Jump to content

Zz zz zzr600 running lean at low revs


Recommended Posts

Hey all, I've got a zzr600 which I've taken off of the road to sort a few things and get ready for an MOT.

One of the issues I have is that the bike runs lean on tick over, confirmed this by checking the plugs. I've turned the pilot fuel screws upto 4.5 turns out and it still runs lean. I've sprayed easy start around the intake when the bike was running and didn't notice anything straight away, so I'm pretty sure it's not a vacuum leak... I'll have a more thorough go on it again though. The only thing not stock on the bike is a 4-1 exhaust system which is road legal (so has some baffling). Would this make that much of a difference to fueling ? The jets are all factory so haven't been changed yet.

Any advice would be great fully received !


Link to comment
Share on other sites

Hello and welcome to the forum, think you will need to take carbs off and do a bench set up, has it had a dyno kit on it and jet needles to low , are the floats in the carbs the right height, here's a basic ,and old carb adjusting write-up , old but good. What year is your bike. :thumb:

Link to comment
Share on other sites

Heya guys. The issues i've had with the bike is (even with the pilot fuel screw turned out 4 full turns) it screams on choke, which cant be any good for anything.It also doesn't like to tick over when its warm meaning constant throttle blipping in traffic. If it then stalls it can be a pain to start and sometimes i have to choke it.

hesitates to rev off of tick over. This has clearly been an issue before me as someone had screwed the fuel screws about 5 turns out before I got to it.

The plugs are all about the same colour on each cylinder.. so i'm not sure that its an individual carb playing up

Dont get me wrong the bike can be ridden, but i use it for longish distance commuting so want to get it sorted..

The jets are stock sizes. I have'nt check float heights yet. I'm thinking either the airbox is warped and not sealing properly, or the filter element is'nt stock and letting it a lot more air - though like i said it revs up fine so im not sure to be honest.

Ive tried a vacuum test with easy start but couldn't find anything immediately, will try again.

Link to comment
Share on other sites

Zzr are extremely prone to screaming on choke ... they go from 3k to 7k in a heartbeart and if left on choke for too long the headers go a very nice red cherry colour ..

This is quite normal choke operation and requires a tweak on its choke lever to combat .

Link to comment
Share on other sites

Thanks for the replies guys! The valves have been checked in the last couple of months and are in spec. The air filter seems good - i bought a new one on t'net and its exactly the same.

I've just replaced one of the carb bodys as the other one was broken, so carbs may need balancing. regardless, it should be running better than it is...

Link to comment
Share on other sites

Has anyone had to re jet after chainging exhaust systems ? I think the ZZR originally ran 2x 2 into 1 and now is a 4 into 1

Original zzr is a 2 into 1on either side(4 into 2 ) joined by a link pipe


And depending on the performance change of a different exhaust it may require re jetting

I had a standard setup on my 600 (and amotad nexxus on my current 1100 and previous 1100which is a straight swap as it is a cosmetic enhancement so no jetting required .)

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Sign up now

    Registration is quick and easy 

  • Create New...

Important Information

Terms of Use Privacy Policy Guidelines We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.

Please Sign In or Sign Up