jetting?

hello all, my name is tim,i live in st.aug fla and have been riding kz,s at one point or another all my life. i have a 77 kz 1000 totally restored it my self. lowered it,and stretched it.The bike is stock except a vance n hines pro drag sidewinder pipe. k and n filters and excell coils.i was running 36mm mikuni flatslides on it,but it kept loading up,so i bought new intake manifols, and new filters and put on a stock set of 28mm mikunis. it runs good, but when i approach mide range in any gear,it boggs down and sputters, when i pull up the choke it smooths out considerably. any suggestions??? thanks and i am glad to be a new member of kz.riders... Tim fox

Sounds like a bit lean on the midrange adjustment. You can try to remedy this by reclipping the jet needle to the next richer position. For example, if it is currently clipped to the #3 position you would want to adjust it one step richer to #4. The 5 positions on the jet needle count from top to bottom 1 to 5.

Welcome to the site...post some pictures when you get a chance.

Good luck.

Post edited by: savedrider, at: 2006/01/10 19:00

Definitely lean. To get main jet right full throttle run, hit kill switch, coast to stop, check plugs, black center insulator rich, white lean, tan-brown just right. This gets main jet right. About 1/2 way on throttle bike running on main jet. Fine tune with pilot, air jets and needle position for part throttle openings.

What did you do with your 36mm carbs?

RSK wrote:
quote About 1/2 way on throttle bike running on main jet. unquote

At half throttle, the bike is running on needle jet and jet needle with a small contribution from the pilot jet and air jet that feeds it. That is why half throttle is called mid-range. You need to have the slides fully opened for the main jet to be the main source of gas although it meters gas for the jet needle/needle jet at all times so in a sense, plays a part in the mid-range.

Without knowing what carburetors are being discussed in this thread, there is no way to give specific advice.

Wired is the site's carb guy, so my bad. Should have said running mostly(?) on main jet. My carb experience mostly in slower bracket drag racing. All I have ever cared is how it runs from 7000 rpm to 11000 rpm at wide open full throttle with 1/4 turn trhrottle, velocity stacks and a Hindle sidewinder.

Although I do think mid-range is midway on rpm scale to redline. My 95 GPZ1100 gets 5500rpm on a whole lot less than 1/2 throttle.

Again Wired is site's carb guru. If in doubt go with his info.

Post edited by: RomSpaceKnight, at: 2006/01/11 15:39

There isn't much art to figuring out where the slides are at a given throttle position. When reassmembling a set where you have the slides in the carb bodies and bolted into position with the throttle butterfly but not yet having the spring on, it is easy to move the throttle butterfly to its 1/2 open position which corresponds to the slides opening half way. Its at this point where I generally set the maximum slide height since many sets I work on are mis-adjusted. The max height should be at the top of the venturi opening and there is a limiter screw on every set that works as a slide stop. The reason is that if the slides are allowed to open even further than this point, the jet needles run the risk of coming out of the needle jets. If that happens, they MAY not reseat and would cause the slides to stick open. A set of slides open that much means you would need to remember how to hit the kill switch immediately as the bike would probably blow up from over revving before you crashed otherwise.

hello all, and thanks for the help. i tried reclipping the jet needle to make it run richer.now it seems the bike is running on only 2 or 3 cylinders, i cleaned and checked the gap,and i am getting spark. these are a set of totally stock 28 mm mik carbs,new manifolds,accel coils and vance/hines pro-drag exhaust.. i will post pics soon,i am quit proud of the bike and cant wait to show it.. thanks all,and any further help would be greatly appreciated. thanks Tim Fox

sunworshipfire wrote:

hello all, and thanks for the help. i tried reclipping the jet needle to make it run richer.now it seems the bike is running on only 2 or 3 cylinders, i cleaned and checked the gap,and i am getting spark. these are a set of totally stock 28 mm mik carbs,new manifolds,accel coils and vance/hines pro-drag exhaust.. i will post pics soon,i am quit proud of the bike and cant wait to show it.. thanks all,and any further help would be greatly appreciated. thanks Tim Fox

Do you still have the 36 flatslides? looking for a set? u2u me .

yes, i still have the 36mm flatslides,not having any luck getting the stock 28mm carbs to work, i am thinking about putting the 36 carbs back on after i try to adjust the needle on them... pics coming soon.