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Offline macker

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Gearing for more speed
« on: September 01, 2019, 06:38:41 pm »
I am busy setting up a  Honda XR 400R for Dual-sport riding and currently the bike has plenty low down power and cruisers at around 90 km/h comfortably, but  after that starts revving too high  - what are the pro's / cons of going bigger on the front sprocket, or smaller at the back to get more top-end??  is one more pronounced than the other or is it much of a muchness.....
 

Offline Bundu

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Re: Gearing for more speed
« Reply #1 on: September 01, 2019, 06:42:14 pm »
take a look here https://sprocketcalculator.com/

you'll see that nothing is for free  ;D
 

Offline macker

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Re: Gearing for more speed
« Reply #2 on: September 01, 2019, 06:55:51 pm »
Thanks Bundu, handy site, 1 bigger in front gives a bigger top end differential than 2 smaller at the back, interesting.
As you say, never thought about having to change the chain as well.
 

Offline Bundu

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Re: Gearing for more speed
« Reply #3 on: September 01, 2019, 07:34:14 pm »
also remember that when you increase the top speed, you also stretch your 1st gear and increase your crawling speed for technical terrain
 

Offline 2StrokeDan

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Re: Gearing for more speed
« Reply #4 on: September 01, 2019, 07:39:53 pm »
Be careful of too tall gearing, as you may sit on open stretches with a carburettor butterfly too far open, and the engine lugging.

It is seldom that the standard gearing can be improved upon.
 
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Offline LouisXander

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Re: Gearing for more speed
« Reply #5 on: September 01, 2019, 08:35:58 pm »
Uncle Dan, by lugging you mean lile the carb runs out of feul for a second or 2?

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Offline dirtWarp

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Re: Gearing for more speed
« Reply #6 on: September 01, 2019, 08:51:21 pm »
Maybe not what you want to hear but I had the same issue with my xr400.

Ended up selling it for a 600 and never looked back.

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Re: Gearing for more speed
« Reply #7 on: September 01, 2019, 09:39:07 pm »
more speed = more wind resistance = more power needed.

Changing gearing will mean less revs at higher speed = less power available at higher speed.

Therefore it's possible to gear for more speed but not achieve it.

Hopefully a 400 has the extra power ....................

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Offline Bill the Bong

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Re: Gearing for more speed
« Reply #8 on: September 02, 2019, 10:39:08 am »
First get a hot cam and a pro circuit pipe or the like, otherwise you might not be able to pull the revs required.  Going faster is not simply a gearing equation.   I'd just go 1 tooth larger in front, that's a R300 experiment, see if the bike still has some reserve power.
 

Offline LouisXander

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Re: Gearing for more speed
« Reply #9 on: September 02, 2019, 10:52:09 am »
Bill just said it. Do that.

Just make sure your front does not devided into your rear by 3..... i.e: 15/45.

It'll drive you crazy.

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Offline macker

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Re: Gearing for more speed
« Reply #10 on: September 02, 2019, 12:33:36 pm »
Thanks for all the input. Reckon I'll go for one up on the front- as Bill says a R300 experiment and quick job to change back if needed.
 

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Re: Gearing for more speed
« Reply #11 on: September 02, 2019, 12:36:39 pm »
Be careful of too tall gearing, as you may sit on open stretches with a carburettor butterfly too far open, and the engine lugging.

It is seldom that the standard gearing can be improved upon.
except on the R1150GS which is way over geared at altitude 🙄
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Offline jaybiker

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Re: Gearing for more speed
« Reply #12 on: September 02, 2019, 12:41:19 pm »
Be careful of too tall gearing, as you may sit on open stretches with a carburettor butterfly too far open, and the engine lugging.

It is seldom that the standard gearing can be improved upon.
except on the R1150GS which is way over geared at altitude 🙄


Easy solution. Ride at lower altitude.  :3some:
 

Offline BuRP

Re: Gearing for more speed
« Reply #13 on: September 02, 2019, 03:32:09 pm »
except on the R1150GS which is way over geared at altitude 🙄

My 1150GSA nudged 209 km/h near Oudtshoorn.... how fast do you want to go then?  ???
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Offline LouisXander

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Re: Gearing for more speed
« Reply #14 on: September 02, 2019, 03:34:02 pm »
Nee Burp, GS is geared different to the GSA

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Re: Gearing for more speed
« Reply #15 on: September 02, 2019, 03:35:24 pm »
except on the R1150GS which is way over geared at altitude 🙄

My 1150GSA nudged 209 km/h near Oudtshoorn.... how fast do you want to go then?  ???

GSA is geared very differently to a GS, about 13% lower from memory.  :thumleft:
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Offline BuRP

Re: Gearing for more speed
« Reply #16 on: September 02, 2019, 03:50:12 pm »
Dunno overall gearing, but I decided to buy this 'GS' (bought a used one) because it was (and still is I think) the only one with a short 1rst gear.
Except for the downright atrocious (read: it wants to kill you!) ABS it was a fine bike, just not suited for anything resembling sand.
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Re: Gearing for more speed
« Reply #17 on: September 02, 2019, 03:52:19 pm »
Too true Burp. That's why I use the XR600R for sand and dirt.

I run a GSA suspension with uprated coils and the GS is still too heavy

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Re: Gearing for more speed
« Reply #18 on: September 02, 2019, 04:08:27 pm »
I even changed my FD to 32/11 to try and shorten my 1st
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Offline BuRP

Re: Gearing for more speed
« Reply #19 on: September 02, 2019, 04:17:00 pm »
That's why I use the XR600R for sand and dirt.

Funny you say that.
During a Westcoast ride over a deepish sandy 4x4 track where the no-sand capabilities of this behemoth shone I swapped with someone who could ride it there (yes I'm a wuss...), and I took his '450 with big tank'.
After pulling away last I discovered 'whoa, this aint no 450!' and overtook all but for my own bike who'd left first!
Turned out the 450 was a XR650R, and a week later I bought a new one from CIT Pretoria.
Still have it, won't sell it, lekker tractor that  :P
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