Topic: CB550, lookin to go up a few teeth with the rear sprocket...

[rusty_tank]

Hiya guys. I have a 78 CB550. I'm looking to go up a tooth or two with my rear sprocket. I've searched the interwebs and can't seem to find what I'm looking for. It's my understanding that, regarding the sprocket mod I'm talking about, it's up two teeth in the rear and possibly down one tooth in the front. The available sprockets I'm finding for my bike are exactly the opposite. Seems as though rear sprockets with less teeth and front sprockets with more teeth are very available. Any thoughts, ideas, knowledge about where I can find what I'm looking for?

[Retro Rocket]

What do you want, faster off the line or less revs at highway speeds...?

[Deltarider]

Why don't you begin to tell us what you have now? All stock CB550s had front 17 and rear 37. One exception: the CB550K3 in Europe had 34 rear (like the CB500 had). That 4-4 CB550K3 model was marketed as the tourer version of the somewhat sportier (4-1) CB550F2 that was on the market simultaneously.

[mrfish2]

Sprocket Specialists will have everything you need.

[rusty_tank]

What do you want, faster off the line or less revs at highway speeds...?

I want, "faster off the line". It's my understanding this is a fairly common mod, no?

[rusty_tank]

Why don't you begin to tell us what you have now? All stock CB550s had front 17 and rear 37. One exception: the CB550K3 in Europe had 34 rear (like the CB500 had). That 4-4 CB550K3 model was marketed as the tourer version of the somewhat sportier (4-1) CB550F2 that was on the market simultaneously.

Sure, I'm sorry I wasn't more specific in my introductory post. I have a 78 CB550K with stock sprocket set up, so front = 17 and rear = 37. I've performed a few performance mods on this bike over the years. Specifically speaking I've swapped out the 4 into 4 exhaust with a 4 into 1, I swapped out the stock cam with a 650 cam and I've recently taken the head to my machinist for a mild port job. I'd like to do one last thing during my current rebuild to ensure that I have little more low end power, quicker off the line, etc, and that's to swap out the stock sprockets and go two teeth up in the back and maybe one tooth down in the front. Two up in the back may be enough, I don't know. I'll see, if I can find it!

[rusty_tank]

Sprocket Specialists will have everything you need.

Thank you very much for this lead. I hope to give em a call on Monday 

[scunny]

hope you aren't planning going out of town with the new gearing. 

[rusty_tank]

hope you aren't planning going out of town with the new gearing. 

Tell me more scunny. I'm still learning about this mod and would like to get as much info about it as possible...or at least get different perspectives.

[mrfish2]

I dropped a tooth in the front on my 550 and there is a noticeable difference in taking off. With the 16 tooth front sprocket it turns about 500 rpms higher than a 17 tooth at cruising speeds. In other words, with the 17 tooth at about 70 mph in 5th gear my bike was turning about 6500 rpms, and with the 16 tooth at the same speed it'll turn at 7000 rpms (if I'm remembering all that correctly). Also knocked my top speed from 110 to 105, as indicated by the stock speedo, but there's no telling how accurate that is haha.

[rusty_tank]

I dropped a tooth in the front on my 550 and there is a noticeable difference in taking off. With the 16 tooth front sprocket it turns about 500 rpms higher than a 17 tooth at cruising speeds. In other words, with the 17 tooth at about 70 mph in 5th gear my bike was turning about 6500 rpms, and with the 16 tooth at the same speed it'll turn at 7000 rpms (if I'm remembering all that correctly). Also knocked my top speed from 110 to 105, as indicated by the stock speedo, but there's no telling how accurate that is haha.

Thanks mrfish2 for a report on your personal experience. That's awesome to hear. So you didn't go up any teeth in the back huh?

[mrfish2]

Nope, kept the 37 in the back. I've considered going to a 41 in the rear, but then it would rev too high to cruise along the highway and I'm not ready to make my bike a strict canyon carver.

The chart I've attached is a real good visual on gearing ratios with different sprocket sizes. You can see that the stock 550 setup nets a 2.18 ratio, and my setup with the 16 tooth in the front gives me a 2.31.

[Retro Rocket]

What do you want, faster off the line or less revs at highway speeds...?

