Sprocket Question

[CB750K603]

My current set up is 18/46, which I believe is the stock set up for an 82 750K.
If I drop the rear sprocket to a 43, would I have to take a link (or two) out of the chain?
Can someone explain how to calculate this so we can all learn?   Thanks

[Rodgil]

If the sprocket is three teeth smaller, you should remove the same number of links (three). First check if you can take up the slack by adjusting the chain, if not, removing anywhere between two and four links should be ok.

[Re-run]

I am not sure if that is accurate. Only reason is say this is that when you remove 1 link, you actually remove 2 links and 2 rollers. you have to in order to stay with a male/female end for joining. And I think that in the average 530 chain, that removes between 2 - 3 inches of chain. I would have to measure the amount it removed from mine as I kept the links I removed.
You could be right though.

[Rodgil]

Yes, it is easy to remove an even number of links. On my 1982 CB750 I went from 46 down to a 40 tooth sprocket. Six less teeth, removed six links. That is why you would have to remove two or four links, if you reduce by three teeth.
Cheers,

Rod

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From: Re-run [via Honda CB750'S] <[hidden email]>
To: Rodgil <[hidden email]>
Sent: Wed, 16 June, 2010 11:18:42 PM
Subject: Re: Sprocket Question

I am not sure if that is accurate. Only reason is say this is that when you remove 1 link, you actually remove 2 links and 2 rollers. you have to in order to stay with a male/female end for joining. And I think that in the average 530 chain, that removes between 2 - 3 inches of chain. I would have to measure the amount it removed from mine as I kept the links I removed.
You could be right though.

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[ccRider246]

I have an 81 750F. The stock sprockets were 46/18 (2.56 ratio). When I went to replace the sprockets and chain last year I ordered the same (46/18 with 108 link chain). Sunstar didn't have a 46 and mistakenly sent a 42. I talked to my Honda Doc and he advised me to go down a tooth in the front to stay as close a possible to the original ratio. So I changed to a 42/17 (2.47 ratio). In doing so, I had to remove one link in the chain (which, in reality, is 2 links as previously pointed out). If you are not changing your front sprocket you may not need to take out that link . If you're getting a fixed link chain, test it before taking out a link. If your adjusters are too far back take out a link. I was trying to keep my adjusters as tight as possible knowing that the chain will stretch and teh sprockets would wear down in time.

By the way, I am running about 500 rpm lower at highway speeds than previously.

[CB750K603]

My goal is to take down the RPM's @ highway speeds. If I could find a front sprocket higher than an 18 (not sure these are available) I would simply do that. I have dual sport bike and by going from a 16 to a 17, I reduced RPM's by 500 @ 70mph.

[ccRider246]

Check out this site. Gear commander You can select your bike and it will load the standard stock info. Then you can enter what mods you want to make to the sprocket size and check what the RPM effect will be.
Neither JT nor Sunstar has a front sprocket larger than 18 listed for this bike but you could go down to a 40 in the rear, maybe even smaller.

[jrhill]

It's a given that you'll have to shorten the chain.  So mount the sprocket and fit the chain afterward...  Any beforehand calculation would also have to consider the previous position in the adjuster.  Seems more like a winter time discussion over a six pack or two.

[CB750K603]

jrhill, you obviously have clear insight to the situation at hand. Oh, and your advice on fitting chain after mounting the sprocket sounds good too!!!!

[Re-run]

Well that website is being added to our parts list! It is not quite accurate on stock bikes but that is easy to compensate for.