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Discussion Starter · #1 ·
Hello all,

I am brand new to the thread but could really use some help from the experts. I have a 2008 zzr 600 and recently its been idling strange and the rpms seem to hang around the 4k mark. I have cleaned the throttle cable and I am positive its not hanging up at all because with the fuel tank removed I can see the butterflies open and close no problem. When I get on the throttle hard it seems to clear up but down a little on power. At an idle if I rev it up the rpms will hang around 4k and sometimes don't come back down unless I put it in gear and release the clutch slowly. I recently installed block off plates hoping I could get lucky and replace a bad vacuum line but it hasn't changed a thing.

Does this sound like a vacuum leak? Does anyone know what steps I could take to maybe start a process of elimination. Also is there a diagram out there that can show me all the vacuum lines?

Thanks in advance all this has been so frustrating as I just wanna ride!
 

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Hey wheelz... and welcome to the ZX Forums... You can do a few things to check for vac leaks... if you set it up on a portable tank so you can run it with out tank on it, you can spray some carb cleaner or something flammable , be careful and have fire extinguisher close.. but spray around the outside of carbs at different connections where leak could happen... check that the hose clamp looking clamp around the carbs are tight and no tears or holes.. this is the rubber mounts between carb and motor.. same with any vac lines... before spraying, take a good look at them all with a bright flash light..including the carb mounts, the rubber between carb and motor, You can also eliminate other things, like disconnect the cables from carbs and try in manual with cable to see if same thing happens.. try to eliminate the free things first, this even before trying the spray thing... look close at everything with bright light... if it still does it without the cable hooked up, you can eliminate cable... my experience is that it is usually the hose clamp that tightens the rubber mount to the carb.. those are tough to tighten sometimes and they get half assed when replaced... have also seen where screw driver slipped and poked hole in one. Take a look around 360 degrees around the base of carb looking for nipples where vac hose should be and maybe missing... check both ends of hoses, as well as along the hose to be sure not split.. Do those things before spraying anything, as to keep from having to if possible.. spraying flammable liquids on a running motor is a last resort thing... move any gas or flammable things far away before doing as well.... plan on there being a fire, so you will be ready if one happens... you can also try covering the breather side of the carbs while running if you can access the area, should make motor die almost instantly if no leak or sucking air somewhere else.. You can check you tube also for some of these ideas to see if anyone else has done the same things on their bike and video'd it... maybe save you some time.. these are just ideas and suggestions.. make it your own and be safe with what ever you do... playing with fire is playing with fire...

good luck

Johnny
 

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Discussion Starter · #3 ·
Thank you Johnny! As soon as I get home from work I will be tearing the bike down and looking over the lines and start with the hose clamps around the carbs. Are you saying to just unhook the throttle cable to the carbs and run it to make sure it isn't a cable issue? That makes sense! I will be sure to post as I progress through the diagnostic work.

My plan was to rig up my tank with a longer fuel line and spray around certain areas but I will check everything thoroughly before I start flirting with a fire disaster haha.

Thanks again for your help Johnny and I will let you know what I find!
 

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Thank you Johnny! As soon as I get home from work I will be tearing the bike down and looking over the lines and start with the hose clamps around the carbs. Are you saying to just unhook the throttle cable to the carbs and run it to make sure it isn't a cable issue? That makes sense! I will be sure to post as I progress through the diagnostic work.

My plan was to rig up my tank with a longer fuel line and spray around certain areas but I will check everything thoroughly before I start flirting with a fire disaster haha.

Thanks again for your help Johnny and I will let you know what I find!
No problem bruda... Yea, the base of the carbs where they hook to the motor, there is a, what looks like a radiator type hose clamp... make sure the carbs are pushed into the 'boots' and the clamps are tight.. look at the carb and see if the same depth is across all of them to be sure they are seated all the way in and that the boots don't have any cracks or holes.. they take a lot of abuse and it is common for them to need attention... the head of the screw on the clams can be hard to get at without a long screwdriver or a long 1/4" socket/extension set up.. and they get rounded and the screw driver slips and they don't get tight enough a lot of times.. you can ususally find good used ones on ebay if that is the issue... just take your time and go slow.. use a lot of light and look at everything you can before doing any spray work..

let us know how it goes bruda

Johnny
 

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Discussion Starter · #5 ·
Sooo... My bike is running like a champ again! You were spot on! All four hose clamps around the carb boots were finger loose! The boots themselves all looked good I even pulled the carbs out to get a closer look and couldn't see anything. Tightened everything down properly and whala! Johnny thank you tons for the online diagnostics let me know where to send the check haha.

In the future this will be the first place I go for any mechanical help, thanks again!
 

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Sooo... My bike is running like a champ again! You were spot on! All four hose clamps around the carb boots were finger loose! The boots themselves all looked good I even pulled the carbs out to get a closer look and couldn't see anything. Tightened everything down properly and whala! Johnny thank you tons for the online diagnostics let me know where to send the check haha.

In the future this will be the first place I go for any mechanical help, thanks again!
No problem wheelz... glad to be of help. This is a great site, these guys here have helped me countless times... there is a lot of help here.

Good luck with your ride...

Johnny
 

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Hey, I have the same issue with my ZZR. Hangs at around 3k before falling back down. Sometimes it sticks to 3k. I'm not mechanically inclined and I know taking it to a mechanic will cost me more than I want for such a simple fix. Will me continuing to ride the bike in this condition hurt or damage it in any way? Or can I wait till I get it fully serviced to fix this issue and just deal with the annoyance for now? Appreciate your feedback.
 
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