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Offline DJ

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Re-Gear 39 tooth out back with 16 tooth up front
« on: June 10, 2019, 03:40:45 AM »
Just wanted to add my .2 cents regarding re-gearing the 500x.

When I got my bike I rode it home 160 miles on the highway from Portland to Seattle.  I was blown away that it was screaming at 6,000 rpm at 70mph on the highway. Not in a good way.  It only redlines at 9,000.  Why would a manufacturer do that is beyond me.

I struggled with the idea for a few days. People saying it wasnt bad, it doesn't hurt the engine turning that fast for so long blahs blahs whatever.  Ride around in first gear at 6,000 rpm without a helmet so you can hear what it sounds like.

First I just did the 39 tooth in the rear, didn't change the rpms that much. Maybe 300rpm or so.  Put on the 16 tooth front and found what I was looking for. 

The bike is better all around now however, the speedometer is off by quite a bit.  At 62mph indicated on the guage it now turns at 5,000 rpm, a full 1,000 less rpm than before.  My GPS told me is was doing 72 while the bike said 62. Whatever, i can do math.  Obviously at a lower speed the difference is less.  It is more enjoyable on the highway as a result.  Still pulls just fine for passing. Dropping a gear is easy if need be. 

I've done over 100 miles now offroad with the new gears and TKC 80s. Actually like it better off road also. Before first and second were too short and third was too tall for most fire roads.  Now I cruse in 2nd, just perfect for fire roads 20-30 mph. 
Low speed is fine, I've not noticed much of a difference. Keep in mind when re-gearing, the ratios are affected more as the speed increases.  Low speed is marginally affected but as the speed increases the difference is more noticeable. 

I went up a few spots a buddy on an xt250 had to take a second run at. Plus, this isn't a slow speed technical bike anyways. Still works fine in the dirt.

Just wanted to throw yet another opinion out there.  If your on the fence, just do it. You won't regret it.

Offline Ceddy17

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #1 on: June 10, 2019, 09:39:59 AM »
Just asking to understand: did you change both sprockets - a 16 and a 39?
Or did you change only the front to a 16 and put the 41 back on?
I am aiming to do a sprocket change myself so I want to be sure about the effect it could have.
Maybe the changing of both sprockets is too much for the engine?
Thanks,
Ed.
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Offline motorboy

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #2 on: June 10, 2019, 02:34:27 PM »
 :139:Sounds a bit odd my old and new X both geared the same turn 5500rpm at 70mph :084:   also a speed healer will fix the speedo error easy
« Last Edit: June 10, 2019, 02:36:40 PM by motorboy »
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Offline DJ

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #3 on: June 10, 2019, 03:21:05 PM »
Ceddy I changed the rear first, that reduced rpm by about 300 at 70mph. Then I changed the front also.  Front is 16 and rear is 39. 
Only regret is not using a GPS before the change. I dont know how fast I was actually going before, just what the bike told me and they are always off it seems.

Recap: stock gearing at 75mph on the highway was 6,000 rpm. (MY APOLOGIES, I SAID 70 IN THE FIRST POST). 
With 16 tooth front AND 39 tooth rear it's at 5,000 rpm with a GPS indicated 72 mph while speedo on the bike shows 62 mph. 

Offline JMo

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #4 on: June 10, 2019, 04:04:17 PM »
*Originally Posted by DJ [+]
It only redlines at 9,000.  Why would a manufacturer do that is beyond me.

To maximise the [modest] power characteristics throughout the majority of the rev range... and give a usefully low first gear.

However, as you've found, for you own personal use, you prefer taller gearing for extended highway use - and that's great - fortunately there are readily available [and affordable] alternative sprockets available to tailor your preference.

for info though (for anyone else reading), 16/39 would mean you're in danger of having to seriously slip the clutch in really technical terrain... fortunately the CB has great low-end torque characteristics which helps to mitigate that - although I certainly wouldn't want a taller first gear on a 200Kg bike in some demanding off-road conditions.

