2 Speed Belt Tensioner Build

[devino246]

Some of you may have read my original thread on this idea. After some procrastination, im finally starting.

Im using 5" & 9" pulleys for the first gear and 4" & 4" pulleys for second. 2 pulleys will be on the engine shaft and 2 on a jackshaft. A chain will transfer power from the jackshaft to the axle for a final ratio of 6:1 in first and 3.33:1 in second. The kart and I dont weigh that much so the ratios should be perfect. Ill be posting some pics later this afternoon.

 

[freakboy]

yay someone is acctualy doing it!

 

[devino246]

Yep. I probably coulda spent an extra $20 and just bought a used CVT, but whats the fun in that??

 

[freakboy]

its way more fun building something from scratch... after i figure out what ima be doing with my old briggs after i rebuild it i might acctualy try this idea.

 

[devino246]

Got some pics!

The jackshaft is gonna be mounted near the top of those 2 tubes sticking up. Ill be using some angle iron to help support those tubes.

Any idea how many RPM an ungoverned clone could crank out? 5500? Only mods are 18lb springs, straight pipe, high flow filter, and billet con rod.

 

[freakboy]

5500-6500

 

[devino246]

HOLY S#&T. That means if I switch the engine pulleys around, the theoretical top speed would be 70mph!!! Although theres no where i could go over about 40. I cant wait to get this this going!

 

[freakboy]

oh well since its a 2 speed it might have alright exceleration you might have to fiddle with your final drive ratio if it bogs when you change gears.

 

[modelengineer]

Just a thought, in that original diagram on the thread you referenced, it would be easier to make and control (1 lever) if you had it set up so that one belt ran under the tensioner, and the other ran over it. That way if you moved it upwards it would tension one 'gear' and downwards would tension second 'gear'.

That way you just have one lever.

 

[devino246]

Just a thought, in that original diagram on the thread you referenced, it would be easier to make and control (1 lever) if you had it set up so that one belt ran under the tensioner, and the other ran over it. That way if you moved it upwards it would tension one 'gear' and downwards would tension second 'gear'.

That way you just have one lever.

I think i see what your saying, but its best to push the bottom of the belt up. That way theres more belt in contact with the pulleys

 

[devino246]

oh well since its a 2 speed it might have alright exceleration you might have to fiddle with your final drive ratio if it bogs when you change gears.

When i was deciding on ratios, i calculated axle rpm when the engine was at full throttle in 1st when it was reved down in 2nd, then made sure there there was some overlap. That way there would be a fairly smooth shift(in theory).

 

[EagleTalons]

Nothing will ever explain that dead dog in your photo...

 

[devino246]

Nothing will ever explain that dead dog in your photo...

Dead dog? Hes not dead!

 

[Orange Krate]

yay someone is acctualy doing it!

I'm a little verclempt!

 

[AlphaRunner85]

im excited to see how this works for you. i posted about this last year when we got out 13hp honda running. I had worked out the same 70mph top speed and everything. I like your idea for neutral, i figured if there was no tension on the belt there would be no moving, but if there is no pully under the belt it definatly wont move. Keep at it this would be awesome to see someone finish. GOOD LUCK!

 

[devino246]

Thanks. I only have 5 days of school left and most of those are half days so hopefully i can get some work done. Im hoping to get it done in about 2 weeks. Ill be sure to post pics.

 

[devino246]

2 days of school left and i get out early so im starting finally. Hopefully today ill be able to get all the jackshaft supports cut and mocked so ill be ready to weld tomorrow.

 

[devino246]

Got a little bit more done than i expected. No "dead dog" this time EagleTalons:toetap05: Tomorrow ill add some supports and mabe order the pulleys i need.

 

[Rotore]

interesting

 

[freakboy]

wohoo i cant wait to see this thing done dude!