Sprocket setups? What are you running?

If it's broken or just needs tweaked

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Nate
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Sprocket setups? What are you running?

Postby Nate » Mon Nov 13, 2006 12:50 am

I currently have the stock 16T Front and 40T Rear on my 1980 CB650. I am considering going to a 17T Front 39T Rear to give me a few less RPM's at highway cruising speeds. Anyone tried this setup or others?

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Volker_P
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Re: Sprocket setups? What are you running?

Postby Volker_P » Mon Nov 13, 2006 2:08 am

I have a 17/39 setup at my CB650C (RC05, stock 16/39), however as the rear wheel is smaller compared to the RC03 model (16" against 18") from rpm vs. speed reading this comes close to the original RC03 setup (quite exactly 5000rpm at 100km/h). You can live with this transmission ratio even with the 50hp engine as long as you ride mostly alone. As you report low rev problems in your other post, you may prefer to leave it as it is. Riding at load at low rpm may damage the main bearings, especially when your oil pump has already the tolerances of beyond 50000km or so. Also the 4th and 5th gearwheels may be affected.
The 17 front sprocket will fit, but it will require (minor) changes to the inner chain guard below the left side engine cover. I won't leave away this guard as it provides some protection of the oil pump against stones.

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Ibsen
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Postby Ibsen » Mon Nov 13, 2006 2:15 am

I'm running the stock set up on my 650, 16/40. I have just ordered a new chain and sprockets, and I choose to stay with the stock sizes.
One thing you should have in mind if you buy larger sprockets is the chain length if you are replacing it. A new standard 102 link chain could get tight, so it would be wise to buy one that is longer, 104 or 106, and if that is too much you can cut off the number of links required.

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Volker_P
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Re: Sprocket setups? What are you running?

Postby Volker_P » Mon Nov 13, 2006 2:31 am

Ibsen wrote:I'm running the stock set up on my 650, 16/40. I have just ordered a new chain and sprockets, and I choose to stay with the stock sizes.
One thing you should have in mind if you buy larger sprockets is the chain length if you are replacing it. A new standard 102 link chain could get tight, so it would be wise to buy one that is longer, 104 or 106, and if that is too much you can cut off the number of links required.

One front tooth more works with standard chain length, at least for the RC05 (I guess stock is 104 there). When you simultaneously cancel one rear tooth, it will even compensate to fit better. I think it was you that reported 5000rpm vs. 100km/h for RC03 some time ago? Even after my test with the 63hp camshaft, I also would not recommend to go below that, although I sometimes look for the next gear during a ride. :lol:

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Ibsen
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Postby Ibsen » Mon Nov 13, 2006 3:03 am

Yes, I do look for a next gear sometimes as well :lol: , but I do like that the engine is flexible even in 5th gear. That's the reason I choose the stock size.

The numbers are correct, so it might have been me who posted about the rpm at 100kph :)
The rpm variations with the different sprocket sizes can also be calculated:

http://www.xs4all.nl/~ator0437/gc/

http://www.sprocketspecialists.com/Spro ... izer2.aspx

Nate
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Postby Nate » Mon Nov 13, 2006 8:43 am

The reccomended chain link on the 80 is 104. I have the 17" rear rim. Maybe i'll just go with the 17T front and stick with the 40T Rear. A little bit of benifit without risking to much lag.

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Vatch
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Postby Vatch » Tue Nov 14, 2006 8:03 pm

The stock 16/40 works pretty well. Consider these bikes were orginally offered as light touring bike, although legal US speeds were lower then. As long as the bike is maitained she'll run 70-75mph on interstates all day with no problems. Your ass will give out before the engine will :lol: The buzz of the higher RPM's (should be around 6000-6500 or so at those speeds) takes a little to get used to depending on other bikes you've ridden, but you're still well below red line. Granted, you won't be able to see in your mirrors, so beward of Johnny Law from behind. :twisted:
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