you will find a clutch for that pitch but you could probably easily just convert it to another type of sprocket like sid said. We have to see the tire setup before we can really suggest you anything to buy.

 

[Poboy kartman]

The reason I'm Turing away from that option is because the rear wheel is quite tiny and I have to get a smaller sprocket to make it fit (4-5/8" OD) In that case, I would have no torque and way too much speed


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Translation : With the limitations of the diameter of the rear sprocket limited by the small size of the rear wheel....when I go to a #35 sprocket...I lose so many teeth that my gear ratio is going to be fubar.....

 

[Flatbar]

Translation : With the limitations of the diameter of the rear sprocket limited by the small size of the rear wheel....when I go to a #35 sprocket...I lose so many teeth that my gear ratio is going to be fubar.....

Indeed.


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[itsid]

that's simply nonsense..

you need X*pitch to go around a shaft of a certain size,
it doesn't matter at all if
it's 19 teeth of #25
12 of #35
or 10 od #40

the circumference stays nearly the same
(nearly means it's not accurate but barely noteworthy!)

the gear ratio is easy to calculate with teeth, very true (and perfectly accurate as well)
but in fact it's about the diameter the chain wraps around

smaller pitch only means more teeth for the same circumference (thus diameter)!

so no matter how many teeth, the ratio will be off anyways.

Anyways.. 4 5/8 sprocket....
well 45 Teeth 219 chain (0.306 pitch; slightly larger than the 0.25 of the #25 chain)
(azusa)
clutch...
16T 219 4stroke clutch from heeters for example ($$$ yes, three figure pricetag!)
or maxtorque 16 Teeth 3/4 bore 219 chain (still expensive but a bit less)

That's the best ratio possible with a sprocket smaller than 4 5/8" and a PTO of 3/4".
(not good at all I guess )

Other than that.. Jackshaft!
#35 clutch & JS in, #25 JS out & sprocket; plus any gear ratio you want

'sid