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Author Topic: Hush's 650 front sprocket experiment  (Read 3201 times)

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Offline Hush

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Hush's 650 front sprocket experiment
« on: March 16, 2011, 08:20:31 PM »
I've been tossing this around for quite a while, even got to the stage where I was going to sell the old girl and get something more user friendly on the open road.
Anyhow after long discussions with my mate at work who has a shed full of old Indian bikes I have decided to up the front sprocket from a 16 to a 17.
He said that when they bore the Indian out from 500cc to 600cc they go up a tooth and from 600cc to 700cc two teeth but those old engines lug like crazy diesels. :D
This may not be earth shattering news (actually we could do with a little less of the earth shattering about now) but it's something that has bugged me and put me off riding my bike many times.
I believe the Police had these bikes set-up for quick short sprint pursuits and not long lazy days on the highway.
I saw that one of our forum members (thanks MJSTONE for the tip) purchased a new sprocket from JT Sprockets via Ebay so had a look around their site and they produce a 17 tooth one for the 79 CB650.
With our horrible exchange rate the reasonably priced US$17 cog converts to NZ$24.59 and once you add P&P it's NZ$68.39 but if it helps me fall in love with Blondie again it will be worth it. ;)
Not sure how long I gotta wait for delivery but this could be worth waiting for.
« Last Edit: March 16, 2011, 09:11:23 PM by Hush »
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline scunny

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Re: Hush's 650 front sprocket experiment
« Reply #1 on: March 16, 2011, 08:28:30 PM »
will wait on your report Rick. I find mine a bit "buzzy" on the open road.
that's with the 15/39 combo.
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Offline Hush

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Re: Hush's 650 front sprocket experiment
« Reply #2 on: March 16, 2011, 09:16:24 PM »
Yeah "buzzy" is how I'd describe it Larry, it feel like it needs a 6th gear which my toe searches endlessly for but never finds. Sometimes I pull right over and start off in first again because it feels like I can't get past 3rd ot 4th gear so I can count them as I shift!
I need what Jaffa's GSX400 has, a gear selector indicator panel, and she has 6 gears too lucky bag! :D

Hey Larry I just had an idea since you are running a 15 tooth on the front, if this 17T cures my problem I'm sending you my old 16 tooth as it will definitely make a difference to your bike, see I never forget a favour mate and I'm still in your debt for that gas tank tap you sent me last year. ;)
« Last Edit: March 16, 2011, 09:21:10 PM by Hush »
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline singedebile

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Re: Hush's 650 front sprocket experiment
« Reply #3 on: March 16, 2011, 09:45:13 PM »
Quote from: Hush on March 16, 2011, 09:16:24 PM
Yeah "buzzy" is how I'd describe it Larry, it feel like it needs a 6th gear which my toe searches endlessly for but never finds. Sometimes I pull right over and start off in first again because it feels like I can't get past 3rd ot 4th gear so I can count them as I shift!
I need what Jaffa's GSX400 has, a gear selector indicator panel, and she has 6 gears too lucky bag! :D

Hey Larry I just had an idea since you are running a 15 tooth on the front, if this 17T cures my problem I'm sending you my old 16 tooth as it will definitely make a difference to your bike, see I never forget a favour mate and I'm still in your debt for that gas tank tap you sent me last year. ;)

I think it has to do with my training from driving cars stick shift...  the engines just dont mind being shifted early for better gas mileage, and with my 550 I am always looking for another highway gear.. this is likely made worse by my 16inch wheel and i have yet to count the teeth to see if there was an attempt made to compensate ,
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Offline Gordon

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Re: Hush's 650 front sprocket experiment
« Reply #4 on: March 16, 2011, 09:51:36 PM »
Quote from: singedebile on March 16, 2011, 09:45:13 PM
Quote from: Hush on March 16, 2011, 09:16:24 PM
Yeah "buzzy" is how I'd describe it Larry, it feel like it needs a 6th gear which my toe searches endlessly for but never finds. Sometimes I pull right over and start off in first again because it feels like I can't get past 3rd ot 4th gear so I can count them as I shift!
I need what Jaffa's GSX400 has, a gear selector indicator panel, and she has 6 gears too lucky bag! :D

