Kawasaki Ninja ZX Forum banner

1 - 14 of 14 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter · #1 ·
Bike had been sitting a year and I rebuilt carbs on my 99 11d. did a complete disassemble, 2 day soak in permatex followed by a blow out and spray out and a rebuild consisting of new float needles and seats, orings on the pilot screws. Slide diaphragms look good and the carbs seemed to synch ok, as well as the float height check out to the best of my measuring ability. I didnt really see much varnish or crap in carbs when disassembling, and carbs were set with a motion pro mercury type synchronizer, however did notice all four slides not rising together when throttle cracked open, even after syncro job. Bike idles good, starts immediately, and and performs adequately around town but if put on a load such as a steep hill or forced to accelerate quickly in ranges north of 3500 rpm, bike begins to cut out, spit sputter etc. I am thinking that my carbs still have issues most likely in the slide diaphragm area and are still not synched correctly being as they do not rise together. I have replaced the fuel filter, tested the fuel pump, and set the pilot screws in ranges from 1 5/8 out to 2 1/2 turns out to no satisfaction. Also, if you push it up to around 7000 sitting on the center stand and hold it, it will begin to blubber and stumble. Motor is stock and is usually fueled with Citgo 110 octane, ocassionally 93 depending cost. I have a Vance and Hines Programmable CDI that I even tried, no help. Any help would be greatly appreciated before I go to the expense of replacing the carbs altogether and starting anew.

thanks in advance John
 

·
Registered
Joined
·
2,168 Posts
Very classic 'lean' situation. (1) Remember that some of these bikes used richer needles for the inner two carbs, and leaner for the outside ones. If you made the mistake (like I did) of taking all the carbs apart at the same time, instead of individually, you may have mixed up the needles. (2) Did you check the relative heights of the slide springs? This is a common problem, as well. if you squashed one or two of them shorter than the others. (3) Also, check to make sure all your vacuum lines are hooked up and routed correctly....(4) and finally,you might find that your fuel tank somehow has lost its venting. This will mimic a lean condition, but the reality is that the bike is starving for fuel at high rpms. Good luck.


DW
 

·
Registered
Joined
·
683 Posts
like mentioned above, check for vacuum leaks. a quick test that i've used before is to spray a little carb cleaner where leaks might occur. if this causes the engine to race a little, you've found your leak. also check other things like airbox leaks spark plugs. good luck.
t
 