I want, "faster off the line". It's my understanding this is a fairly common mod, no?

Just asking, you'd be surprised how many people get the gearing wrong...your fuel economy will suffer by lowering the gearing as the bike will rev higher on the highway as previously mentioned....

[rusty_tank]

Nope, kept the 37 in the back. I've considered going to a 41 in the rear, but then it would rev too high to cruise along the highway and I'm not ready to make my bike a strict canyon carver.

The chart I've attached is a real good visual on gearing ratios with different sprocket sizes. You can see that the stock 550 setup nets a 2.18 ratio, and my setup with the 16 tooth in the front gives me a 2.31.

That is fcking rad dude. Thank you so much for sharing that ratio chart. So your experience with going down one tooth in the front, it sounds like, has been positive in that there's a noticeable difference off the line, aka from stop to go, but your still able to travel on the highway/freeway without any issues other than MAYBE your top speed being 105 and a bit of fuel economy suffrage throughout. Correct?
Btw, I checked out Sprocket Specialists website, found exactly what I need. Those guys are the business. Thanks again for the recommendation.

What do you want, faster off the line or less revs at highway speeds...?

I want, "faster off the line". It's my understanding this is a fairly common mod, no?

Just asking, you'd be surprised how many people get the gearing wrong...your fuel economy will suffer by lowering the gearing as the bike will rev higher on the highway as previously mentioned....

About the fuel economy, yea I figured as much, makes sense. I think I'll try going down one tooth as mrfish2's done and see how it goes from there.
And no I wouldn't be surprised at all how many people get it wrong. I had to ask my buddy three times whether it was up or down a tooth in the front or rear or both? The info just wasn't stickin! It's finally stuck

Thanks Retro Rocket

[rusty_tank]

  I thought of a couple questions.

1. What's the difference in going down a tooth in the front vs. going up a tooth in the back? If a bike owner was to only change one sprocket is there a benefit to changing the front sprocket over the rear sprocket or vice versa?

2. If you go down 1 tooth in the front wouldn't going up 1 or 2 in the rear compensate to some degree?

If I'm being a complete fckin idiot let me know

[Retro Rocket]

I thought of a couple questions.

1. What's the difference in going down a tooth in the front vs. going up a tooth in the back? If a bike owner was to only change one sprocket is there a benefit to changing the front sprocket over the rear sprocket or vice versa?

2. If you go down 1 tooth in the front wouldn't going up 1 or 2 in the rear compensate to some degree?

If I'm being a complete fckin idiot let me know

This is where it gets tricky, going down one tooth on the front lowers the gearing, so does going UP teeth on the rear, so if you went down one tooth on the front and up a couple of teeth on the rear you've drastically lowered the gearing by lowering the gearing at both ends, if you went down one tooth at the front and down a couple at the rear you'll end up with close to the same gearing you started out with... To lower gearing go down teeth at the front or up teeth at the rear {not both} , to raise the gearing go up teeth at the front and down teeth at the rear Again {not both} ...  Confused yet....

[Scott S]

 I've got a used but good 39 tooth rear sprocket I'd sell you cheap. It's aluminum, too. Came with a bunch of parts.

[rusty_tank]

I thought of a couple questions.

1. What's the difference in going down a tooth in the front vs. going up a tooth in the back? If a bike owner was to only change one sprocket is there a benefit to changing the front sprocket over the rear sprocket or vice versa?

2. If you go down 1 tooth in the front wouldn't going up 1 or 2 in the rear compensate to some degree?

If I'm being a complete fckin idiot let me know

This is where it gets tricky, going down one tooth on the front lowers the gearing, so does going UP teeth on the rear, so if you went down one tooth on the front and up a couple of teeth on the rear you've drastically lowered the gearing by lowering the gearing at both ends, if you went down one tooth at the front and down a couple at the rear you'll end up with close to the same gearing you started out with... To lower gearing go down teeth at the front or up teeth at the rear {not both} , to raise the gearing go up teeth at the front and down teeth at the rear Again {not both} ...  Confused yet....