Hey Larry I just had an idea since you are running a 15 tooth on the front, if this 17T cures my problem I'm sending you my old 16 tooth as it will definitely make a difference to your bike, see I never forget a favour mate and I'm still in your debt for that gas tank tap you sent me last year. ;)

I think it has to do with my training from driving cars stick shift...  the engines just dont mind being shifted early for better gas mileage, and with my 550 I am always looking for another highway gear.. this is likely made worse by my 16inch wheel and i have yet to count the teeth to see if there was an attempt made to compensate ,

The tires made for 16" rims typically have taller sidewalls, so the overall difference in diameter compared to an 18" rim and tire combo is usually little if any. 
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Offline Pinhead

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Re: Hush's 650 front sprocket experiment
« Reply #5 on: March 16, 2011, 09:52:37 PM »
I think you'll be happy you did it. I've been running a 17t front and don't plan on going back!
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Offline Hush

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Re: Hush's 650 front sprocket experiment
« Reply #6 on: March 17, 2011, 02:04:17 AM »
That sounds encouraging Pinhead. :)
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline cb650

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Re: Hush's 650 front sprocket experiment
« Reply #7 on: March 17, 2011, 03:35:09 AM »
I always change the front at least.  On my current bike changed rear also.  Little over geared for the mts but out on the flat it's great.    Can always go down a gear when need be.
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Offline RickB

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Re: Hush's 650 front sprocket experiment
« Reply #8 on: March 17, 2011, 03:40:55 AM »
So what's the thinking on this guys? I'm a novice so sorry for the noob question. More teeth better top end? Or better take off?
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Offline Retro Rocket

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Re: Hush's 650 front sprocket experiment
« Reply #9 on: March 17, 2011, 03:53:13 AM »
Quote from: RickB on March 17, 2011, 03:40:55 AM
So what's the thinking on this guys? I'm a novice so sorry for the noob question. More teeth better top end? Or better take off?

More teeth on the back or less teeth on the front equals lower gearing which means more revs for any given speed, less teeth on the back or more teeth on the front will raise gearing meaning less revs for the same speeds...

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Offline dave500

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Re: Hush's 650 front sprocket experiment
« Reply #10 on: March 17, 2011, 04:04:19 AM »
these things really hum on the highway,im not keen on extended 110 kay (65 mph) running either,i live in a hilly twisty area so i leave it stock,these engines also like a little bit of load so at flight rpms they seems to be spinning to hard,but the same revs under load like a hill and it feels better.
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Offline Hush

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Re: Hush's 650 front sprocket experiment
« Reply #11 on: March 17, 2011, 01:07:50 PM »
If you look at a trail bike Rick you will see a tiny front sprocket and a huge rear one, this gives them quick acceleration over short distances which is just what trail bikes need in rough ground.
Our big road bikes need a higher gearing so a bigger front sprocket will mean my 650 isn't revving like Hell when I should be cruising (which is the case now).
They also produce a 18 tooth front for the later model 650's but I think the spline is different and anyway I only want to go up one tooth at a time to see the effect.
I once destroyed my rear sprocket on my Suzuki T350 while on a trip and the only replacement I could get without waiting for one from Japan was a TS400 trail, my rear was a 36 tooth and the T400 was a 42 tooth, it just fitted under the chainguard.
I could pull wheel-stands in 1st 2nd and 3rd  ;D it made for an interesting trip home with me trying to keep the front wheel on the ground at every set of lights. :D
« Last Edit: March 17, 2011, 06:42:09 PM by Hush »
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline RickB

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Re: Hush's 650 front sprocket experiment
« Reply #12 on: March 17, 2011, 06:30:16 PM »
Thanks for the explanation guys. That's a funny story Hush, definitely don't wont to be doing that on your 650!
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Offline mjstone

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Re: Hush's 650 front sprocket experiment
« Reply #13 on: March 17, 2011, 07:12:03 PM »
Quote from: Hush on March 16, 2011, 08:20:31 PM
I saw that one of our forum members (thanks MJSTONE for the tip) purchased a new sprocket from JT Sprockets via Ebay so had a look around their site and they produce a 17 tooth one for the 79 CB650.

