Sprocket/Chain sizing

theillrohan · Jul 13, 2016

I threw a tao tao 110cc engine from my sons quad into his elec. dirt bike frame. The engine has a #420 left hand drive sprocket and the rear wheel (now has) a #420 right hand driven sprocket. I'm using an intermediate axle with a pair of small sprockets to make the transition from one side to the other.

The problem I'm having is with the sprockets on the intermediate axle. I cannot find a #420, 3/4" bore sprocket. I have installed two #40 sprockets that seem to be too thick for the #420 chain.

If I'm correct... The pitch for both is the same (1/2") but they each take a chain with different roller diameters.

Here's my question. Can I take the #40 sprockets to my bench mounted belt sander and take off 1/16" to make it work with the #420 chain or would the difference in roller diameter also F me up?

Iron John · Jul 13, 2016

It might be easier to make or buy two 3/4" to 1" bushings.

chancer · Jul 13, 2016

This is from Yesterday some very goood insight to your questions.
But be sure to read to the end. there was some discussion beefore the real answer came in the end.
http://www.diygokarts.com/vb/showthread.php?t=33505

theillrohan · Jul 14, 2016

Ok so it looks like it will not work properly. So now my next question is, where the heck can I find a #420 sprocket
with a 3/4" bore?
Btw, thank you all so much for the time and advice.

ezcome-ezgo · Jul 14, 2016

How many teeth?

theillrohan · Jul 14, 2016

Iron John said:
It might be easier to make or buy two 3/4" to 1" bushings.

A bushing is made to reduce sizes. I would need to increase to 1".

So my next question is, where the heck can I find a #420 sprocket with a 3/4" bore. They seem to have every other size sprocket/bore combination but the I've I need.

---------- Post added at 07:06 AM ---------- Previous post was at 07:03 AM ----------

ezcome-ezgo said:
How many teeth?

12 teeth, can be a little different. 12 is just what I was able to find. The gearing isn't detrimental

Iron John · Jul 14, 2016

theillrohan said:
A bushing is made to reduce sizes. I would need to increase to 1".

Yes, reducing from 1" to 3/4". Use 1" sprockets. Tomato - tomahto.

Poboy kartman · Jul 14, 2016

theillrohan said:
A bushing is made to reduce sizes. I would need to increase to 1".

So my next question is, where the heck can I find a #420 sprocket with a 3/4" bore. They seem to have every other size sprocket/bore combination but the I've I need.

---------- Post added at 07:06 AM ---------- Previous post was at 07:03 AM ----------

12 teeth, can be a little different. 12 is just what I was able to find. The gearing isn't detrimental

Well...You lost me there FOR SURE! The BUSHING would REDUCE the size of the 1" sprocket to fit a 3/4" shaft....someone is missing something here....and I have a sneaking feeling it's not me or IJ....

theillrohan · Jul 14, 2016

Poboy kartman said:
Well...You lost me there FOR SURE! The BUSHING would REDUCE the size of the 1" sprocket to fit a 3/4" shaft....someone is missing something here....and I have a sneaking feeling it's not me or IJ....

It was suggested to me that I use a bushing to go from 1" top 3/4". I have (included in my original post) mentioned that I have a 3/4" sprocket/axle.

ezcome-ezgo · Jul 14, 2016

http://www.ebay.com/sch/i.html?_fro....H0.X41BS12+3/4.TRS0&_nkw=41BS12+3/4&_sacat=0

theillrohan · Jul 14, 2016

I get it now. The suggestion was that I use a 3/4" x 1" bushing AND ALSO use new 1" sprockets. I didn't catch the inference. My bad.

Poboy kartman · Jul 14, 2016

theillrohan said:
It was suggested to me that I use a bushing to go from 1" top 3/4". I have (included in my original post) mentioned that I have a 3/4" sprocket/axle.

And your point is?

You put the lime in the coconut....why ....oh why...won't putting a bushing in a 1" sprocket to make it fit a 3/4" shaft NOT WORK?

I would delete this...since you got it...but ...JIK...for future reference....

That idea is not without it's snafus however...are these keyed sprockets?

itsid · Jul 14, 2016

there are..

420 has the exact same roller dimension as #41..

so a #41 B type sprocket is what you'd need

go there... scroll down to B-Type and you'll have it

https://www.gokartsupply.com/sprocket.htm

3/4" B-Type Sprocket (10, 12 or 14 teeth) for 420 chain $14.50

'sid

theillrohan · Jul 14, 2016

41BS12
What does the 41 represent? Bc the sprockets I have now, aside from being too thick, are also 1/2" pitch but the roller size is off as well. Is there another number or designation for a size #420??

