Topic: What sprocket size you running? CB750

[brandEn]

At the risk of getting flamed I am asking... What size sprockets/gearing you using?

After a few miles on my new build I am thinking the 17T front 48T rear with 630 chain is in need of a change. I don't anticipate much slab time with this bike so I am thinking about changing sprockets size for a bit more pep. Thoughts? Input?

[Gordon]

Going with a smaller rear sprocket will do the opposite of giving the bike more "pep".  You either need a smaller front sprocket or larger rear (or a combination of both) to increase the low-end torque.

[brandEn]

Ah, thanks for the clarification. Now that I think about it that makes sense. Thats why those stunt bikes have those huge rear sprockets.

fixed...

[tweakin]

Dude,  Why don't you at least get more than 50 miles on the thing before you think about changing the gearing.  J/K, 

edit: you are worse than me...

At the risk of getting flamed I am asking... What size sprockets/gearing you using?

After a few miles on my new build I am thinking the 17T front 48T rear with 630 chain is in need of a change. I don't anticipate much slab time with this bike so I am thinking about changing sprockets size for a bit more pep. Thoughts? Input?

[brandEn]

haha, 50 miles? How bout 79.3! Yea get some!

[brandEn]

 And by the way...nobody is worse than you!
 

[wookie]

Break your motor in, get it tuned properly and then think about gearing.  I run a 17/48 520 with no complaints.

J

[Don R]

Way back in the olden days we used a 17 on the front for performance, sometimes with a 50 rear then an 18 / 48 for highway use. If we were pushing a windjammer or a lot of weight we left the 17 on all the time

[MCRider]

The 17/48 combo is usually with a 530 chain. The increase in size to a 630 drops the number of sprocket teeth front and rear. Sure we're talking about the same thing?

In my opinion 17/48 is the best al around compromise, as the stock setup was 18/48. You could go to a 16/48 but you'd be turning alot of revs at highway speeds. Increasing the rear may foul the chainguard, if you're running one.

Wookie: I didn't know there was a 520 conversion either. Sources?

[brandEn]

The 17/48 combo is usually with a 530 chain. The increase in size to a 630 drops the number of sprocket teeth front and rear. Sure we're talking about the same thing?

In my opinion 17/48 is the best al around compromise, as the stock setup was 18/48. You could go to a 16/48 but you'd be turning alot of revs at highway speeds. Increasing the rear may foul the chainguard, if you're running one.

Wookie: I didn't know there was a 520 conversion either. Sources?

Thanks for the input. Yes I am running JT sprockets 17 up front and 48 rear with a 630 DID chain. What ratio is that comparable to with a 530 chain?

[MCRider]

If in fact you have a 17/48, its the same ratio as any other 17/48. The chain size doesn't change the ratio. But your sig says its a 78 750F and they came with a 14/43 using a 630 chain, which is "more power" than a 17/48 ratio.

[wookie]

The 17/48 combo is usually with a 530 chain. The increase in size to a 630 drops the number of sprocket teeth front and rear. Sure we're talking about the same thing?

In my opinion 17/48 is the best al around compromise, as the stock setup was 18/48. You could go to a 16/48 but you'd be turning alot of revs at highway speeds. Increasing the rear may foul the chainguard, if you're running one.

Wookie: I didn't know there was a 520 conversion either. Sources?

Yeah, it was something that cycle x offered at one time.  O-ring chain, decent quality, so far so good.

J

[MCRider]

SNIP
Wookie: I didn't know there was a 520 conversion either. Sources?

Yeah, it was something that cycle x offered at one time.  O-ring chain, decent quality, so far so good.

J

Cool. No reason a modern 520 can't be used. Such a conversion is hot setup on HawkGTs (I have one) and many make a lot more hp than our CBs ever will.  Much lighter.

[TaylorG]

Hmm, I got my 750f running and replaced the rear sprocket and chain with what I thought was the stock sprocket combo: 14/43 630 chain.  I road tested the bike and gearing seems way off.  I'm in second before I'm out of first and at 60, the RPM's are screaming!  Should I look at a new gearing combo?  17/48?  Or do I have another problem?  With the exception of a leaky carb, bike starts, runs and sounds great.  Any thoughts from the forum would be really appreciated. 

[754]

 I am sure its 530 chain, if you have 17/48

 17 /54 is fun on the street, just change to 19 for longer distances..

 Any 530 can be switched to 520, just thin the sprockets..

[Spanner 1]

17/48 K1 750 @ 60 mph 5th. gear = exactly 4,000 rpms....... nice

[Tripps]

?Stock?  78 750K, 4200 at 60 mph.

[Spiider]

17/48 with a 530 chain.

[InAquaVeritas]

I'm bringing this topic back to life a little, since I'm in the process of deciding what front sprocket to get and might as well go with the info here so far. What are the experiences from the option above?

It's 78 F2 engine and I've got a brand new 43 520 rear which I would like to keep if possible. Tire circumference is a little smaller: 2074.7 stock mm vs 1959.7 mm current. It's a 160/60/17 wheel/tire. I'm not sure what to get for the front.

The engine is stock, with a ported head, so I've got a little bit more power. Will be running a bread box style air box, because pods won't work well in wet and windy weather, and the stock one doesn't look too good. I know the bread box is far from perfect and doesn't flow as well as the stock.

The F's came with a 14/43 630, for a little bit of extra power and ran that initially. I liked it, but it's a little high revving on the highway. It will be both a city and highway bike, but mainly highway.

What are the best options? Including changing out the rear, but preferably keep it.

[Bailgang]

My 77 F2 currently has 15/43 with 630 chain. It ran just fine with the 14 tooth front sprocket but I threw the 15 tooth in just to bring the rpms down a bit on the highway but my left foot is still searching for that phantom 6th gear from time to time.

[PeWe]

I liked 17/48 with 530 chain back in the 80's. Even on long touring in Europe
Had it last year but the bike was screaming too much with my load 4-1 so I went back to K stock 18/48. Still very load!

[Spanner 1]

I just did the conversion from ( stock ) 630 chain and 15F, 41R sprockets to 530 chain and 17F, 48R sprockets.... and the final drive ratio is almost exactly the same... on my K8 and love it !

[scottly]

To use a 43 tooth rear, you would need a 15 tooth front sprocket to get close to the same ratio as the preferred 17/48 combo for 5xx series chain. The smaller pitch diameter of a 15 tooth 5xx sprocket is harder on the chain and sprocket than a larger 15 tooth 6xx sprocket. 

[enwri]

?Stock?  78 750K, 4200 at 60 mph.

That's about what I get with a 16 x 38, 630 and 17 inch wheel on my 77 K.
I'm not sure if I could get a 17 front sprocket on, there's not much room left in there.

Approx 80kph/50mph in first, about 2600 at 60kph/37mph,  100kph/60mph  4200, 160kph/100mph at somewhere between 6500 and 7500, depending on when you look at it.

 Was even taller with the 18 inch wheel. 2200 at 37mph, 3800 at 60mph, 100mph at 6000.

At least I don't have to worry about unexpected wheelstands.

(above results were obtained using 35+ year old Honda instruments of unknown history).

Too tall for regular two-up riding, IMO. I'm 70kg and rarely go two-up. Can't go over 6000 (speed limit in first gear,) unless I'm on the highway.

[PeWe]

Use the Excel file to check. Found it on this forum. Rear wheel (with tire) diameter is an important parameter too.
I have added kmh.