Jx

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Offline racer

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #5 on: June 10, 2019, 06:48:55 PM »
I just ordered a JT 16 tooth sprocket and I think it will make the bike gearing where it needs be.  As far as gearing the bike up, off road, taller gearing will make you a better rider.  Remember,  :211: when you put your feet down, you've essentially decided to quit riding the bike.  Racer

Offline JMo

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #6 on: June 10, 2019, 06:55:43 PM »
*Originally Posted by racer [+]
I just ordered a JT 16 tooth sprocket and I think it will make the bike gearing where it needs be.  As far as gearing the bike up, off road, taller gearing will make you a better rider.  Remember,  :211: when you put your feet down, you've essentially decided to quit riding the bike.  Racer

You have low[er] gears so you can keep moving at a snails pace without putting your feet down.

Like a trials rider does.

All having [too] tall gears will do is cause you to slip the clutch and potentially stall, or else wheelspin as you try to rev the engine high enough to make enough torque to not stall/burn out the clutch.

Jx
« Last Edit: June 10, 2019, 06:57:09 PM by JMo »
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Offline Jonathan

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #7 on: June 10, 2019, 07:34:27 PM »
*Originally Posted by DJ [+]
Just wanted to add my .2 cents regarding re-gearing the 500x.

When I got my bike I rode it home 160 miles on the highway from Portland to Seattle.  I was blown away that it was screaming at 6,000 rpm at 70mph on the highway. Not in a good way.  It only redlines at 9,000.  Why would a manufacturer do that is beyond me.

I struggled with the idea for a few days. People saying it wasnt bad, it doesn't hurt the engine turning that fast for so long blahs blahs whatever.  Ride around in first gear at 6,000 rpm without a helmet so you can hear what it sounds like.

First I just did the 39 tooth in the rear, didn't change the rpms that much. Maybe 300rpm or so.  Put on the 16 tooth front and found what I was looking for. 

The bike is better all around now however, the speedometer is off by quite a bit.  At 62mph indicated on the guage it now turns at 5,000 rpm, a full 1,000 less rpm than before.  My GPS told me is was doing 72 while the bike said 62. Whatever, i can do math.  Obviously at a lower speed the difference is less.  It is more enjoyable on the highway as a result.  Still pulls just fine for passing. Dropping a gear is easy if need be. 

I've done over 100 miles now offroad with the new gears and TKC 80s. Actually like it better off road also. Before first and second were too short and third was too tall for most fire roads.  Now I cruse in 2nd, just perfect for fire roads 20-30 mph. 
Low speed is fine, I've not noticed much of a difference. Keep in mind when re-gearing, the ratios are affected more as the speed increases.  Low speed is marginally affected but as the speed increases the difference is more noticeable. 

I went up a few spots a buddy on an xt250 had to take a second run at. Plus, this isn't a slow speed technical bike anyways. Still works fine in the dirt.

Just wanted to throw yet another opinion out there.  If your on the fence, just do it. You won't regret it.




QED...

Offline SilverCycle

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #8 on: June 10, 2019, 10:24:06 PM »
I don't really understand the speedo being out after final drive changes, at least, not compared with automobiles I've worked on (worked as developer). If the bike has ABS rotation sensors on each wheel, surely the obvious speedo input is an average of the wheels, allowing for tyre sizes and maybe wheelspin/lockup? That's how a modern car does it. Why would Honda go to the expense of a separate sensor on the other side of the final drive, or a gear selection sensor?

And using the wheel sensor would only be affected by tyre size.

Offline JMo

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Re: Re-Gear 39 tooth out back with 16 tooth up front
« Reply #9 on: June 10, 2019, 10:27:39 PM »
*Originally Posted by SilverCycle [+]
I don't really understand the speedo being out after final drive changes, at least, not compared with automobiles I've worked on (worked as developer). If the bike has ABS rotation sensors on each wheel, surely the obvious speedo input is an average of the wheels, allowing for tyre sizes and maybe wheelspin/lockup? That's how a modern car does it. Why would Honda go to the expense of a separate sensor on the other side of the final drive, or a gear selection sensor?

And using the wheel sensor would only be affected by tyre size.

Hi SilverCycle - Not all CB500Xs have ABS. The speedo sensor works off the gearbox (output shaft) - hence why gearing (and tyre size) changes affect the overall reading.

As someone mentioned earlier, if the % change is significant, you can always fit a 'speedo healer' device.

Jx
It's not a unicorn as such, just a little mule with a bump on it's head... www.CB500Xadventure.com

 


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