Need help on my motorized bike

[Shergernetic]

Hi guys I have a motorized bike that I've build but it doesn't run right I got my gear ratio wrong and I need your help I'm planning to use a jack shaft but don't know what size of sprocket to use so please help me out
Engine is a 3hp
Clutch is a 11 tooth #41
Jack shaft sprocket is a 44 tooth then goes to a 28 tooth
And then Mountain bike sprockets in the back
The wheel is 2 feet

Here's a video
http://www.youtube.com/watch?v=c24xGvIHkm8&feature=youtube_gdata_player

 

[Shergernetic]

I'm also new here so I don't know if this is the right formula so sorry if it is

 

[landuse]

Are you using the original sprocket on the back wheel? As far as I know, those sprockets aren'y made for #41 chain. Could you post a pic or two of your setup?

The way i work it, your gearing going into your jackshaft is 44/11 = 4. On the jackshaft out side you need to divide your back wheel teeth by the 28 coming out of your jackshaft. You then take that figure and multiply it with the 4 that you originally got. This will give you your gearing ratio. You should probably use a ratio of 14 or 15 to 1. This means that you are going to have to have a really large rear sprocket

 

[Shergernetic]

Will the thing is that I wanted to ride and shaft gears I've seen poeple on YouTube that did that but they buy some kind of kit that comes with motor and sprockets
I was wondering it I got and another jack shaft between the clutch and the sprocket in the bottom (other jack shaft) say a 28t and a 11t or some thing will it work?

 

[Shergernetic]

The #41 chain is only on one side (motor) the original chain is on the other side(wheel)

 

[Shergernetic]

So I don't get gearing ratio what is 15 to 1 and I'll take more pictures after I get off work

 

[Bluethunder3320]

that means the engine has to turn 15 times to make the wheel turn 1 time

 

[kendelrk]

ratio, (not real numbers) well say a dime is 1 inch, and a quarter is 2 inches, the dime has to turn two times to move the quarter once

 

[B-Well]

if you use 11clutch to 44jackshaft (44/11=4/1 ratio) then use the 28jackshaft to 84 on the wheel (84/28=3/1 ratio) then multiply your reductions together (4*3=12) final ratio is 12/1.

once you reach full RPMs on the motor you will be at roughly 20mph

 

[Shergernetic]

The thing is I want to shaft gears so if I put a jack shaft between the clutch and the sprocket on bottom what will I need


Motor is a 3hp
Clutch is 11t #41
Bottom sprocket (right side) is 44t
Bottom sprocket (left side) 28t
Sprockets on rear wheel 28t to 14t the wheel is 2 feet tall
It weights about 40lbs I'm at 210lbs

 

[Shergernetic]

How do I post picture on here do I have to upload it to photobucket first

 

[Shergernetic]

Motor and bottom sprocket (right side jack shaft)

Bottom sprocket(left side jack shaft) to rear sprocket

On this picture the right is the motor side left side goes to the rear wheel

 

[landuse]

I think I might be a bit out of my depth here, but why don't you sign up at www.motoredbikes.com/index.php. This is their speciality, and they will be able to help you out in no time.

Just to make sure....you want to shift the gears on the back wheel, not the jackshaft out. Is that correct. I am just asking cos the JS out side also has a few sprockets there, and I don't think you will be able to change them.

 

[Shergernetic]

Great thanks I'll sign up with them too and yes I do want to change gear on the back wheel