---------- Post added at 07:28 AM ---------- Previous post was at 07:26 AM ----------

Poboy kartman said:
And your point is?

You put the lime in the coconut....why ....oh why...won't putting a bushing in a 1" sprocket to make it fit a 3/4" shaft NOT WORK?

I would delete this...since you got it...but ...JIK...for future reference....

That idea is not without it's snafus however...are these keyed sprockets?

Again, the original suggestion didn't mention anything about getting new sprockets. I'm at work and just didn't make the connection. That's all. I get it now.

---------- Post added at 07:31 AM ---------- Previous post was at 07:28 AM ----------

Sprockets are NOT keyed. They have two set screw. I planned on marking their location on the shaft and creating an indentation for them to lock in to.

Poboy kartman · Jul 14, 2016

41 represents pitch as in #41.

It's a little confusing....but #41 sprockets are thinner than #40.

itsid · Jul 14, 2016

theillrohan said:
41BS12
What does the 41 represent? Bc the sprockets I have now, aside from being too thick, are also 1/2" pitch but the roller size is off as well. Is there another number or designation for a size #420??

---------- Post added at 07:28 AM ---------- Previous post was at 07:26 AM ----------

Again, the original suggestion didn't mention anything about getting new sprockets. I'm at work and just didn't make the connection. That's all. I get it now.

---------- Post added at 07:31 AM ---------- Previous post was at 07:28 AM ----------

Sprockets are NOT keyed. They have two set screw. I planned on marking their location on the shaft and creating an indentation for them to lock in to.

41BS12 3/4 means:
#41 chain,
B Type Sprocket, (sprocket on the edge of the hub, not centered (C type) nor without hub (A type))
(S means with setscrews I guess)
12 Teeth
3/4" finished bore

#41 chain is the weakling brother of a 420 chain
they have the same dimensions (420 uses thicker pins and sometimes thicker plates... that's it!)
they both use the exact same sprockets to run on.
(pitch, inner width and roller dimensions are identical)

So if you see a sprocket made for #41 chain.. you can run your 420 chain on it without problems.

The Sprockets I linked you to are all WITH a keyway (without inbuild key though) so you'll have to add your own key just like with the one from martin here:
https://www.motionindustries.com/productDetail.jsp?sku=00169135

(basically that's the exact same thing.. just more expensive

'sid

ezcome-ezgo · Jul 14, 2016

I thought BS means "bored to size". Maybe just the S means that.

itsid · Jul 14, 2016

ezcome-ezgo said:
I thought BS means "bored to size". Maybe just the S means that.

Just S makes sense...

Again Martin sprockets... WITHOUT S
A type:
41A20 Sprocket - 5/8 in Rough Stock Bore
B type:
41B12 Sprocket - 1/2 in Rough Stock Bore
C type:
40C12 Sprocket - 1/2 in Rough Stock Bore

all rough stock bores... actually plausible "S" stands for "sized" bore...

I can't tell since all "sized bores" have setscrews as well...
even the ones without keyways

*shrugs*

But "B" -I'm certain- denotes the sprocket type (as seen above)

[an "H" on the end would mean hardened teeth]

On all pages I checked it's impossible to find sized bores for anything but B types... *shrugs*
(or they have non pattern matching partnumbers)

'sid

theillrohan · Jul 16, 2016

"Thank you" to everyone. I was really confused about chain/sprocket sizing and this thread lent a LOT of clarity. Idk why some places call it #420 #425 etc. and other people call it #35, #40, 41 etc. Whatever the reason, I WAS confused and I'm less so now. The correct sprockets arrive tomorrow. I'm going to mount everything up and link up the chains. I'll put up some pictures after I do. I'll need to make chain tensioners and a battery mount before it's complete but I'm on my way now.

---------- Post added at 06:56 PM ---------- Previous post was at 06:24 PM ----------

---------- Post added at 06:59 PM ---------- Previous post was at 06:56 PM ----------

http://www.diygokarts.com/vb/attachment.php?attachmentid=72928&stc=1&d=1468724078

Poboy kartman · Jul 16, 2016

theillrohan said:
"Thank you" to everyone. I was really confused about chain/sprocket sizing and this thread lent a LOT of clarity. Idk why some places call it #420 #425 etc. and other people call it #35, #40, 41 etc. Whatever the reason, I WAS confused and I'm less so now. The correct sprockets arrive tomorrow. I'm going to mount everything up and link up the chains. I'll put up some pictures after I do. I'll need to make chain tensioners and a battery mount before it's complete but I'm on my way now.

---------- Post added at 06:56 PM ---------- Previous post was at 06:24 PM ----------

Maybe....maybe not...those are all different sized sprockets and chains....they ARE standardized....

Sprocket/Chain sizing

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