zzr600 lumpy below 3000rpm and also smells of petrol

[ddtwelve]

Hi all I know its not a fazer etc but my brother brought a old zzr600 only done 6500miles,when he first got it it wouldn't run proper felt like it was a cylinder down so went back to stealer who sort of sorted it said there was sand in air filter, so carbs were clean etc etc weve got it back it will start and run but its  lumpy below 3000rpm and also smells of petrol went out for a ride to squires and still not any better any ideas on what to do as don't want to take it back to dealers

cheers

[Mark YPVS]

make sure the air box is on properly, check the choke isn't sticking, check for air leaks, carb top rubbers( cant spell diaphrams) , make sure the carb filters for the coolant are clean as well, then plugs, leads , caps etc
Mark

[rustyrider]

If it's old but done hardly any miles that suggests it's been sitting around for a while.  Carb diaphragms would be the place I'd be looking.  If they are leaking (perished or split) it'll run rough at low revs, particularly when going from closed to open throttle, but be OK once you get the revs up.

[rayburn600]

Sounds like its flooding.
More than likely a sticking carb float needle seat.
Either needs more cleaning or a new float needle seat.
Take it back they need to re-look.

[ddtwelve]

will pass it on to my bro hope he dosent come running to me for my tools

[Arfa]

Is in one of the really early ones or the '93 onwards Ram-air ones? If the latter, make sure there's no leaks on the air box. My wife's had a big gap between base of air box and top of throttle bodies (swapped box and got new seal). Also check the access holes on the box are plugged properly. It's important the air box build up the correct pressure to get the carb floats right to then get mix of air to fuel correct.

If it stinks of petrol, double check fuel lines etc. They're very easy to split (found out hard way).

Does it run ok at higher revs?

[Simon.Pieman]

 It's almost certainly the sidestand cutout switch. Squirt some WD40 on the little plunger that should be getting pushed in by the stand and check it's connectors. I've had both a ZZR600 and a ZZR400 in my garage that suffered from this -sorting the cutout worked in both cases. (after I'd had the carbs and airbox out twice trying to find a problem) Don't ask me why the cutout affects it this way, it befuddled me too.