Hey, so i recently bought this bike, a cbr 600 f3 1998 with lots of kms on the clock, 93 000km to be exact, it runs completely fine when its warm, but when its cold i constantly have to keep it going with the throttle untill its had time to warm up, this morning though it wouldnt even start, i live in norway and it was extra cold and wet this morning so maybe that had something to do with it making the air extra dense and ****ing up the mixture making it run even leaner. I suspect the problem is because it has a aftermarket slipon exhaust and proboably hasnt been re jetted, but i was wondering if this can be fixed by adjusting the pilot screws or will i need to rejet it or put the stock exhaust back on? I never tried it with the stock exhaust but i got it along with a bunch of other stuff when i bought it .

 

When it's cold here I turn the idle screw in a turn or two (to increase idle speed), choke on, start, let it warm until it starts to sputter, choke off, then turn idle screw back out until it gets back to 1200rpm. Just make sure you don't lose track of how many turns you've messed with the idle screw. Hope this helps!

 

it got worse, it woulnt start at all eventually, had to roll start it.

Took her apart and checked the valves, turned out none of the inlet valves had any clearance whataoever so it basicly had no compression, adjusted them myself and now it starts and runs like a pure dream again, love it ! Saved alot of money compared to if i was gonna let some workshop fix it too so im happy again

 

That's interesting. Usually when the clearance is tight, when it warms up and things expand, that's when loose power. But then again I'm thinking about push rod engines. Perhaps OHV engines may be effected differently, interesting.

Glad you sorted it out.