does anything like this exist?

Toby woodman

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Mar 4, 2023
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having built mutliple 2 and 4 stroke bikes, including china doll motors, and custom jackshaft 4 strokes using a honda gx160, im wondering if there is any product, or parts that could be used to acheive this build. I don't want my bike to go more than about 35 mph, any faster and its sketchy, and too low torque for steep hils where I am. My bike built with the big honda was powerful but all but the best custom motorized bike wheels would break under the strain, and the centrifugal clutch was a nightmare. it had plenty of power but it kept breaking parts. What I really need is a 49 to 80cc 4 stroke engine, with a manual clutch and a single gear ratio, much like the 2 stroke engines, the 49cc would be economical and super reliable, and would be powerful enough to keep up with a china doll 2 stroke with the muffler cap removed while also being kind to budget wheels and easy on the rest of the bike. The manual clutch would make the bike much easier to ride, and remove the constant worries from a go kart centrifugal clutch. it would also be compact. again, I think that 35mph is plenty, at least where I live, Ideally it would be more like 28 miles per hour. if you need to go faster or futher, a motorized bike in my opinion requires too much money and work to be as dependable as for example, a 125cc moped would be. Im just wondering how to put this sort of dream bike together. Any ideas? another great thing about the four stroke's are that they deal with hot weather and slower riding better since they don't require fast speeds to cool the motor.
 
here are some past bikes
 

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@Sidewinder Jerry

I have an overkill build using a 224 and Series 30 torque converter/CVT

If I remember correctly, Reduction is between 4:1 and 1:1 depending on load.

There is also a bigger torque converter driven wheel that is much higher reduction if torque is what you're after.

These use standard length straight shafts (something like 2.3" long) typically 3/4” diameter, but you can adapt a 5/8”

As far as manually clutched, there are kits for minibike/go-karts, but expect to spend $350 or more.

Sidewinder knows a lot about gear reduction and smaller engines, but I believe he uses a centrifugal clutch.

Centrifugal clutches work fine if they are geared correctly.
 
here are some past bikes
My latest concept for small 4 strokes 49/53 is a 3\1 CVT 10t ran to a jackshat 30t | 10t behind the seat then ran to the rear wheel 60t. This way the reduction range could be 54\1 to 18\1. Giving you hill climbing abilities without compromising top level ground speed. Along with keeping everything classified as an automatic transmission system satisfying legal requirements in many places.
 
legal is not a problem for me because I'm in the uk, I'm only 16 so im doing pretty much all of this illegally, however, i live in the countryside and have ridden probally over a 1000 miles now with no problems. how do the cvt's do with smaller engine's and an adapted shaft, for instance a 79cc lifan and a jackshaft, do they rob too much power from resistance for the smaller engines
 
My main issue is space, here in the uk, there are pretty much no large beach curiser bikes, i am restricted to usually smaller steel 90's mountain bikes, which is why the 49cc would be so desirable. as you can see, my gx160 bike was pretty unruly and fairly sketchy
 
My main issue is space, here in the uk, there are pretty much no large beach curiser bikes, i am restricted to usually smaller steel 90's mountain bikes, which is why the 49cc would be so desirable. as you can see, my gx160 bike was pretty unruly and fairly sketchy
There is a lifan 156F slant engine that is pretty small, basically a 1ft cube.

Only 3.5hp so it's not going to be a dragster, but the CC's will help it pull.

Seeing you have some fab skills you could get a 50cc Honda clone to work with a cvt+jackshaft setup like sidewinder said... but it's going to take a lot of work.
 
having built mutliple 2 and 4 stroke bikes, including china doll motors, and custom jackshaft 4 strokes using a honda gx160, im wondering if there is any product, or parts that could be used to acheive this build. I don't want my bike to go more than about 35 mph, any faster and its sketchy, and too low torque for steep hils where I am. My bike built with the big honda was powerful but all but the best custom motorized bike wheels would break under the strain, and the centrifugal clutch was a nightmare. it had plenty of power but it kept breaking parts. What I really need is a 49 to 80cc 4 stroke engine, with a manual clutch and a single gear ratio, much like the 2 stroke engines, the 49cc would be economical and super reliable, and would be powerful enough to keep up with a china doll 2 stroke with the muffler cap removed while also being kind to budget wheels and easy on the rest of the bike. The manual clutch would make the bike much easier to ride, and remove the constant worries from a go kart centrifugal clutch. it would also be compact. again, I think that 35mph is plenty, at least where I live, Ideally it would be more like 28 miles per hour. if you need to go faster or futher, a motorized bike in my opinion requires too much money and work to be as dependable as for example, a 125cc moped would be. Im just wondering how to put this sort of dream bike together. Any ideas? another great thing about the four stroke's are that they deal with hot weather and slower riding better since they don't require fast speeds to cool the motor.
Mine does 41 mile an hour and it's still uses the stock clutch just black clutch pads+ 5 green ones mixed in, but your best bet is going to be to buy you a set of aluminum mag rims they have a six hole sprocket mount that also doubles as a disc break mount, you won't be breaking any spokes
Also would recommend that you run a 36-42 tooth sprocket if you're looking to cruise around on a stock kit and still be able to run around 30 mph and save your engine from the high RPMS and kill your kit, while also keeping your torque
 

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