·
Registered
Joined
·
54 Posts
a friend a simular problem it was his fuel supply couldnt keep up when he cracked the throttle open it would suck all the fuel from the filter he fixed this
by removing his pod filters and replacing the air box and the rubber gaskets around the lid
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #6 ·
thanks everyone. I did replace the labrynth on the gas cap as I noticed pressure building quickly as I rode. This seemed to help the tank pressure problem as it is non existent now but has not helped the stumbling. My thinking seems to be somewhat on track with the bike starving and as I rode today was thinking my float heights werent high enough although I am sure I am within spec. Also, when I disassembled the carbs the pilot screws were 2.5 turns out which is more than I read in spec as it called for 2 turns. I know pilot system is low speed so I dont imagine these settings are dramatically affecting the bike at higher rpm but thought I should mention. I didnt know, nor did I check to be certain of needles being the same nor relative heights of the diaphragm springs but I will check these items off over the next few days and get back. Also will spray a little carb cleaner around and see what happens. Stumbling really bad on steep hills, in high gear, wife and I, at about 60 mph. Some long pulls I even have to downshift, and thats unheard of with a big Z!!! Also, hard acceleration above 4000 rpm is non existent and bike immediately begins rumblin, bumblin, stumblin. Will hold its own up to about 65 then falls away. I will check back with results over next couple days if I can. My son is in the middle of his qualifiers for Loretta Lynns MX and I will be busy with bike prep and traveling out next couple weekends. Will Keep you all posted and thanks a ton for the ideas. If anyone comes up with anything else please post. Thanks John
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #7 ·
thanks everyone. I did replace the labrynth on the gas cap as I noticed pressure building quickly as I rode. This seemed to help the tank pressure problem as it is non existent now but has not helped the stumbling. My thinking seems to be somewhat on track with the bike starving and as I rode today was thinking my float heights werent high enough although I am sure I am within spec. Also, when I disassembled the carbs the pilot screws were 2.5 turns out which is more than I read in spec as it called for 2 turns. I know pilot system is low speed so I dont imagine these settings are dramatically affecting the bike at higher rpm but thought I should mention. I didnt know, nor did I check to be certain of needles being the same nor relative heights of the diaphragm springs but I will check these items off over the next few days and get back. Also will spray a little carb cleaner around and see what happens. Stumbling really bad on steep hills, in high gear, wife and I, at about 60 mph. Some long pulls I even have to downshift, and thats unheard of with a big Z!!! Also, hard acceleration above 4000 rpm is non existent and bike immediately begins rumblin, bumblin, stumblin. Will hold its own up to about 65 then falls away. I will check back with results over next couple days if I can. My son is in the middle of his qualifiers for Loretta Lynns MX and I will be busy with bike prep and traveling out next couple weekends. Will Keep you all posted and thanks a ton for the ideas. If anyone comes up with anything else please post. Thanks John
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #8 ·
thanks everyone. I did replace the labrynth on the gas cap as I noticed pressure building quickly as I rode. This seemed to help the tank pressure problem as it is non existent now but has not helped the stumbling. My thinking seems to be somewhat on track with the bike starving and as I rode today was thinking my float heights werent high enough although I am sure I am within spec. Also, when I disassembled the carbs the pilot screws were 2.5 turns out which is more than I read in spec as it called for 2 turns. I know pilot system is low speed so I dont imagine these settings are dramatically affecting the bike at higher rpm but thought I should mention. I didnt know, nor did I check to be certain of needles being the same nor relative heights of the diaphragm springs but I will check these items off over the next few days and get back. Also will spray a little carb cleaner around and see what happens. Stumbling really bad on steep hills, in high gear, wife and I, at about 60 mph. Some long pulls I even have to downshift, and thats unheard of with a big Z!!! Also, hard acceleration above 4000 rpm is non existent and bike immediately begins rumblin, bumblin, stumblin. Will hold its own up to about 65 then falls away. I will check back with results over next couple days if I can. My son is in the middle of his qualifiers for Loretta Lynns MX and I will be busy with bike prep and traveling out next couple weekends. Will Keep you all posted and thanks a ton for the ideas. If anyone comes up with anything else please post. Thanks John
 

·
Registered
Joined
·
683 Posts
you can say that again ...
 

·
Registered
Joined
·
990 Posts
Have you removed the spark plugs & checked the colour of them to see if that gives any clues as to what is going on?

I would tend to put a new set in anyway unless they are fairly new & you know they are all firing okay.

Also checked valve clearances prior to balancing?

If the fuelling seems okay I would start checking the ignition system through.
 

·
Registered
Joined
·
368 Posts
Has anyone mentioned replacing the fuel filter?
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #14 ·
Quick update, checked slide needles and found that i didnt re install them on the correct carbs on the correct cylinders, same for the mains. After reading your earlier posts I checked these otherwise I would never have thought to actually look at the manual and see it used different needles and mains for #1 and #4. I didnt realize you were actually suppose to READ the manual!!
I am sure I need to re synch them but havent done this yet. Bike seems better but still bitchy at 5000rpm and up. I have not checked for vaccum leaks around intakes yet and will do that with synch job. Fuel filter is new. Plugs are 4000 miles old. Air box is all stock, complete and correctly assembled so all should be good there. I am still really thinking float levels are low. What do you think.

thanks for the help
john
 
1 - 14 of 14 Posts
Top