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Discussion Starter · #1 ·
Hey all,

I'm hoping to give my CJ360T a bit more legs as I'm currently using it as a highway commuter and it's not uncommon for me to sit at 5-6K RPM in 5th gear for the duration of my 50 mile journey to/from work. I'd like to drop this down a bit to get better mileage but not kill the bike for around town kind of stuff.

Is this really as "simple" as switching out the front or rear sprocket? If so, is there a preference as to number of teeth or which (both?!) sprockets to change.

Thanks,
Matt
 

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Yep, it's just that simple.

That said, you can go to far and the engine will wind up working too hard to maintain highway speeds, and that's not good either. And sometimes, there won't be enough space in the front to go too large. Most bikes however, will accomodate a +1 up front.

Changes in the front are generally 3x ~ 4x as effective as changes on the rear. That is, a +1 on the front is equivalent to -3 ~ -4 on the rear. And to slow the motor down at highway road speeds, that's what you'll want to do - add one tooth to the front or drop 2 ~ 3 teeth from the rear.

Fronts are usually cheaper than rears, too.

And finally, there's the aspect of replacing both sprockets and chain all at the same time. Worn chains on new sprockets will quickly wear the new sprockets.

Good luck with it.

Kirk
 

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Sonreir said:
Hey all,

I'm hoping to give my CJ360T a bit more legs as I'm currently using it as a highway commuter and it's not uncommon for me to sit at 5-6K RPM in 5th gear for the duration of my 50 mile journey to/from work. I'd like to drop this down a bit to get better mileage but not kill the bike for around town kind of stuff.

Is this really as "simple" as switching out the front or rear sprocket? If so, is there a preference as to number of teeth or which (both?!) sprockets to change.

Thanks,
Matt
Thanks for asking the question.

kirkn said:
Yep, it's just that simple.

That said, you can go to far and the engine will wind up working too hard to maintain highway speeds, and that's not good either. And sometimes, there won't be enough space in the front to go too large. Most bikes however, will accomodate a +1 up front.

Changes in the front are generally 3x ~ 4x as effective as changes on the rear. That is, a +1 on the front is equivalent to -3 ~ -4 on the rear. And to slow the motor down at highway road speeds, that's what you'll want to do - add one tooth to the front or drop 2 ~ 3 teeth from the rear.

Fronts are usually cheaper than rears, too.

And finally, there's the aspect of replacing both sprockets and chain all at the same time. Worn chains on new sprockets will quickly wear the new sprockets.

Good luck with it.

Kirk
Thanks for answering! Looks like I'll be upsizing my front to a 17.
 

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Discussion Starter · #4 ·
Well... I managed to find an 18 tooth front sprocket, but Google is really letting me down for anything smaller than a 33 tooth on the rear (which I already have).
Anyone have a source for something like this?
 

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What I remember of the 360 I had that the bike began to feel really happy from 6000 rpm on... :?
that is 2/3 of its RPM range.
If your bike is not happy at that rpm, maybe try 7000 rpm? :lol: :lol:
 

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Sonreir said:
The bike is plenty happy! Sounds and runs great.
I just want to see what I can do about keeping the fuel bill down as I'm going to be racking on the miles.
Two significant contributors: aerodynamics and weight.

So, keep your head low, and skip breakfast...
 

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A 360 will take up to an 18 tooth front sprocket.
I am running mine geared for 6000 at 58 mph & it sounds very happy in the 55 - 75 mph cruise range.
I always thought it seemed a bit tall geared at 5500 rpm at 60, but my stock carbs were junk too.
I will probably raise my gearing somewhat yet. Right now my mutant CB360 has 18/46 gearing.
 

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sprocket specialists may be able to help you out, but beware, I got a "36 tooth" sprocket from them with 38 teeth. it was even stamped 36t. that and the recessed groove for the cush drive pins was the wrong diameter, I had to do a little artful grinding to make it work.
 

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For the past ten years, I had been running my Kawasaki with +2 teeth up front to remove engine resonation at highway cruising speed. It would vibrate at about 57mph annoyingly. Doing the sprocket conversion made it resonate at about 67mph instead.

However, my top speed was lower (about right at 100mph) and could only be reached in 4th gear. 5th gear was only good for about 92mph according to my GPS. When I changed my rear tire last autumn I decided to put the factory sprocket back in and have been happier with the extra get up and go around town. I just cruise at higher RPM now, maybe even 4th gear because my engine smooths out when you power through the vibration.
 
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