Kawasaki Sportsbike Riders Club - Australia - Online Forum

I've had my newly refurbished gpx out for a couple of rides around the block (only done 150km) and I'd like to know the following;
Is 32psi tyre pressure right? Is 100kmh @ 6,700rpm good? Should I stick with the 15/45 sprocket combo? The original gpx motor had a 14 on it. Up one on the front is better for top end, yes?
I did try a search for this info, but I can't 'refine' it enough to reduce the number of posts I had to sift through.

6,700rpm for 100km/h seems awfully low for a 250, I'm pretty sure my GPX was doing about 9-10,000rpm at the same speed...but I did have standard sprocket sizes.

32psi seems a bit low as well, my ZZR has 36psi in the front, 42psi in the rear, I'm pretty sure the GPX was around the same pressures.

most of ur questions are subjective...

i run 34/36 psi in a 900cc bike on the road on a average day- if its real hot i can put a few more in..if real cold ive been known to drop a few - depending on the ride of course. I also bump em up to abt 40/42 when commuting a lot.

as for the sprocket..its a "suck it and see" thing... if it takes too long to get to speed, then change ur ratio- however the ratio u got is better for top end and mileage compared to less teeth on front. If they arent stuffed, dont change em till they are.

to be honest, i think both these issues are more for experienced riders to worry abt- right now ur job is to learn how to handle ur new bike to the best of ur ability, concerntrate on looking out for dickheads, and getting lines sorted & that sort of thing, the rest u will learn as u ride.

they are simply not questions that have a right or wrong answer...

The vin on the frame of my ninja250/gpx250 says 28 psi for the front and 32 psi for the rear, although Ive heard of people running 30 and 34. At 60 mph/100kmh I think Im pulling around 8000 rpm in 6th. Your bike should be pulling less rpm's because of the 15 tooth front sprocket. As far as the 15 tooth front sprocket helping your top end it will increase your gas mileage and be easier on the engine but I doubt it will increase your top speed. The 15 tooth sprocket will slow down your acceleration a little.

Neka79 wrote:most of ur questions are subjective...

Cheers, but experienced opinion is always welcome.

i run 34/36 psi in a 900cc bike on the road on a average day- if its real hot i can put a few more in..if real cold ive been known to drop a few - depending on the ride of course. I also bump em up to abt 40/42 when commuting a lot.

Yeah, the book says 28/32, but I've got 36 in them at the moment. I figured it would be easier to let a couple out if it doesn't feel right. I had noticed that a few people have said the book pressures are a bit low.

as for the sprocket..its a "suck it and see" thing... if it takes too long to get to speed, then change ur ratio- however the ratio u got is better for top end and mileage compared to less teeth on front. If they arent stuffed, dont change em till they are.

Top speed isn't going to be an issue. On my L's I'm only *supposed* to do 80 anyway. I am more interested in getting good fuel economy. It doesn't have the acceleration of my old YZ - but I think I can live with that.

concerntrate on looking out for dickheads

Believe me Nathan, the colour of this bike makes almost a certainty that even the numbest nut will see me first. But I still watch out for them just to be sure.

Daisy wrote:

concerntrate on looking out for dickheads

Believe me Nathan, the colour of this bike makes almost a certainty that even the numbest nut will see me first. But I still watch out for them just to be sure.

neka is all excited, now u've called him nathan

Shit Neka
with comments like that I can see you keeping your license for longer than it takes the ink to dry this time

Rossi wrote:Shit Neka
with comments like that I can see you keeping your license for longer than it takes the ink to dry this time

i figured for the 7000odd posts its abt time i said sumthing worthwile..a bit like silent bob.... hehehe...

neway i hope my points came across not too "smart assy" as i wasnt intending that... i was really trying to re-interate learn to walk before u run...

i think theres a reason they dont put too much technology into 250's (other than cost) is cos they dont want learners to funk around with everything... give em basic suspension, basic brakes, shit like that so they learn to ride the bike the way it is...



and lets not get too excited Rossi...

and who bloody called me Nathan?? thats NOT on..

Neka79 wrote:and who bloody called me Nathan?? thats NOT on..

Your mother, I believe?

Neka79 wrote:neway i hope my points came across not too "smart assy"

No, they were perfectly sane and rational. So were the comments you made in this;
http://www.ksrc-au.com/phpBB2/viewtopic ... highlight=

So who are you, and what have you done with Neka?

not the same bike but on my 2r when i had that i used to run 28f and 32r that felt pretty good however i did about 7000km on it and i was due for new tyres

Daisy wrote:I've had my newly refurbished gpx out for a couple of rides around the block (only done 150km) and I'd like to know the following;
Is 32psi tyre pressure right? Is 100kmh @ 6,700rpm good? Should I stick with the 15/45 sprocket combo? The original gpx motor had a 14 on it. Up one on the front is better for top end, yes?
I did try a search for this info, but I can't 'refine' it enough to reduce the number of posts I had to sift through.

Up one on the front is better for top end, yes..
on my wifes GPX we put a 3 tooth smaller rear on it (same as 1 up on the front) for the trip to P.I. It ran much better at higher speeds and the loss of lower gearing was hardly noticed..

Daisy wrote:No, they were perfectly sane and rational. So were the comments you made in this;...So who are you, and what have you done with Neka?

The Sans Licence Syndrome is a depressive cycle that sees the patient move from deep depression and heavy drug abuse, and hatred of those with bikes to the highs of brotherly love and sage advice. Of course the fact your name is Daisy rather than Donald means you have the "good" Neka.

frogzx12r wrote:...Of course the fact your name is Daisy rather than Donald means you have the "good" Neka.

Touche !!

My stock GPX250 does 8000 RPM at an indicated 110 (real speed 100). So 6700 sounds pretty right at an indicated 100 km/h. 8000*(100/110)*(14/15)=6788 RPM

Unless you're revving past peak power at your max speed, a 15Tsprocket shouldn't make you faster. Slower if anything.