'99 ZRX Hesitates and bucks through Midrange
 

Hi All,
I am new to this Forum. Not at all new to bikes. I do all of my own repair/ maint. work. I have been mostly dirt oriented. Have owned a string of KX 500s that I competed with in East Coast Enduros. I have been out of the bike scene since 2002 when I started racing boats. I just picked up a '99 ZRX 1100. After spending all of my cash on the boat, I could not afford a new bike. Anyway it is hesitating and bucking through the midrange. That is when I roll hard into the throttle. If I let it climb slowly it is somewhat smooth all the way till it comes on the cams then it goes to redline with with a vengance. I spent all afternoon yesterday cleaning out the carbs. #2 pilot jet was clogged. But that is all that I found that could be wrong with the carbs. Of course I haven't been into a CV carb in many years. But I am no mechanical slouch! It didn't make any difference in the performance at all! I hate throwing parts at anything, so I am asking for guidance on where to go next.
Thanks,
Mitch

RE: '99 ZRX Hesitates and bucks through Midrange
 

Was it rejetted?Too large ajet sizewould be my guess. Good luck let us know what you find.

RE: '99 ZRX Hesitates and bucks through Midrange
 

Welcome to KF Mad Mitch!

Sounds like you have a good grasp of carb tuning. You prolly checked the plugs as well already. The only difference now is that you have a rack of 4 carbs and not just one. If you are positive that all 4 carbs are clean, what is the carb synch tell you? ie, making all 4 carbs working together in synch on your vacuum gauge.

RE: '99 ZRX Hesitates and bucks through Midrange
 

Thanks for the response. I have not synched the carbs. I don't have a mercury stick set up but have a buddy that does. Will do thatas soon as I can get him to help me.I did not change anything that would change the sync. The jetting is a little on the lean side as the plugs are a light grey color. Not way lean white, but certainly not rich. One thing that I did do is leave the KTRICK sensor unplugged. It ran exactly the same. Could it be bad? I will ohm it out tomorrow. It is a throttle position sensor right? Possible that it is affecting spark advance?
Gotta go wife is calling for dinner.
Mitch

RE: '99 ZRX Hesitates and bucks through Midrange
 

But you removed the rack to clean the carbs. And while the rack was out, you visually inspected all vacuum lines of course.

edit: Get to dinner, don't want to piss mama off any.

RE: '99 ZRX Hesitates and bucks through Midrange
 

Make sure the airbox ( if you have one still ) lid is on tightly. Sometimes they can put back on and not lined up right.

If you have pods, clean them and re-oil. Could be making it run rich.

Also make sure the vacuum hose is hooked up to the carbs. But then again, you would run out of gas if the hose was off.

RE: '99 ZRX Hesitates and bucks through Midrange
 

Yes I visually checked out all lines. But did not take them apart for a vacume test. Probably should have, duh! I didn't take the rack apart, just pulled each bowl, jets, float and needle assys, one at a time. Blew out all orifices with compressed air. Then took tops off, one at a timeinspected all diaphrams. Blew everything clean. Like I said before though, it has been a real long time since I have been in a CV carb. I will pull them again when My buddy shows up with his sticks and a little more CV knowledge. Probably this weekend. You guys think I should focus on the carbs, I will do it more thoroughly next time. I been messin with holly double pumpers a little to long! He He!
Thanks,
Mitch
Damn good steak dinner by the way!

RE: '99 ZRX Hesitates and bucks through Midrange
 

From what you mentioned, you are a competent mech so far as the carbs go. It will come back to you. You know your stuff, so get it done.

RE: '99 ZRX Hesitates and bucks through Midrange
 

My bike was doing something similar. Adjusting the float hight seams to have helped.

RE: '99 ZRX Hesitates and bucks through Midrange
 

drag beat me to the sync thing..lol

yup. check vacuum piston actuation and seal.. make sure the springs are seated and in one piece, and that the o-ring itn the cap, and the diaphragm are not gunked up or torn..

also check which notch the vac. piston needles are on, as well as float height, and boot tightness..

if the carbs were tinkered with prior to your acquisition, chances are jetting could be jacked up, sync is out..

process of elimination bro.. the CV's are cake.. if you work on the holleys all day.. then these little carbs are a dream. very simple..

and welcome to KF!! :D