On this episode of Project Stoopid we are addressing a decision regarding gearing.
Ya know that fun stuff with chains, sprockets, teeth and math.
Here's the situation:
This machine that became the engine donor had wheels/tires with a 26 inch OD.
The stock gearing is 16/46 or 2.875:1
The bike had a claimed top speed of 140mph. Weather that is accurate or not, doesent matter. Its way way way beyond what i need.
The wheel/tires going on the buggy are also 26 inch OD.
So on paper the top end is about the same, untill the weight figgers in. So even if it looses 40mph its still too much.
Here is where it gets ,interesting.
The original plan was to use the stock sprockets. Screwing with the final drive ratio too much is going to affect driveability.
A little lower might be good, given the extra pork we be hauling 'round.
So l got a 15 tooth drive sprocket.
The driven sprocket has to be replaced cuz i cant find a piece of material to make a hub outta. The OEM hub/sprocket is, well i need a piece of material 7" OD x 3/8 for a flange and mo thicker stuff for a hub.
So plan B:
This hub.
https://www.nitrochain.com/1-12-finished-bore-x-weld-on-hub#mz-expanded-view-1378803706043
And this sprocket.
https://www.nitrochain.com/5048x-weld-on-sprocket#mz-expanded-15view-479000988507
Choices:
16/46 =2.875 stock
15/45=3.00
16/48=3.00
15/48=3.20
16/50=3.125
So, since i need a new driven sprocket i can order anything. I'm leaning towards option c 15/48 for a final ratio of 3.2
That lowers the ratio a bit from stock, without going so low that the first few gears become useless.
The options for the driven spocket are,
44, 45,48,50 tooth.
- I only want to buy one cuz its about $60 so l needto get it right. The driver is a special cuz it has to fit the Yamaha output shaft.
So l'll pose the question to our panel of experts. What ratio?
