ZZR250 wont idle

sash · Post by **sash** » Thu Feb 23, 2006 5:04 am

Hi everyone,
My 1990 zzr250 has had problems idling since I got it last year. I just got it back from the mechanic where the carbies have been replaced, but he couldn't get it idling properly. It will start first go from cold, but after maybe 10-20 seconds the revs will gradually reduce until it dies.
Even when it's warm, it will not idle. This gets annoying at sets of lights, I have to continuously rev it to keep it from dying on me.
Any idea of what's causing this?

Tones · Post by **Tones** » Thu Feb 23, 2006 5:25 am

I would ne looking at the fuel cock to ensure it is getting sufficiet vacuum. Otherwise the usual - compression test, carb balance, float levels, fuel, fuel line, and all other vacuum lines. Failing that, cam timing and the cam chain tensioners.

Cheers

Duane · Post by **Duane** » Thu Feb 23, 2006 6:30 am

could be any number of things
also could be a problem with the motor getting enough air to idle

mrmina · Post by **mrmina** » Thu Feb 23, 2006 11:15 am

try the idling screw

mike-s · Post by **mike-s** » Thu Feb 23, 2006 12:43 pm

as others ahve said, first things first, set the fuel cock to "PRI" for prime, this means it doesnt block the fuel valve when there isnt a vacuum. This will tell you if theres sufficient vacuum to operate the switch.

Secondly i would bump the idle screw up lightly, but your engine should idle at 1100-1300rpm or so from memory. If it does with the idle set much above that, there's definately a problem elsewhere.

How new were the "new" carbies? from the factory? or from a wrecker/another bike? if the latter were they thoroughly stripped and cleaned of goo? if not, theres most likely a blocked jet somewhere. If they were, then i'd get the idle mixture checked out.

Other than that, im flat out of ideas.

Oh oh oh, how are the plugs after they are taken out after a few minutes of idling without revving? the right light chocolate coffee colour? a bit white/ceramic colour? or dark and carbony?

light=lean, coffee clour = on tune, dark/carbony = rich.

sash · Post by **sash** » Thu Feb 23, 2006 1:18 pm

Thanks for the replies.

The mechanic did a compression test, and said it was OK. Timing chain has also been replaced, and new set of plugs too.

The carbs are used, came off another bike. Not sure how well cleaned they are.

I'll see what I can do though, thanks for the ideas guys.