Clutch Why a Transmission ?

What is the purpose of a transmission on a 4 stroke Predator engine. Why can't I just put a clutch on the 3/4 shaft and leave it at that.
The fact that nobody does that might be a hint that there are very good reasons.

Everyone buys or makes a jackshaft aka "transmission"

Simple is a great thing!
As long as everything lines up, and you get the desired ratio you want, simple is great
You nailed the 2 reasons why a jackshaft or CVT is used.
 
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What is the purpose of a transmission on a 4 stroke Predator engine. Why can't I just put a clutch on the 3/4 shaft and leave it at that.
Now I see that you didn't mention in your question, "Looking into building a 4 stroke rear drive bike that has the proper brakes for safe stops"
A 212 cc mounted on the rack overhanging to the right so the chain lines up is one heavy cumbersome beast......
How much does a 212cc plus clutch weigh?

Be aware that cheap centrifugal clutches jerk and grab with a 212 cc.

I see you are in Socal so I am inviting you out to the Sat Oct 22nd race at Grange Motor Circuit in Apple Valley
Come on out to see the state of the art in motorized bicycles.
 
I would probably use the 3hp predator if I remember correctly it weighs 22lbs.
Who makes the best centrifugal clutches ? Apple valley sounds great. I will try and make it.
Thanks for your input, Manic Mechanic
 
Now I see that you didn't mention in your question, "Looking into building a 4 stroke rear drive bike that has the proper brakes for safe stops"
A 212 cc mounted on the rack overhanging to the right so the chain lines up is one heavy cumbersome beast......
How much does a 212cc plus clutch weigh?

Be aware that cheap centrifugal clutches jerk and grab with a 212 cc.

I see you are in Socal so I am inviting you out to the Sat Oct 22nd race at Grange Motor Circuit in Apple Valley
Come on out to see the state of the art in motorized bicycles.
Stopping was a major issue on my last bike. I was going to use a single front disc and rear hub on my next one. Still not sure if this is enough. Manic Mechanic
 
I would probably use the 3hp predator if I remember correctly it weighs 22lbs.
Who makes the best centrifugal clutches ? Apple valley sounds great. I will try and make it.
Thanks for your input, Manic Mechanic
You said 3/4" shaft so that is a 212cc. 79 cc has a 5/8" shaft. :)
Gearing ratio from the clutch to rear sprocket will require about a 100? tooth sprocket.

Why don't you put the 79cc motor centered in the frame? you will need a jackshaft plate, wider pedals, etc.

Look up Shane at AffordableGoKarts.com in Santa Barbara for clutches for a 79 cc.
 
You need a transmission because the powerband on an engine is fairly narrow. A transmission will allow you to keep the engine in it's powerband at different road speeds. My 225cc motorcycle will not go over 15 mph in first gear at full throttle, but it will go 70 mph + at full throttle in 5th gear.
 
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