bike fell over, now acting funny (carbureted)

[Matty8]

2007 Kawi ZZR-600 (Carbureted).
Bike fell over in the driveway this morning (was not running). Started up fine and rode it to work, nothing unusual. 8 hours later at work I started it up fine again, but after rolling the choke off I realised it was idling very low (1k vs the usual 1.5k), and it sounded abnormal. I increase the idle back to 1.5k with the adjuster knob, but it still sounded off; a different tone/beat is the best way I can describe it.


Also the rpms are sluggish to drop down now. When pulling the clutch in from about 4k rpm it took maybe 2 seconds to drop to idle, when it would normally plummet down in 0.5s. Although I'm wondering if this is just a symptom of increasing the idle screw, i'll have to try lowering it back down and test that out.

Other details:

• power still seems OK (although never took it above 6k)
  
  
• still rides smooth
  
• idle is still smooth, even at 1k I don't recall it being very choppy
  
  
• choke still operates properly
  
  

What could the issue be? And where would you start?

 

[taximan62]

Just off the top of my head, some gunk broke loose and got stuck in one of the jets or maybe the float in the carb is stuck??

 

[Matty8]

Just off the top of my head, some gunk broke loose and got stuck in one of the jets or maybe the float in the carb is stuck??

Thanks, definitely helpful. My only game plan at this point was to pull the carbs, so this encourages me. If anyone has any other easier things I could check first, that would also be great.

 

[TwistedKestrel]

In all seriousness I would try an Italian tune up before doing anything else

 

[GreyGhost]

Also check for possible air/vacuum leak from a hose or carb boot getting dislodged.

 

[Baggsy]

Could try marking and then adjusting the idle screw. See if anything changes when you try to bump the idle back up to spec.

 

[JFD]

In all seriousness I would try an Italian tune up before doing anything else

in all my life, I've never heard this before...

 

[GateKeeper]

in all my life, I've never heard this before...

really.....

probably just us old guys get it then....

https://en.wikipedia.org/wiki/Italian_tuneup

maybe this one then

"ride it like you stole it"

.

 

[Baggsy]

in all my life, I've never heard this before...

Never hung around an Italian car dealership here then, eh? People would buy a Ferrari, cruise it up and down Yonge St., and then complain about poor performance.

 

[TwistedKestrel]

probably just us old guys get it then.....

 

[yodude]

i'd pull the plugs, one is prob gonna show diff than the others the longer it keeps up, good bet something simple on the outside got knocked loose, vac line, plug cap etc,

i'd check all that & simple quick easy to get at external stuff out first before pulling carbs

not sure if ok to pull plug caps, one at a time then re-attach, on that bike with the engine running but if yes, i'd check that out

lower idle rpms drop could be a misfire something on one cyl, usually acts up or can be more noticeable there vs high rpms, a slow higher rpms drop is often a air/vac leak

 

[RockerGuy]

Next time I get pulled over by the po po, I am telling him I am doing an Italian tune-up

 

[inreb]

Also check for possible air/vacuum leak from a hose or carb boot getting dislodged.

"This. So much this" PrivatePilot
Also some of vacuum port cap leaking or off.

 

[SNAFU]

Probably a float or two got hung up after the drop. Check fuel level for each of the carbs.

 

[boyoboy]

if a carb float hangs up it will leak gas through the overflow

 

[SNAFU]

Depends if fuel valve is operated by vacuum

if a carb float hangs up it will leak gas through the overflow

 

[Matty8]

I started stripping the bike down already, before reading the second half of these comments. I plan on pulling the carbs on the weekend, hoping it will be something obvious to the untrained eye, because I've never done this before! Thanks for all the replies so far, I will update with any news on the weekend.

 

[boyoboy]

Depends if fuel valve is operated by vacuum

use prime, or have bike running.

 

[PrivatePilot]

Also check for possible air/vacuum leak from a hose or carb boot getting dislodged.

"This. So much this" PrivatePilot
Also some of vacuum port cap leaking or off.

Well, I was going to concur with GreyGhost as well, but I see I already did LOL.

 

[Matty8]

Carbs have been thoroughly cleaned. They looks pretty good to me (cleaned 1.5 years ago), although there was a possible blockage for one of the fuel inlets or outlets in one carb, and a pilot jet or two partially restricted. Hoping that will do the job, but there was nothing that really stood out. will give the spark plugs a look over, and then test tomorrow.'

EDIT: oh and one other thing, we noticed that one throttle body is just noticeably more opened than the other three. Could this be an issue? worth trying to adjust?