more power?

Nah its a 1988 2kr with EXUP. Nothing wrong the engine, i'm just a bit used to the power after 8months riding it and wouldn't mind a bit more acceleration.
Thomson, it depends how many more/less teeth the new sprockets have as to how much it'll affect the bikes performance. Standard sprocket sizes for the fzr250 i believe are front: 17 teeth, rear: 55 teeth - which makes up the final drive gear ratio.
Let us know what sizes you are changing to - i'd be very interested in how it goes 'cos i'm not too sure what to do myself. Keep in mind you might affect fuel economy as the bike will be revving higher to get the same speed as before (eg if you were doing 10000rpm to get 100kph before you might now be doing 10500rpm - just an example)

 

For reference as to how much a sprocket change can help acceleration; i've got a couple of examples that may help your decisions.

I ride a 3LN FZR, and my good mate rides a GPX. I always cane him off the lights no matter how well he launches. He got rather sick of this, as through the twisties he would usually put a few metres between us, but as soon as it came to a straight the dash from 60-110km/h would see me catch up no problems at all.
When recently getting his chain and sprockets done he decided to go up 2 on the rear. Whilst not immediately obvious that it made any real difference, we pretty quickly discovered that it was now pretty much on par between his GPX and my FZR at the T.L.G.P. So there ya go, 2 teeth on the rear is enough to give it a little more poke. Interesting to note that he didnt end up losing ANY top end speed! Turns out that the torque provided from the little GPX motor couldnt get the engine to redline in 6th gear - so he now has quicker off the line speed and the same top speed; albeit at a higher rpm.

My second example oddly enough also involves a GPX. In this case, the owner was rather bored of the lack luster performance of the GPX and never intended to do over 150km/h (this was very important!). The first change was to go 1 down on the front and 3 up on the back - quite a dramatic jump if you ask most knowledgable people! Whilst he was impressed with the acceleration, he decided to go all out and spend the extra $15 on a 2 down front sprocket. Once that was fitted, the little GPX would power wheelie through first and second... and would get light in the front end in third (supposedly). I can vouch for him getting lift-off in first and second though! Quite insane if you ask me; but he found it extremely amusing and it saw him through the final 2 months of his restrictions.

Just FYI; the general rule of thumb is that 1 tooth down on the front equals 3 up on the rear. Most people prefer to go up a couple on the rear BEFORE going down one on the front as the tighter turning radius of a smaller small sprocket arguably wears the chain out faster.

I'm looking at changing my ratio's but i like my top end speed too much (i go chasing ZX9R's & R6/R1's too often so losing top end speed would be a problem). If i do change, i'll probably go up 1 on the rear so as not to change my cruising RPM's too much.

Also, in regards to gaining more power... the best advice i can give an FZR owner is to go get their carbs cleaned & balanced. Depending on their state of tune it will either improve or dramatically improve performance. Since getting my bike tuned i've discovered what a tank slapper is; hard on the throttle in second gear screaming through a couple of twisties and the front end got rather light.

 

I'm gonna assume that your buying a couple of extra sprockets so you can play around and see what works for you - otherwise i'd be wanting to buy a full fresh set of front, rear & chain in one go. It's unwise to play mix and match with varying aged bits unless your a stunter.
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Eeek, only 800km's. For me that would mean i had it installed 3-4 days ago! <!-- s --><img src="{SMILIES_PATH}/icon_cool.gif" alt="" title="Cool" /><!-- s --> Especially on nice weekends its not too uncommon for me to clock up over 1000km's.

Anyway, let us know how the sprocket change goes. As i (think i) said before... i'm keen on getting a couple of sprockets for various uses but am hesistant given the higher rpm for highway cruising. For me, 8700 @100km/h is high enough.