www.zxrworld.co.uk

Chain is shagged, front sprocket is worn to shxt, so am replacing front, rear, and chain this month.

Probably gonna go for Renthal with either RK or Tsubaki chain. Question is, which sizes?

Could someone confirm that original sizes are as follows:
Front sprocket: 15 teeth
Rear sprocket: 45 teeth
Chain: 520 size, 110 links

Have read on this forum that 14 front and 47 rear helps perk up the acceleration with a loss of top end speed. Problem is, I'm a back road scratcher AND a motorway speed nut. Exactly how many km/h would get knocked off the top end if I go for 14/47? I want to keep the top speed over 200km/h at least so don't really mind losing 20-30km/h.

Standard L gearing is 15 front and 45 rear at 14500rpm with a 160 tyre you get a theroeticial top speed of 233.0407KPH which is 144.80478MPH


If you fit 14 front and 47 rear then once again at 14500rpm with a 160 tyre you get a theroeticial top speed of 208.2492KPH which is 129.40005 MPH

Standard chain is 520 can't remember the standard number of links but if you go for 14/47 then you don't need the standard links just shove the axle as far forward as it will go and cut the chain to suit.


I'm sure the little calculator for gearing is on the site somewhere if it's not send me you email and I send it to you.

Cheers mate. Think I can probably live with 200kph though my Gixxer mate is gonna make even more mincemeat of me on the motorways than before...

But hey, the lil' Ninja is all about cornering anyways

Do you know how much the acceleration will improve using 14/47? I only want to go down that road if there's a noticeable difference.

I'll hunt for the calc and let you know if I can't find it.

go for 14 45, mine is plenty quick enough accelaration wise with this.

Thanks for the input.

I'm interested to hear what the other users on this forum have...15/45, 14/45, 14/47 etc.

Enough to pull wheelies?

Ive always run standard sprockets on mine, ill have to give a smaller front a try just out of interest

I've been playing around with that excellent gearing calculator one of you recommended on the site

Interestingly, by dropping down the rear sprocket to about 38 teeth (possible to buy 38T AFAM sprockets in Japan) the top speed goes up to 275kph....about 170mph. Now obviously, the engine and tyres are not up for this...but it makes me wonder what the real top speed is for the ZXR400, especially with the right tyres, aftermarket exhaust system, and tiny rear sprocket...anyone know?

Or rather, anyone blown their engine trying?

I very much doubt it will do that speed, theres just not enough power to push it through the wind upto that speed.

which is the point I always try to make to people about downgearing.

As standard the ZXR ought to do over 140mph, but realistically unless you are Dani Pedrosa on a very long straight road you'll never get anywhere near that. I never got past about 115 on standard gearing.

My bike with 14/47 sprockets hits redline at about 130mph in top. but it does it quickly.

So although I've reduced the theoretical top speed, I've increased the top speed I can actually do on realistic roads (closed roads obviously officer). I ride faster with lower gearing.

sorry I can't be bothered to make the conversions to kph.

I regularly rev out around 210-20kph (depending on the wind ) and my friends ride quicker. Surely riding fast in a straight line is about the easiest thing you can do on a bike, don't need to be no Dani Pedrosa, just get your chin tucked down

I have to travel over 150km twice a week, and want to push the journey time down. So that my friend, is the point. But then, I live near a very long stretch of criminally unused highway with no coppers and no rear-facing cameras

Quick KPH to MPH Conversion for those lazy summers:

kph mph
30 19
50 31
60 37
80 50
100 62
120 75
160 99
200 124
240 149

14/45 sounds like your best compromise, standard length chain will work with 14th front, so you could even buy a 15th too and just swap them around as suits ..

I ran 15/44 once, it wouldnt redline in top, and it accentuated the lack of midrange.

if you get a uk spec cdi you gain 400rpm (14,900 rev-limiter) so claw back some of your lost speed.

renthal do odd sprocket sizes for zxr400's, ive got 16/40 on the 400/600, which is too tall, it wont rev out in top, but will lift the front in second ..