Gear Ratio And Speed

[bernard@pseservices.co.za]

I AM BUILDING A CART FOR MY SON. I HAVE A KOHLER K301 12Hp ENGINE WITH A MAX OF 3600RPM'S. I WANT TO USE THIS TO DRIVE A HOND MB5 GEARBOX WITH RATIOS THROUGH GEARS 1-5 OF 3.083, 1.882, 1.400, 1.130, 0.960 RESPECTIVELY. WHAT SPROCKETS DO I HAVE TO USE? I HAVE 11X22X9.5" QUAD TYRES AT THE REAR.

 

[Russ2251]

Wow...South Africa.
MB5's really rare.
If memory serves, this bike utilized a 49cc engine rated at 7hp. The Kohler will (probably) tear apart gearbox. I would use largest diameter sprocket possible and still have it retain ground clearance.

 

[2or3wheels]

yeah with OD you should go with a 60. I dont kno what that gear box came off of but if it was a lil scooter, or evena 2-stroke watch out it might break.

 

[Russ2251]

I strongly disagree with Mr. Wheels. A 60 tooth sprocket is just too high and will place even more loads on an already overloaded gearbox. Again, I would recommend the largest sprocket rear wheel can handle. If it's 72 tooth...then use that. Watch clearance, especially if if its over 72 tooth, as you don't want sprocket to hit rocks before tires do.

I dont kno what that gear box came off of but

Bernard stated:

I WANT TO USE THIS TO DRIVE A HOND MB5 GEARBOX

It's clear that this bike is little more than a moped with a gearbox. Very light. Kohler engine produces 42% more power than this gearbox was designed to handle.

 

[2or3wheels]

But with that ratio it wont have a great top speed. 1169 is the out put shaft ratio on the lowst gear that would give a top speed of 14 in 1st. If anything go with a jackshfat and get the equilvent of a 80 tooth sproket, you wont loose ground clearence and will make shorter chains for less streching. I looked at the gear box the wrong way i think it would be best to go jackshaft or big sproket.