New Chain and Sprockets

[TwoWheelThom]

I've been having a little trouble picking a new chain and sprockets on my cb750.  Its a 1979 limited edition 10th anniversary frame with the 1977 sohc engine, which reads cb750E.  The current sprockets are 18 teeth on the front and 48 on the back.  I figure that the sprockets would be stock for the 1977 model, but when i look them up, i find that the stock sprockets are:
1977 cb750F: 14-43 teeth
1977 cb750K: 15-41 teeth.  So i checked the 1979 and found
1979 cb750F: 15-38 teeth
1979 cb750K: 15-38
1979 cb750L: 15-38.  So i guess i havent been running stock sprockets, and i really like the way the bike has been running so i dont know how changing to stock sprockets would affect that.  Could someone advise me on the right sprockets to get for this bike and what the change in performance might be?  As far as the chain goes, i've found it to be a 630 but does anyone recommend a specific chain, or if i should get an o-ring or what else.  I dont race but i ride medium hard so i dont need a real expensive one but i dont want a cheap chain either.

Thanks a lot, i really appreciate any help!

[Leerider]

I have 78~75OF it has 63O chain, this is good. 15~41 sqrockets,45~47 MqG. I just but a new O ring chain on my bike,about $1OO~$12O.Iam haqqy with it. RIDE SAFE ~ LEERIDER ~

[gonebiking-2]

I have a 1981 CB750K which was factory fitted with a 15 -44 set up. Great acceleration and reasonably good fuel consumptiom at around 42-45 MPG. I changed sprockets and chain after the genuine Honda sprockets/chain were completely worn out after some 6,000 miles. I replaced the rear sprocket with  40 teeth, and despite some problems with starting on hills and two up, she runs a 1000 rpm less at higher cruising speed. The rev counter rarely sees 4500 RPM at 130-140 KMH ( 80 - 90 MPH ), but performance has dropped. As I am doing a ground up restoration I am going back to a 15 - 44 set up again and that sould suit the bike just fine. There are many different sprocket set ups, but it also depends what the ratios in the gearbox are.

[Lucky 1]

Why not use a 530 chain and get rid of some of that weight?


use a steel sprocket on the front and a aluminum sprocket on the rear.

Get rid of that heavy rear sprocket and the aluminum rear sprocket will only be about 2.5 pounds.

[TOOLS1]

That's some good advice. It would surprise most people to find out how much power it takes to turn that heavy chain, and sprocket.
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[GearBocks]

Totally agree, I have a 82cb750f and rear sprocket is too big I think. When I'm at 60mph in 5th rpms are at 7k. That seems way to high for 60mph, but the speedo says 85max. I would definatly like to turn less rpms at freeway speeds so I'm going to go down a few teeth in the rear, and switch to a aluminum 530 sprocket. That is the way to go. Lighten up rotational mass and gain more top speed.

[Lucky 1]

Select the sprocket ratios based on the engine you have.
I have a 1978 and I was running 17T-43T and it was a bit low.

I now have changed to 17T-40T A bit higher and it should be about right.
You may want to go even higher.

But ask others on the forum.
On California freeways you may need to cruise at 70 mph
in some places to keep up with traffic.

[Piute]

1977 cb750F: 14-43 teeth
  was stk. on mine ,went with n running 15-43 plan to try 1-2 less in back, but enjoy the 630 "O"ring chain since it has only 10 k on it seem to be fine for my use ,less in rear will give me a chance to tear into rear while off also.

[shinyribs]

There is a big difference in sprocket diameter depending on the pitch of your chain.Whether its a 530 or a 640 chain

A 18-48 set up with a 530 chain is a decent setup,but that same tooth count on a 630 chain would be MASSIVE!

Tooth count is not the same as diameter. A 14 tooth 630 sprocket is pretty close to the same diameter as a 530 18 tooth. Be careful to compare apples to apples

[Piute]

  As TO what Ribs was saying ,I don't think a 17T 630 will fit on my bike not enough room.
 There are more choices at using a 520 ,but at what cost ?,does it change much ?
    Good point ChromeGuy,

[shinyribs]

530 stuff I found was cheaper than 630. Cheaper,lighter,more common. Even most of the guys at the dragstrip around here are running 530's . I checkedThere are a few old school hold outs using the monster 630 stuff,even one Kawi running dual chains( looks wicked!) But the late model guys are all running 530 and a few 520 chains. TWIMC

[Piute]

  Well for TwoWheels and other and me being el'cheap'o' ,I like to test different things for myself.Same stk. chain & 15T cost me 13-15bucks total was new gear.Rear will be be 25-40.Then A 530 set will run 120-150 smacks in the azz.Being new to this type of bike,gearing,hole package,getting thing right for yourself has to be tested by you.

[alexargentina]

Hi from argentina
I have a 1981 cb750k and revs are too high for my like
As I bout it used,,, I can read chain is 500S and dont know what this mean
I would like to buy rear front sprockets and o-ring chain and ship it to canada or spain, from there it will come to argentina
But here I can only purchase 18/46 sprockets and this keeps revs too high
May be an 18/42 will be just fine??
ANd where can I purchase this sizes and correct chain?
Can you help?? Ebay, amazon dont shoe this sizes
Can you halp por favor?
Muchas gracias, thanks
Alex

[TOOLS1]

You can use a 530 chain and sprockets off an earlier (69-76) CB 750. Vintage CB750.com has a chart of sprocket sizes that were available on each model. I actually prefer a 530 O-ring chain over the 630 chain that came on your bike. However, do not buy one of those $30.00 chains from eBay. They only last a few thousand miles. Buy a good chain like EK, or D.I.D.
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