Z9 A4

[DonB]

Bike starts up but occasionally spits back out of the carborettors.

Can anyone help?

Many thanks in advane

[Ultim8pc]

I'd start with:
Valve clearances
Leaky valve seat
Incorrect ignition timing
..

[Big Fluff]

Defo sounds like tight inlet valve clearences.

[johny brando]

Bike starts up but occasionally spits back out of the carborettors.

Can anyone help?

Many thanks in advane

Hi Don, Never got the bottom of this one ! I think it may be induced by a slightly lowish vacuum when cold ....my one has always done this on occasion it can spits a couple of time whilst cold then it settles !!!!!! Can tell you now lots of other Kawa 900,s do it too & as soon as the motor has warmed up a bit, it normally disappears & it's not then seen again until another cold start up down the line . You can check your plugs/caps/leads & coils ,valve clearances, compression & timing etc as that won't hurt.... as any of those with issues can encourage spit backs ......but to be totally honest my motor is very good internally 140 psi on all cylinders- Mk2 ignition - s/Steel valves-dialled in std Cam's & everything is spot on = recently fully rebuilt by me & it used to do that too prior to the full rebuild I did that wasn't even called for...I'm just a bit OCD haha ! If it doe'snt do it when it's hot.. best ignore it & just enjoy the bike Don as there no point chasing a disappearing shadow ! All the best Johny B.

[ZedHead]

Sounds like valve timing may have slipped. Don't try to start it until this and shim gaps are checked as per the service manual

[Ultim8pc]

Agree with Johny that some spitting when cold is fairly normal. If it's still doing it when warm then my original advice still stands.

[ZedHead]

Agree with Johny that some spitting when cold is fairly normal. If it's still doing it when warm then my original advice still stands.

Mine 'coughs' through the exhaust a bit when cold but my thoughts are are that spitting back through the carbs implies an inlet valve is opening during combustion or on a wasted spark.

[Pigford]

Agree with Johny that some spitting when cold is fairly normal. If it's still doing it when warm then my original advice still stands.

Mine 'coughs' through the exhaust a bit when cold but my thoughts are are that spitting back through the carbs implies an inlet valve is opening during combustion or on a wasted spark.

Can be fuel icing.

[Ultim8pc]

Agree with Johny that some spitting when cold is fairly normal. If it's still doing it when warm then my original advice still stands.

Mine 'coughs' through the exhaust a bit when cold but my thoughts are are that spitting back through the carbs implies an inlet valve is opening during combustion or on a wasted spark.

I would agree, if it does it when warmed up.

[johny brando]

Agree with Johny that some spitting when cold is fairly normal. If it's still doing it when warm then my original advice still stands.

Mine 'coughs' through the exhaust a bit when cold but my thoughts are are that spitting back through the carbs implies an inlet valve is opening during combustion or on a wasted spark.

I would agree, if it does it when warmed up.

Roger that........were on the same page !