WR400 chain/sprocket question


8 replies to this topic
  • tonytone

Posted February 03, 2008 - 10:42 AM

#1

hi there,

my wr400 is currently running on offroad wheels with 13-42 front/rear sprockets.

will it make a massive difference to run 13-45?

I want it to be comfy at around 50-60mph and not jerky at low speeds

any info would be great.

thanks.tony.

  • Frostbite

Posted February 03, 2008 - 10:57 AM

#2

hi there,

my wr400 is currently running on offroad wheels with 13-42 front/rear sprockets.

will it make a massive difference to run 13-45?

I want it to be comfy at around 50-60mph and not jerky at low speeds

any info would be great.

thanks.tony.


Running a larger rear sprocket will increase engine RPM at 60 MPH, is that what you're trying to do, or are you looking for a "higher gear" to lower the RPM?

3 tooth change on the rear sprocket won't be a massive difference, but you will feel it. The bike will feel a bit snapier and will rev a bit quicker between gears.

I find it easier to change front sprockets and can get away without buying a different length chain. I have 12, 13,14 and 15 tooth front sprockets and can swap without changing the drive chain. It's quicker too, no need to remove the rear wheel.

A 1 tooth difference on the front is similiar to a 4 tooth change on the rear sprocket. I also have a couple of rear sprockets, so I could fine tune if I wanted, but I don't. I used to Roadrace and we'd fine tune for each track, but non-racing I find the front only changes work fine.

  • tonytone

Posted February 03, 2008 - 11:15 AM

#3

thanks for the quick reply Frostbite.
it does get some road use and some green laning but i dont go flying about......60mph is more than enough but i would like the bike to be a little bit quicker off the mark :worthy:
im fitting a 45t because i got a brand new one (and a did chain) when i bought the bike and it seems a shame not to use em.....plus i only have to buy a new front sprocket :busted:
do you know how to calculate the approx top speed i would have with 13-45?
thanks.tony.

  • Frostbite

Posted February 03, 2008 - 11:30 AM

#4

thanks for the quick reply Frostbite.
it does get some road use and some green laning but i dont go flying about......60mph is more than enough but i would like the bike to be a little bit quicker off the mark :worthy:
im fitting a 45t because i got a brand new one (and a did chain) when i bought the bike and it seems a shame not to use em.....plus i only have to buy a new front sprocket :busted:
do you know how to calculate the approx top speed i would have with 13-45?
thanks.tony.


Well then the 45 rear is a good choice for you since you already have it and a chain, and you're looking for quicker response. As for the top speed calculation, that's too much math for me on my day off.

J/K, I've never done the math, partly because it's not all about the math, (even though my 5th grade teacher would disagree) and partly because I'm a carpenter, and the #1 rule in carpentry is "avoid math whenever possible!".

If your bike will pull redline in top gear now in stock form, I'd guess that with your 45 T sprocket, your new top speed at redline would be 5 to 8 MPH slower. If your bike wouldn't pull redline in top gear with the stock sprockets, you may get the same top speed with the new sprocket, or you may actually get a higher top speed since it may put the engine in a better portion of the powerband.

I've seen this with some older street bikes that wouldn't pull redline in top gear in stock form. Guys changed sprockets to make them quicker out of the hole, and were worried about sacrificing top speed (and you would if you strictly go by the math) and their bikes actually went faster and quicker. You may get the best of both worlds.

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  • tonytone

Posted February 03, 2008 - 12:02 PM

#5

it sounds like the 13-45 is just what i want......lucky really :ride:
the bike pulls really strong in all gears and losing a few mph in 5th is no worries......but if by some chance it gets a bit extra of both......so be it :worthy:
thanks for the help. :busted:

  • Frostbite

Posted February 03, 2008 - 12:10 PM

#6

it sounds like the 13-45 is just what i want......lucky really :blah:
the bike pulls really strong in all gears and losing a few mph in 5th is no worries......but if by some chance it gets a bit extra of both......so be it :ride:
thanks for the help. :busted:


Anythime, that's what we're here for.:worthy:

You don't know where I could buy a good fire extinguisher do you?

  • tonytone

Posted February 03, 2008 - 01:39 PM

#7

im from the uk bud.......would cost u a fortune in postage :busted:

  • Frostbite

Posted February 03, 2008 - 08:17 PM

#8

im from the uk bud.......would cost u a fortune in postage :busted:


I was kidding around, an inside joke from my "having a bad day thread."

Cheers

Frosty

  • tonytone

Posted February 03, 2008 - 11:45 PM

#9

im new here :busted:




 
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