Has anyone

[TheCaveman]

Has anyone built the mini bike transmission shown in the off road mini bike plans on the main website? I don't wanna spend the cash on a torque converter if possible haha!

Thanks!

 

[Blazkowiez]

You can always run a dual clutch set-up on a mini-bike if you wanted.

 

[OzFab]

I'm a bit confused with that design; is it meant to shift on the fly? If so, how? Can anyone explain these plans?

You can always run a dual clutch set-up on a mini-bike if you wanted.

Please explain...

 

[cumminsbayou4x4]

how could you run a duel clutch

 

[Swabbster]

wanna buy this clutch from me, 30 bucks plus shipping, it runs a standard v belt, works just like a torque converter

 

[Swabbster]

here is another set of plans, i build on of the bikes, a 2-3hp briggs fits, not sure about a 4hp, 5 will fit but the plug hits, not fun while lining up the sprockets, a honda gx120 will not fit the gas cap contacts the frame, gx160/200 will not fit its too tall, a Tecumseh 3 or 4 hp is what they say to use in the plans, on my bike i bent the forks like the doodle bugs are so my legs would not hit, the bike is very small, id recommend making the frame longer and taller, it took me two days to get mine going dround up build to first test ride without brakes, http://www.sfu.ca/~jst4/plans/docs/bikes/Wren Mini Bike Plans.pdf
http://www.youtube.com/watch?v=BIXe0hG5qig
http://www.youtube.com/watch?v=MmJUvqjAGeI&feature=channel&list=UL
http://www.youtube.com/watch?v=XCA84QAcfZc&feature=channel&list=UL

 

[TheCaveman]

I'm a bit confused with that design; is it meant to shift on the fly? If so, how? Can anyone explain these plans?

I don't believe that it is meant to shift on the fly...

Anyways the reason that I was looking at this is because I want to build an off road mini bike and my land has quite a few(not very steep though) hills and I don't want to burn up a clutch, and I also want to be able to haul game(maybe, i could just come get it with my ranger). btw swabster that works just like a torque converter? I may be interested send me pm!

THanks!

 

[r97]

I'm a bit confused with that design; is it meant to shift on the fly? If so, how? Can anyone explain these plans?




Please explain...

The off road mini bike plans on the main website have a transmission similar to that of your average drill press. Slacken the belt, move the pulley over, place belt back on the pulley, and let go. The way the system is setup in the plans you cannot shift on the fly. That said, I bet someone could figure out an over complicated jumble of cables, springs and levers that would allow you to shift on the fly.

When Blaz says dual clutch jack-shaft I believe he is referring to what I call a two speed jack-shaft. Looking at the picture below, from left to right.

-First is a pillow block bearing.
-Next is a clutch drum that is fixed to the jack-shaft.
- After that we have a cent clutch (inside of the drum) which is riding on bearings and has an engagement speed much higher than standard.
-Next to the clutch is a sprocket that is fixed to the clutch and rides on bearings running over the jack-shaft.
-Then there is a second sprocket which rides on one-way bearings connected to the jack-shaft.
-Finally we have a spacer, a normal sprocket keyed to the jack shaft, and another pillow block bearing.

The engine powering this has a cent clutch with 2 identical sprockets on it. One chain goes from engine clutch to jack-shaft clutch, and a second chain goes from the engine clutch to the largest sprocket on the jack-shaft.

How it works...

Engine revs to 1800rpm and clutch on engine shaft begins to engage. Both sprockets on engine clutch begin to turn, forcing the first two sprockets on the jack-shaft to turn. The smaller of those two sprockets turns the clutch (usually at 1:1 ratio), but does nothing else since the clutch it's turning has not yet engaged. The one-way sprocket is also being turned by the engine, the one-way bearing engages and the jack-shaft begins to turn (also causing the wheel to turn). Since the one-way sprocket is large, it provides lower gearing.

As you gain speed, the engine revs higher, once it reaches a certain speed the clutch on the jack-shaft engages the drum locket to the jack-shaft. Since the clutch on the jack-shaft is driven at a 1:1 ratio, and the one-way sprocket is driven at ~2:1 the clutch is trying to spin faster. When the clutch starts to spin the jack-shaft faster the one way bearing in the other sprocket disengages, allowing the jack-shaft to be driven by the engine through a 1:1 ratio, thus increasing top speed.

When you approach a hill, the engine bogs, the jack-shaft clutch disengages, the one way bearing engages, and you once again have lower gearing. This system is an automatic 2 speed transmission for you min-bike or go-kart, so it allows higher speed, and better take-off than a standard clutch. I really like these systems, and I would love to use one someday. If you think about it for a while, you would be surprised to see how many different configurations of this system can be thought up. You could make it use more standard components, or even make it a 3+ speed!

Hope all that makes sense, let me know If I can clarify anything for you.

 

[TheCaveman]

I might just go with a torque converter, other options seem like they wont save me much money anyway haha

 

[Blazkowiez]

Good job r97. You get the thanks for saving me 10 min of my life.