Chain and sprockets

[JohnT]

Can as someone please advise what the standard sprockets are for a 1979 CB750K, and revs at 100kph? I have a police spec with a 45t rear and a 530 chain.

 

[SenseAmidMadness]

From what I can find for that 530 chain, your bike came stock with an 18t front and a 48t rear.

45t rear would mean your gearing is slightly taller than stock, by about 7 percent. I can't tell you exactly what that means in revs per minute for any given speed but yours should be 7 percent lower than stock at all speeds.

 

[JohnT]

From what I can find for that 530 chain, your bike came stock with an 18t front and a 48t rear.

45t rear would mean your gearing is slightly taller than stock, by about 7 percent. I can't tell you exactly what that means in revs per minute for any given speed but yours should be 7 percent lower than stock at all speeds.

Thanks, I need to look at the front sprocket as well, but are you suggesting it might be 17 or 18? Here I am thinking it is reving too high, obviously too used to my 1200 GS boxer.

 

[SenseAmidMadness]

It's a dual overhead cam inline four -- it makes the most power way up the tachometer. You can decrease your overall gear ratio but it will be at the cost of acceleration. Choose wisely!

A 1t difference in the front won't be huge from your current ratio though. You could certainly try 17/45 and see how you like it.

I own two Boxers and they're different from my CB750K in almost every single way except having two wheels. My R1100RT is happy on the interstate and my R850R has to be at 4,000 RPM to even hit 65. Both accelerate about the same though. Their different final drive gearing makes quite an impact.

 

[JohnT]

Thanks for that, that is very helpful, I’ll ride it a bit longer and enjoy the sound more, because it’s got that all over the boxer engine. The odd part is I started on a CB650C, but that was a long time ago.