Retro Rocket, thanks for this explanation. That really does help a lot...with making me more confused
JK, I get it...I think

[mrfish2]

Nope, kept the 37 in the back. I've considered going to a 41 in the rear, but then it would rev too high to cruise along the highway and I'm not ready to make my bike a strict canyon carver.

The chart I've attached is a real good visual on gearing ratios with different sprocket sizes. You can see that the stock 550 setup nets a 2.18 ratio, and my setup with the 16 tooth in the front gives me a 2.31.

That is fcking rad dude. Thank you so much for sharing that ratio chart. So your experience with going down one tooth in the front, it sounds like, has been positive in that there's a noticeable difference off the line, aka from stop to go, but your still able to travel on the highway/freeway without any issues other than MAYBE your top speed being 105 and a bit of fuel economy suffrage throughout. Correct?
Btw, I checked out Sprocket Specialists website, found exactly what I need. Those guys are the business. Thanks again for the recommendation.

Correct, it makes my bike rev a little higher at cruising speeds and DOES hurt the gas mileage a bit because of the highet revs. I only average around 31 mpg, but I'm also running a MotoGP Werks exhaust and a 115 main jet.

Look at the chart to understand Retro's explanation. Stock gearing is 2.18, one tooth down in the front makes it 2.31, and stock 17 in the front and 2 teeth up in the back gives you 2.29.

[rusty_tank]

Nope, kept the 37 in the back. I've considered going to a 41 in the rear, but then it would rev too high to cruise along the highway and I'm not ready to make my bike a strict canyon carver.

The chart I've attached is a real good visual on gearing ratios with different sprocket sizes. You can see that the stock 550 setup nets a 2.18 ratio, and my setup with the 16 tooth in the front gives me a 2.31.

That is fcking rad dude. Thank you so much for sharing that ratio chart. So your experience with going down one tooth in the front, it sounds like, has been positive in that there's a noticeable difference off the line, aka from stop to go, but your still able to travel on the highway/freeway without any issues other than MAYBE your top speed being 105 and a bit of fuel economy suffrage throughout. Correct?
Btw, I checked out Sprocket Specialists website, found exactly what I need. Those guys are the business. Thanks again for the recommendation.

Correct, it makes my bike rev a little higher at cruising speeds and DOES hurt the gas mileage a bit because of the highet revs. I only average around 31 mpg, but I'm also running a MotoGP Werks exhaust and a 115 main jet.

Look at the chart to understand Retro's explanation. Stock gearing is 2.18, one tooth down in the front makes it 2.31, and stock 17 in the front and 2 teeth up in the back gives you 2.29.

I'm mostly kidding. I understand Retro's post, pretty straight forward.
What I don't understand is, just what are those ratios referring to? What do the ratios represent?

I've just purchased a 16 tooth front sprocket for my CB550. Very excited. Thanks for your help everyone, this has helped a ton.

[seanbarney41]

ratio's are countershaft rotations/wheel rotations

[SohRon]

 I was contemplating the 16 tooth front sprocket, but Two Tired pointed out that doing that would put greater strain on the chain due to the smaller radius encountered and so I went for the larger rear sprocket instead. Easier on both chain and sprocket. Just FYI.

[rusty_tank]

I was contemplating the 16 tooth front sprocket, but Two Tired pointed out that doing that would put greater strain on the chain due to the smaller radius encountered and so I went for the larger rear sprocket instead. Easier on both chain and sprocket. Just FYI.

Thanks for your two cents SohRon. So how's your experience been with the larger rear sprocket, positive? About the same as what mrfish2 has reported regarding his front sprocket swap? Or different?

[rusty_tank]

I was contemplating the 16 tooth front sprocket, but Two Tired pointed out that doing that would put greater strain on the chain due to the smaller radius encountered and so I went for the larger rear sprocket instead. Easier on both chain and sprocket. Just FYI.

I know that what your suggesting is a concern, but not for a bike of this displacement and this little hp. I think it can become an issue when you have a significantly larger motor, like a 1000.

[Powderman]

I've never heard that going one tooth smaller would put excessive strain on the chain. Anyone else had this actually happen to them? The difference in circumference is not that drastic. I'm just not buying the theory. The chain can go a lot tighter radius than the size of the sprocket.