Mini With 125 Yamaha Engine Project

G-REX · 07-07-2008, 10:41 AM

New project,it might or should not be on OMB forums,but it's a mini project in my eyes.Any way here's the start of project.125cc engine,custom bars and triple trees,everything is tacked up ,but need to change a few things,(right side for exhaust pipe mounting.More pics to come. Thanks.

smallbikes88 · 07-07-2008, 11:14 AM

you might want to change the rear sprocket or you'll be doing wheelies in all gears

G-REX · 07-07-2008, 11:38 AM

Yea,I have 3 or 4 sprockets from tt500s ,I'm not sure how many teeth to use yet.

jesse8931 · 07-07-2008, 02:05 PM

no the bigger the sprocket more top speed the smaller the sprocket more acceleration

G-REX · 07-07-2008, 02:17 PM

If you are talking about the rear sprocket,it is opp.The larger the back sprocket the better the torque for hill climbing.That's what we used to do for our climbing big bores.

**Strigoi** · 07-08-2008, 05:19 PM

Quote:

Originally Posted by jesse8931

no the bigger the sprocket more top speed the smaller the sprocket more acceleration

you've got that backwards for the rear. bigger = more accelleration, smaller = more top speed.

jesse8931 · 07-08-2008, 06:29 PM

Quote:

Originally Posted by Strigoi

you've got that backwards for the rear. bigger = more accelleration, smaller = more top speed.

no you do. think of it a bike ok a bike with 24 inch tires has more surface area so it can travel a longer distance with 1 revolution and take a bike with 12 inch tires it would take 2 revolutions to go the distance the 24 inch tire can. now think of the tires as sprockets

**Strigoi** · 07-08-2008, 06:45 PM

a smaller rear sprocket will make the rear tire turn faster than a larger sprocket.

you'll have a higher top speed with a 60t sprocket than you would with a 72t.

think about riding a bicycle with gears. to go fast, you want to choose the smallest gear in the back and the largest in the front.

**jimh** · 07-08-2008, 06:56 PM

If you had two bikes with the same size tires, the 60 tooth would be faster than a 72. On two bikes both with 72 tooth sprockets,one with larger tires would be faster.

**Strigoi** · 07-08-2008, 08:19 PM

Quote:

Originally Posted by jimh

If you had two bikes with the same size tires, the 60 tooth would be faster than a 72. On two bikes both with 72 tooth sprockets,one with larger tires would be faster.

exactly.