bad hot idle on gpx250

hey guys, been having a prob with the gpx for a while now, its fine when cold or at normal temperature, but after a bit more spirited riding (taking it over 7 or 8k between shifts) or long rides out of town the idle isn't very good and it tends to 'cough' a little bit at times and will sometimes stall. The temperature guage at the time is still in the normal range (less then halfway). Its not very confidence inspring, especially riding around in the city, and i have to compensate by keeping it idling around 2000 when i've heard it cough. It currently idles at 1500 rpm (oh and air filter is clean). Any ideas? I'm thinking idle mixture although that is really just a guess thanks in advance

dave

davesta, Sounds like it is running too rich, you could do a plug chop on it to find out, and don't use opimax if it has carb's
Cheers and good luck with it.

yeah mixture is about the only thing i can think of (not that i'm a pro tho). I don't use optimax (heard too many bad things about it), i just use shell or bp unleaded usually. Another thing to add is that it feels down on power compared to other 250's. On a ride today the hyosung gt250's were kicking my arse, especially at the lights. I know they're newer and dont have 30,000+ klicks on them plus a bit more power (and the riders were prob lighter) but there was a bit of a difference. A guy on an aprilia rs125 kicked my arse as well on long sweepers to straight roads. Up a really long steep hill a guy on an old zzr250 got me, so i cant be putting out as much power/torque as i should be. Can anyone recommend a good place to go to have the mixture checked? Is this best done by a place with a dyno? I'll have to check the colour of the plugs, havent had time yet. I know its only a 250, but i've gotta do my time till next year and if anyones gonna notice a few extra horses its gonna be me!

Hi Davesta,

Have you had any luck with your problem? I have a GPX250 that is exhibiting some of the same sorts of issues you are describing (not all though)

something well worth checking and doing the mod anyway

when they geta few kays on them and get a bit of piston gas blowby they start to have a bad idle

there is a crankcase breather pipe exits the motor at the base of the airbox and then this hot oily air then gets pumped into the airbox which your motor then sucks down and doesnt like too much

this is a pollution thing

you take the pipe from the airbox , plug the airbox hole and then put a little filter onto the hose and possibly you may need to put this into a catch can = old coke bottle in case its pumping oil out as well

your motor will now be sucking nice cool air and running a whole lot happier