Help keeping the chain on my sprocket

[japat100]

better read again and take advice what 5-7HEAVEN has posted ,,

why try keep your chain on ,this setup will only burn out your clutch ,, you were lucky when you gave it more throttle that it did not sick on ,,because if your motor ever got up to 8,000 rpm you would have been going 220 mph ,

you got to gear down ,and when you do your clutch will be fine ,,these power saw clutches are very good and should last a long while ,, like i say read 5-7-heaven post again
japat

 

[MisterSteve124]

I know but if you look at the pictures I can't think of how I could set up a jackshaft there's not much room, any ideas? I found a jackshaft that I might be able to get to work but what size gears should I use for the two?

 

[srdavo]

this is ugly....but functional.... 37 mph
http://www.motoredbikes.com/attachment.php?attachmentid=1687&d=1190550102

http://www.motoredbikes.com/attachment.php?attachmentid=1686&d=1190549681

http://www.motoredbikes.com/showpost.php?p=78789&postcount=47

 

[MisterSteve124]

That sorta looks like what I am now thinking about doing, except I don't think I can use 2 jackshafts. How do I calculate the gear ratio with 4 gears. I found jackshafts with a 10 tooth sprocket and a 14 tooth sprocket and one with a 13 tooth sprocket and an 18 tooth sprocket. Maybe I could buy the 18 tooth one and buy a 10tooth sprocket and use that or vice versa with the 10 tooth and buy a bigger sprocket. But what would be good sizes? And should I be looking at a 3/4" shaft or 5/8" or does it not matter. I'm hoping that I can just get the bearing hangers welded on either side of the rack mount and then get two bars reinforcing the bike rack to the frame so it can't flex as much. Get what I'm saying or should I draw something up in paint? Thanks for all your help guys

 

[5-7HEAVEN]

Now you're thinking, Steve!

Let's compare your setup with a happy-time engine with 41-tooth rear sprocket. with its 10-tooth engine sprocket, that computes to 4.1:1. multiply that to the engine's built-in gear reduction of 4.1:1, and you get 16.81:1.

that's your final drive goal...on or about 16.81:1.

your 36t driven sprocket will link to a 8t on the right side of your new jackshaft.this results in 4.5:1 ratio. dividing 16.81 by 4.5 gets 3.74:1. on the left side of the same jackshaft, slide a 30t sprocket. change your engine sprocket to 8t, which then links to that 30t jackshaft. this ratio is 3.75:1.

with 16.81:1 as your goal, you have 36t/8t(4.5:1) and 30t/8t(3.75:1). multiply 4.5 X 3.75 = 16.875:1...an EXTREMELY close match.

your new combination of gear ratio will duplicate the mph/engine rpm comparison chart i posted earlier.

Sooo, you'd have an 8t engine sprocket linked to a 30t jackshaft sprocket, left side. an 8t jackshaft sprocket is on the right side, which is aligned and chained to the cassette's 36t sprocket.

if you're able to aquire these exact-sized sprockets(not 9t,10t,28t,29t sprockets), you would be able to gear down, using just one jackshaft.

because the jackshaft will be short and chain tension relatively light, i think that 5/8" shaft is sufficient.

always remember that the engine AND the jackshaft will need independent adjustability.

now go look for those gears. You will not find this combination in a universal $30 kit. each piece must be individually selected, and are available at various websites. unsure about the 30t sprocket with 5/8" bore.

and be sure to get the matching chains. you MIGHT have a problem finding a sprocket and chain to match the 36t cassette driven sprocket. if you can't find a thin-enough sprocket to fit the bicycle chain, i've heard that BMX chains might work. if not, ya might have to machine the teeth of the 8t sprocket narrower, to fit the bicycle chain.

Myron

 

[MisterSteve124]

The only problem is I can't change the engine sprocket. I got it welded onto the outer clutch housing. Is there any way I can still get a good gear ratio using the 13 tooth?

 

[5-7HEAVEN]

That changes the combinations, and forces you to use TWO jackshafts.

Okay, 13t engine sprocket/22t jackshaft sprocket, right side. left side sprocket, same shaft, is 8t. second jackshaft, left side is 18t; right-side sprocket on second shaft is 8t, and is aligned directly with 36t wheel sprocket.

now, 22t/13t=1.69:1
18t/8t= 2.21:1
36t/8t=4.5:1.

1.69 X 4.50 X 2.21 = 16.81, the EXACT final drive goal you were shooting for, and comparable to happy time/41t.

for more low-end, change 18t to 20t.comparable to happy time/46t.

for more top end, change that same 18t to 15t. comparable to happy time/35t.

Myron

 

[japat100]

one thing is to check to see what hp you are running ,,power saw could have more cc then happy time ,,so you may get away with a little less reduction and 1 jack shaft
japat

 

[5-7HEAVEN]

The most logical method is to find out at what rpm does maximum hp occur, and gear your bike's maximum speed accordingly.

or for riders interested in low end torque, find out at what rpm does maximum torque occur, and stay in that rpm range.

Myron

 

[MisterSteve124]

Can't I get close with just one. I don't have the money to just be buying 2 jackshafts. What if I just get like a 10 tooth sprocket and a like 30 tooth sprocket or something. How close can I get with just one jackshaft and my 13 tooth drive sprocket? Ok I get that I can't really just use 1 jackshaft unless I get like a 38 tooth sprocket to use or something that will probably be way too big. I can't find a 22 tooth sprocket though. There are 20's but I can't find a 22. What size should I get if I need to use with my bike chain. I'm almost positive it's not 35 I was thinking maybe 40 or 41. Anyone have any idea? and do you think it would be ok just to attach the jackshaft by getting the bearing supports welded directly to the bike rack?