Need Gearing Advice

If it's broken or just needs tweaked

Moderators: Volker_P, tidd650

FordMan
Posts: 130
Joined: Fri Jul 18, 2014 10:20 pm
Location: Southern Minnesota

Need Gearing Advice

Postby FordMan » Sun Aug 03, 2014 10:12 pm

Hey, folks.
After getting my bike temporarily customized to finish out the riding season, I have experienced a few things i am not fond of, as in im not happy with the RPM im running while running down the highway.

My tach gauge has a bent needle so it never drops to 0, but i think its still fairly accurate, @ 70mph im running about 6k, i would like to get this to drop a fair amount since it will see alot of hwy miles at about 70 mph.

I am not to familiar with gearing changes, but i know smaller rear would help get me where i would like to be, but should i go bigger drive sprocket as well? I would like to be around 5k @ 70, but i have no idea what sprockets will get me there.

On my ride today, i walked all over my buddies 2011 shadow, up to 70. haha he was suprised it was that quick, and it would be nice to get a good balance between not losing all that quickness, and not revvin so hard @ 70.

Also i plan on replacing the chain with a new o-ring chain when i re gear, not only because im losing o-rings on the chain i have but i know its not good to use an old chain on new gears. Any chain brand recommendations, was think SK or DiD.

Any of your advice would be amazing.
"Vintage Revolution"
https://www.youtube.com/channel/UCOrn_h ... DZhOPmH81w
Current:
1979 Honda CB650 (HardTail Build)
1983 Suzuki GS850L (Fix and Minor Restore)
Old:
1989 Suzuki Katana 600
1978 Honda CB400T "Hawk"
1983 Honda VF750

MEHall
Posts: 403
Joined: Mon Nov 15, 2010 8:25 am
Location: Sweden

Re: Need Gearing Advice

Postby MEHall » Mon Aug 04, 2014 5:56 am

Actually the engine needs the revs to get the effect where it's needed. But if you really feel the need to alter the gearing one teeth less in the rear sprocket may suffice! :wink:




8)
Riding bikes? I ride where ever i want and whenever i want. :wink:

Online manual: http://cosky0.tripod.com/

Mainerider
Posts: 332
Joined: Thu Sep 02, 2010 8:45 pm

Re: Need Gearing Advice

Postby Mainerider » Mon Aug 04, 2014 6:28 am

http://www.gearingcommander.com

This site explains how gearing works and it also has a gearing calculator where you can plug your own bike's current gearing in and you can then substitute gearing combinations to see how it affects your particular bike. A very handy website...

Also keep in mind that clearance can be an issue when increasing the countershaft drive sprocket size; some bikes don't have the space to accommodate the increased diameter.

Regarding chains, we can only surmise what model and year your bike is; you didn't give that info. Regardless, any decent quality chain will do; these bikes in general are not high-performance sport bikes that need extremely high tensile strength chains.
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cb650
Posts: 2959
Joined: Fri Mar 03, 2006 7:20 am
Location: Denver CO USA
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Re: Need Gearing Advice

Postby cb650 » Mon Aug 04, 2014 8:26 am

FYI 1 front is about equal to 3 rear. What bike? sounds like my 81 standard. I would go up 1 front and see if you like it.
Did you clean the tank out?!?!?!?!

FordMan
Posts: 130
Joined: Fri Jul 18, 2014 10:20 pm
Location: Southern Minnesota

Re: Need Gearing Advice

Postby FordMan » Mon Aug 04, 2014 9:44 am

Sorry it's a 1979 650 the standard one I believe.
So is sustaining 6k rpm for a period of time normal, I just don't want to hurt the engine. I try to vary my speed often, but it just seems like a bad idea to keep the revs that high. But I'm no expert lol
"Vintage Revolution"
https://www.youtube.com/channel/UCOrn_h ... DZhOPmH81w
Current:
1979 Honda CB650 (HardTail Build)
1983 Suzuki GS850L (Fix and Minor Restore)
Old:
1989 Suzuki Katana 600
1978 Honda CB400T "Hawk"
1983 Honda VF750

cb650
Posts: 2959
Joined: Fri Mar 03, 2006 7:20 am
Location: Denver CO USA
Contact:

Re: Need Gearing Advice

Postby cb650 » Mon Aug 04, 2014 5:02 pm

79 had only one model. I always thought it was excessive rpm's too. first think I ever changed was the front sprocket.
Did you clean the tank out?!?!?!?!

FordMan
Posts: 130
Joined: Fri Jul 18, 2014 10:20 pm
Location: Southern Minnesota

Re: Need Gearing Advice

Postby FordMan » Mon Aug 04, 2014 10:46 pm

cb650 wrote:79 had only one model. I always thought it was excessive rpm's too. first think I ever changed was the front sprocket.


What did u step up to? I havent even researched what the front gear is, when i removed the rear to swap out the old tire, i thought i saw 41 stamped in the rear.
soon as i get a chance i will go bigger on the drive, get a new rear gear, same size, and a new o-ring chain
"Vintage Revolution"
https://www.youtube.com/channel/UCOrn_h ... DZhOPmH81w
Current:
1979 Honda CB650 (HardTail Build)
1983 Suzuki GS850L (Fix and Minor Restore)
Old:
1989 Suzuki Katana 600
1978 Honda CB400T "Hawk"
1983 Honda VF750

cb650
Posts: 2959
Joined: Fri Mar 03, 2006 7:20 am
Location: Denver CO USA
Contact:

Re: Need Gearing Advice

Postby cb650 » Tue Aug 05, 2014 8:02 am

I went up to a 18 from a 17. I dont know off hand what your is stock. On some bikes the 18 needs to have the inner guard (if its still there) moved around.
Did you clean the tank out?!?!?!?!