Glad I could help Hush.  Hope it works out well for you.

MJ
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Offline Hush

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Re: Hush's 650 front sprocket experiment
« Reply #14 on: March 27, 2011, 07:32:25 PM »
Love it love it, the engine seems to have relaxed with the extra tooth on the sprocket, it used to be 30mph=3000revs and 40mph=4000 revs but now there is a drop of exactly 1000 revs?
30mph now equals 2000 rpm and 40mph=3000 rpm, in fact I was hard pushed to get the bike to rev past 5000 rpm at all while riding.
No drop in power, smoother if anything.
Scunny are you sure you are running a 15T on the front?
Happy to send you my 16T as there is no way I would go back to it now, just curious to see if indeed you counted right. ;D
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

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Re: Hush's 650 front sprocket experiment
« Reply #15 on: March 27, 2011, 07:53:49 PM »
Hush It would depend on what police force the Highway patrol allways wanted top end. They would pick up the chase when the city and county started falling off because they wanted 1-2-3 gear speed and would set there sprockets up for that.
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Offline Hush

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Re: Hush's 650 front sprocket experiment
« Reply #16 on: March 27, 2011, 11:56:09 PM »
Yeah mine was geared for quick short street pursuits (wouldn't stand a chance against modern cars) so I'm altering for highway riding now.
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline mjstone

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Re: Hush's 650 front sprocket experiment
« Reply #17 on: March 28, 2011, 09:48:51 AM »
Glad to hear that it's working out for ya Hush. :)

MJ
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Offline wardenerd

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Re: Hush's 650 front sprocket experiment
« Reply #18 on: March 28, 2011, 10:15:08 AM »
my stock 1981 650C has in 5th gear a speed to revs as follows 50 MPH 3700 RPM.  60MPH 4600 his may be off by 100 or so RPM's from looking at the two guages.
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Offline Hush

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Re: Hush's 650 front sprocket experiment
« Reply #19 on: March 28, 2011, 12:45:21 PM »
Yes that looks about right Wardenerd.
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline wardenerd

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Re: Hush's 650 front sprocket experiment
« Reply #20 on: March 29, 2011, 05:02:32 AM »
If I was going to change it I would go for lower rpm at cruise speeds.  The bikes got plenty of get up and go. How much difference woul one tooth make?  2 teeth?
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Offline Hush

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Re: Hush's 650 front sprocket experiment
« Reply #21 on: March 29, 2011, 01:09:19 PM »
You would be suprised, I just couldn't take my bike home and park it up I was having way too much fun yesterday. ;D
The engine is much more relaxed at cruising speed yet the pick-up from lights and stop signs wasn't badly affected at all?
I'd love to try the 18 tooth CB650CS front sprocket but the inner profile of their sprockets is completely different to the early 650's.
Anyhow I'm sold on the 17T and that 16T can go to a better home, Scunny I'll need your address again. :D
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline cb650

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Re: Hush's 650 front sprocket experiment
« Reply #22 on: March 29, 2011, 02:09:51 PM »
I've ran a 18 on my 80.    All you have to watch is that the "gaurd" doesnt rub.
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Offline mjstone

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Re: Hush's 650 front sprocket experiment
« Reply #23 on: March 29, 2011, 04:44:48 PM »
What about dropping a tooth or two in the back, Hush?  Wouldn't that have the same affect?   Then you wouldn't have the clearance problem.

MJ
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Offline cb650

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Re: Hush's 650 front sprocket experiment
« Reply #24 on: March 29, 2011, 06:12:37 PM »
The rear doesnt effect it as much. And the smallest rear you you can get is 37 teeth.   
1 front will equal 3 rear.
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