www.zxrworld.co.uk

What BHP would a standard zxr400 put out???

i believe claimed power is 62bhp.

prob about 50-55 by the time you get to the rear wheel tho.

anyone had a standard bike dynoed?

I think the claimed power ouput is 65, a few member in the past have had thiers dyno'd, i think wonderpupp was one and she saw a healthy 62hp. SimonHann also had his done, that was putting out a tad over 60.

Taken without 'Those Useless Fuckers' at TTS bothering to free up the rear brake which was virtually siezed!!! So that's bound to have been sapping a fair old bit of hp....

Nice and smooth though:



Oh, and it is of course the before/after dyno from my 444cc rebore!

guess i probably slightly overestimated the transmission losses then,

I think I had Renthal sprockets on when that was done, too...

If you've ever held them in one hand and standard ones in the other, you'll know how huge a difference there is in weight!

yeah I have.

won't make a difference to the power output though.

It should make a difference between crank and wheel output if you lighten the running gear!

How big a difference, I don't know.

*difference in terms of the transmission loss, of course - not overall!

not to the power output at any given rpm (ie what you see on your dyno chart)

may improve the dynamic response (ie how quickly the bike would accelerate) but the inertia of the sprocket is trivial compared even to the back wheel, let alone the mass of the bike and rider.

may also improve the handling due to less gyroscopic effect, but again this is trivial compared to the wheels.

the difference between crank and wheel output is purely how much energy is lost in bearings, gear meshes, the chain, and churning all your gearbox oil around.

Jamz, you are 100% when you say that there is a vast weight difference between the Renthal rear sprocket and the standard ones.

They must weigh a quarter of the standard one. I think the few Renthal ones I have are made of Magnezium or something similar.

MonkeyBusiness wrote:Jamz, you are 100% when you say that there is a vast weight difference between the Renthal rear sprocket and the standard ones.

They must weigh a quarter of the standard one. I think the few Renthal ones I have are made of Magnezium or something similar.

renthal rear sprockets are aluminium alloy, standard is steel, so it's about 1/3 of the weight straight away. add the fact that the holes in the renthal ones are twice the size.

you pay for this with a shorter life than steel sprockets.

still doesn't make a difference to your dyno chart though

All dynos read different as well so dont do too much work on the BHP

My full race bike on one dyno showed 79 bhp and on a controlled dyno it showed 72 bhp at the end of the year after a good thrashing it showed 66 bhp so as you can see weather and climate can mate a lot of diffrence

On my website on Links there is a link to a dyno and some information on how they work click on Dyno - Pro

Who gets to the flag first thats what matters in racing took me 5 years to work that out its not all power good all round set up

I think my bike dyno'd at 67 BHP from sussex rolling road ill have to find the docket as my brother went and had it done when the carbs were set up.

its a 90 H Model,

When i find the dyno ill take a pic