Gear Ratio

[The Repairist]

I am having trouble finding a gear ratio that could fit a 8 hp B&S. The sprocket I would like to have is a 54 tooth sprocket but I cannot figure out what the clutch should be. If anyone helps me, the educated guess of mph would also be very nice.

Thanks for your help(If you help, that is).

 

[itsid]

well first:

the clutch (being the smaller one) is the one that dictates the toothcount of the axle sprocket.
on a 8hp engine we likely talk about a 1" shaft, thus around 14T for a #40 or 420 chain

with 54 teeth on the axle you will likely not move at all but burn your clutch.
depends alot on the weight of the vehicle (incl the driver and passenger[if any])
and the size of the wheels.

if you want to stick with a 54T axle sprocket, you will need a jackshaft setup (maybe even with an additional torque converter) but otherwise you're not going anywhere with such gear ratio.

'sid

 

[The Repairist]

Oh... oops

So should I go for a 72 tooth sprocket on a dead axle then?

 

[The Repairist]

Gear ratio mk 2

Does anyone know if a 72 tooth sprocket will fir on a briggs engine with any given clutch?

 

[bob58o]

Could have kept the same thread going. This is just strange now.

Sprockets for go karts and minibikes generally come in two varieties.

Those for #35 chain (3/8" Pitch)
Those for #41/ #40 / #420 Chain (1/2" Pitch)

If your clutch is #35, then you need a #35 Rear Sprocket.
If your clutch is #41/40/420, then you need a sprocket that is for #41/40/420.

72 T is probably #35 Pitch.

1/2" Pitch sprockets are bigger than 3/8" Pitch sprockets.
The number of teeth on the rear is generally limited by the tire size and how much ground clearance you need.

 

[The Repairist]

Sorry, i'm new to this whole forum thing.

 

[bob58o]

Sorry, i'm new to this whole forum thing.

No problem, some forums like a new thread for each question. Seems that they prefer one thread with all related questions here. It is easier so the same info isn't repeated each time a new question gets asked.

 

[The Repairist]

Thanks, man

 

[itsid]

as said.. weight and wheelsize else there's no way in telling you

'sid

[EDIT]
Also, two threads asking the same incomplete question?
you ARE new to this whole forum thing...
MERGED!

 

[mckutzy]

hello... and welcome...

Howabout some pics as to what were dealing with?...
What is the OD of the tire size...not sidewall size... the actual measured size OD?....

 

[The Repairist]

Tires

The tires are 6'' tires from Go Powersports, sprocket size is 72 teeth, and I can't figure out what clutch size to get to make a good gear ratio.

 

[MTNSleder]

The tires are 6'' tires from Go Powersports, sprocket size is 72 teeth, and I can't figure out what clutch size to get to make a good gear ratio.

How Bow some pics? Its not makin sense

6" is most likely your rim size we want to know your TIRE size

 

[The Repairist]

http://www.gopowersports.com/145x70-6-drive-wheel-assembly/
Here's a link for you then

 

[sefishy]

so you have a 14.5in tire and a 72tooth sprocket? then i would want to start with a 12 tooth clutch to get you at 6to1 ratio on #35 chain. at 3600rpms that will net you 25 or so mph

 

[bob58o]

70 % of 145mm is 4". So a 145/70 - 6 tire is 14", not 14.5".

I hope you didn't say 14.5 inches because the first number is 145. That is the width of the tire in mm. 145mm wide with a 70% aspect ratio. So 4" + 6" + 4" = 14".

---------- Post added at 01:45 AM ---------- Previous post was at 12:54 AM ----------

Time to upload a picture of the kart since you didn't tell us about it.
Sid asked for the weight of the kart and the weight of the driver.

You probably know how much the driver weighs so tell us. If you don't know what kart you have or how much it weighs, then you need to provide us with a picture.


8hp engine with 1" shaft gets this recommendation from me....
30 series TAV-2 kit with 1" Bore Driven Unit.
Not a surprise, I recommend that everybody gets a torque converter.
As a matter of fact, I want each of you to look under your seats right now.

You get a Torque converter and You get a torque converter and you get a torque converter and....
http://www.ebay.com/itm/1-GO-Kart-T...ash=item2c94ca9dc2:g:Mz4AAOSwa39UyqY7&vxp=mtr

---------- Post added at 02:04 AM ---------- Previous post was at 01:45 AM ----------

Every time I read The Repairist, all I think about is Sean Connery from Celebrity Jeopardy.
Sorry I can't read or write properly any more. I just see words as groups of letters now... Probably why I ordered a customer HaBanero Wings instead of HoneyBBQ Wings. They both have an "H" and a "B" - basically identical.

 

[itsid]

thanks bob as I read sefishy's post I thought the same thing (145 is not 14.5")

Well repairist if you do not want to answer the questions we're asking (in order to answer YOUR question correctly) then you will end up with either the wrong or no answer at all!

'sid

 

[The Repairist]

Sorry, forgot to answer that question, I am in the process of constructing one(a go kart that is). So I am unable to tell you how much it weighs.

 

[itsid]

See, that's a statement we can work with.

If you tell us "WHAT" you're going to build we can make an educated guess about the weight based on known karts for example.

But this is all tedious and essentially leads nowhere if you're using pipe instead of tube
Sooo, the correct answer would be:
Do not worry about sprockets too much yet!

First get the chassis, then care about the axle and hubs (get a sprocket hub that accepts a wide range of sprockets .. maybe even split sprockets)
and then, after your engine is mounted, find the clutch you want (maybe a series 30 TC even)
if so pick a 10T #40 rather than a 12T #35 [better chain]
or if you think a cent clutch will do much better for your task, get one of those (the smallest #40 chain toothcount you can find!)
weigh the beast as good as you can, add your own weight and then we can tell you what gear rati and sprocket size will work best for you.

'sid

 

[The Repairist]

Right, thanks, I knew that all along
(thanks, though)

 

[ezcome-ezgo]

This is what I have read so far...

"Hey guys, what's the best way to? I have one and I want to make it."