MiGhost
Posts: 379
Joined: Tue Jun 07, 2011 2:30 am
Location: South Central Mitten

Re: Need Gearing Advice

Postby MiGhost » Thu Aug 07, 2014 1:31 am

79-81 was 16\39 stock.
82 was 17\38 stock.

You can change to the 17\38 to get a 69.3mph @ 5000 rpm w/130-90-16.
Compared to 16\39 to get 69.2mph @ 5440rpm w/130-90-16.
~ Ghost

PD50 Carb Info
82 CB650SC Brake Caliper Info

Stable
Wayward Son:1980 CB650C, RestoMod Period Custom Touring
Bad Moon: 1983 XJ750MK Midnight Maxim, Full Dress Tour Deluxe w/ X-1 Fairing
Nemesis: 1983 XJ750K Maxim, Old School style chopper

MiGhost
Posts: 379
Joined: Tue Jun 07, 2011 2:30 am
Location: South Central Mitten

Re: Need Gearing Advice

Postby MiGhost » Thu Aug 07, 2014 1:32 am

cb650 wrote:I went up to a 18 from a 17. I dont know off hand what your is stock. On some bikes the 18 needs to have the inner guard (if its still there) moved around.


Where did you find the 18 front sprocket?

18\38 would give 70.5mph @ 4800 rpm
~ Ghost

PD50 Carb Info
82 CB650SC Brake Caliper Info

Stable
Wayward Son:1980 CB650C, RestoMod Period Custom Touring
Bad Moon: 1983 XJ750MK Midnight Maxim, Full Dress Tour Deluxe w/ X-1 Fairing
Nemesis: 1983 XJ750K Maxim, Old School style chopper

cb650
Posts: 2959
Joined: Fri Mar 03, 2006 7:20 am
Location: Denver CO USA
Contact:

Re: Need Gearing Advice

Postby cb650 » Thu Aug 07, 2014 6:09 am

Just bought on off ebay DK has them also. they need to be narrowed down a little. And for you gearing chart isnt there diff gears for the custom/nitehawk vs the standards? Seems to me the standards always had the 16 and the customs had the 17. All my customs have. You can find a 37 rear also.
Did you clean the tank out?!?!?!?!

MiGhost
Posts: 379
Joined: Tue Jun 07, 2011 2:30 am
Location: South Central Mitten

Re: Need Gearing Advice

Postby MiGhost » Thu Aug 07, 2014 12:16 pm

cb650 wrote:Just bought on off ebay DK has them also. they need to be narrowed down a little. And for you gearing chart isnt there diff gears for the custom/nitehawk vs the standards? Seems to me the standards always had the 16 and the customs had the 17. All my customs have. You can find a 37 rear also.


I stand corrected! Thats what I get for looking at the wrong notes!
79-81 Standard 16\40
82 Standard 17\39
80-81 Custom 16\39
82 SC Nighthawk 17\38

The 17T front was a common upgrade.

37T rear available in aluminum through either JT Sprockets, or Sprocket Specialist

Another tidbit of info.
18T Front: Will need to be narrowed to fit.
23801-300-620 SPROCKET (18T)
71-76 CB750K (K1-K6)

18\37 70.1mph @ 4650rpm
I knew that 6th gear was hiding there somewhere!
~ Ghost

PD50 Carb Info
82 CB650SC Brake Caliper Info

Stable
Wayward Son:1980 CB650C, RestoMod Period Custom Touring
Bad Moon: 1983 XJ750MK Midnight Maxim, Full Dress Tour Deluxe w/ X-1 Fairing
Nemesis: 1983 XJ750K Maxim, Old School style chopper

FordMan
Posts: 130
Joined: Fri Jul 18, 2014 10:20 pm
Location: Southern Minnesota

Re: Need Gearing Advice

Postby FordMan » Thu Aug 07, 2014 8:58 pm

What exactly is done to "Narrow" the sprocket?
"Vintage Revolution"
https://www.youtube.com/channel/UCOrn_h ... DZhOPmH81w
Current:
1979 Honda CB650 (HardTail Build)
1983 Suzuki GS850L (Fix and Minor Restore)
Old:
1989 Suzuki Katana 600
1978 Honda CB400T "Hawk"
1983 Honda VF750

MiGhost
Posts: 379
Joined: Tue Jun 07, 2011 2:30 am
Location: South Central Mitten

Re: Need Gearing Advice

Postby MiGhost » Fri Aug 08, 2014 1:49 am

FordMan wrote:What exactly is done to "Narrow" the sprocket?

You will need to remove some of the thickness of the sprocket from the sides to match the thickness of the stock sprocket.. Either by sanding, or grinding.
~ Ghost

PD50 Carb Info
82 CB650SC Brake Caliper Info

Stable
Wayward Son:1980 CB650C, RestoMod Period Custom Touring
Bad Moon: 1983 XJ750MK Midnight Maxim, Full Dress Tour Deluxe w/ X-1 Fairing
Nemesis: 1983 XJ750K Maxim, Old School style chopper

cb650
Posts: 2959
Joined: Fri Mar 03, 2006 7:20 am
Location: Denver CO USA
Contact:

Re: Need Gearing Advice

Postby cb650 » Fri Aug 08, 2014 5:27 am

put mine in a lathe at work. mill would work also
Did you clean the tank out?!?!?!?!


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