No clutch??

[mat93]

hey i was wondering if it was possible to make a mini bike without a clutch? if so how can you do it

 

[Russ2251]

Known as direct drive. Instead of securing this to pto:

One of these would be used instead:

Attached to pto with set screws and key.
I use them for testing purposes.
They are available in various shaft sizes, chain size, and amount of teeth.

 

[modelengineer]

In a mini bike direct drive is less of a problem than in a kart, since you can easily push the mini bike. However, it is annoying to have to stop the engine to stop the bike.

If you are trying to save money, increase reliability and decrease maintenance it is good, but keep in mind it could annoy you more than you think.

 

[Russ2251]

Some direct drive sprockets here

 

[Cotmullion]

It is certainly possible and does work, as my minibike is clutchless, but it will have to be push start.

 

[mat93]

thanks for that but im using a lawnmower engine. I have already made it a horizantal shaft, but it has a thread and i was wondering if there was a sprocket out there that screwed on. otherwise i might just a weld a sprocket onto the front.would this idea work? thanks guys

 

[Russ2251]

Welding can be done but could destroy temper of steel. Breakage is a real possibility especially if load is on very end of pto.
What engine are you using?

 

[mat93]

i am using a victa G4. It is an australian brand and is two stroke.

 

[Russ2251]

Aha!!! Another global warming survivor. I envy you.
160 cc's?
Have you checked diameter of shaft with caliper? If so, what is dimension?
If you look around this site, you will find that I've posted extensively on converting Lawn-Boy vertical shaft 2 cycles to run in horizontal position. Lawn-Boy's are the US equivalent of Victa.
Check this out:
http://www.diygokarts.com/vb/showthread.php?t=140
And this:
http://www.youtube.com/watch?v=Rse7txNiKoE

 

[mcbob]

Have a look at my web site and it has details on the adaptor you need to run on your Victa 125 or 160cc engine i use a Max Torque type of clutch with a 3/4" ID and the clutch fits perfectly as this was the required clutch for the Delteks and Deckson mini bikes in Australia.

http://www.users.bigpond.com/ozflea/vintage_bike1.html

Mc Bob.

 

[mat93]

thanks

hey thats great!!
i was wondering if this idea affects the hp negativly? if so what can i do?thanks again for the links.
p.s how much hp does the victa G4 have? i cant find it anywhere

 

[mcbob]

Instead of cutting grass the old Victa turns out to be a good mini bike engine and will do it's job for many years to come.

HP wise it's got torque exactly what the mini bike needs.

Mc Bob.

 

[mat93]

how do u make the throttle. im having trouble. does no clutch affect the engine negativly??

 

[mcbob]

Well i don't quite understand your responce a centrifical clutch expands as revs increase allowing a little slippage till the mini gets moving bit like driving an automatic car.

Bob.

 

[Cotmullion]

Known as direct drive. Instead of securing this to pto:

One of these would be used instead:

Attached to pto with set screws and key.
I use them for testing purposes.
They are available in various shaft sizes, chain size, and amount of teeth.

Where do you buy those keyed sprockets? What size chains are they for? How many teeth and whats the shaft bore and woodruff size?

 

[Russ2251]

Where do you buy those keyed sprockets? What size chains are they for? How many teeth and whats the shaft bore and woodruff size?

Click link in post #4 this thread.
These use straight keys in sizes posted in link, not woodruff.

 

[mcbob]

The clutch on the Victa's is a tapered shaft that requires no key it's an interferance fit that snugs up tight on the taper then as the outer sleeve is tightened it retains the clutch simple and effective.

There no negativty here just simple engineering these engines run at between 3600 rpm and with the correct amal carby will run higher mine run around the 4500 rpm.

These are a far better engine than the Lawnboy will ever be.

Mc Bob.

 

[Russ2251]

These are a far better engine than the Lawnboy will ever be.

This is exactly the kind of statement I would expect to hear from someone with a complete paucity of experience.

 

[modelengineer]

Arguably the best mower engine is this one:
http://www.cairnsmowercity.com/prod175.htm
Now, if I could only steal my Dad's one while he isn't looking... hehe, unlikely.

 

[Russ2251]

...these engines run at between 3600 rpm and with the correct amal carby will run higher mine run around the 4500 rpm.

4500 RPM? If that were true of L-B, I wouldn't bother. That would only give me 35 mph (56 kph). Could do better than that with an off the shelf clone, Briggs, or Tecumseh.
So far, I have hit 42 mph (parking lot) and is nowhere near top end.