'98 ZX-7R idle response problems...

[J Banning]

This seems to be a pretty active forum, and this is my first post here, hopefully someone here can help me out.

I just recently bought a 1998 ZX-7R from a friend of mine. The bike only has 2,700mi on it, but it sat in his garage for the last couple of years with fuel in it. Initially the bike would only idle with the choke on, and even then only at 1,400rpm. I drained all the fuel out of the tank and pulled the carburetors off and cleaned them with much better results... BUT it still isn't perfect. The bike is rideable now, but still somewhat hesitant to start quickly, and off idle throttle response is poor.

When I pulled the carbs I did the following:
- Pulled the vacuum valve and plastic cover/cap off the top of the carb.
- Soaked each carb in diesel over night, followed by blowing carb cleaner and compressed air though each passage the next day
- Removed the float bowl & cleaned the junk out of the bottom.
- Removed the jets & cleaned with carb cleaner & compressed air.

Notes:
a) I did NOT change any settings, and as far as I know nothing has ever been adjusted on this bike. There was still factory paint applied to each of the throttle adjustment screws/springs. I reassembled everything just as I took it off.
b) Everyting is stock except for a D&D slipon muffler.
c) I have a Clymer shop manual for the bike.

Like I said, the bike actually runs now, but it isn't perfect.

I currently have two problems with the bike:
1) Cold start: Bike hesitant to start, and initially the idle is low.
2) Off idle response: Response is slow, and on the road, engine RPMs jump between gears.

Problem 1:
a) When the bike is cold, I use the choke and it takes several tries for the bike to start.
b) When the bike finally starts it initially idles at about 1,000rpm, slowly climbing to about 2,000rpm after about a minute or two. Shouldn't it be about 2,500 from the get-go??

Problem 2:
a) Once warmed up and idling (about 1,100rpm), if I quickly blip the throttle it either wants to stall or it is very slow to respond. By slow I mean that by the time I let off the throttle the RPMs just then begin to climb. This isn't so bad at higher RPMs (ex: blip the throttle at 4,000rpm).
b) When riding the bike, I let off the throttle and pull in the clutch to shift gears and the RPMs climb another 700-1,000rpm.


I'd really appreciate any suggestions. I'm one step away from giving in and taking it to a bike shop.

Thanks,
-Banning Cohen.

[WeBeToyz]

I would seriously consider sync'ng up the carbs. Your idle mixture may be out of wack due to incorrect Pilot air screw settings. Do you know if any adjustments were ever made when the slip-on was added?

Did you pull & clean the Pilot jets/passages and if so what were the number of turns out? Baseline for the Pilot air screw is 2 1/4 turns.

You could also have a vacuum leak, and I have also experienced worn carb slides for this problem but I wouldn't think that would be the case given the miles on the motor...

[J Banning]

Thanks for the feedback Bryan.

I touched everything but the pilot air screw settings. Why, I'm not really sure, perhaps because I knew it was more sensative than the other components. Regardless, I know what I need to do now!

I think I've pretty much ruled out the vacuum leak. I checked all the diaphragms (top of carbs) and no issues found. I also double checked all the lines, and sprayed everything with 2+2. Nothing found there either.

I'll post any results from tomorrow's garage session.

Thanks again.
-Banning.

[evmo]

Just curious, how many miles have you ridden the bike since you got it running?

[alb4099]

Go over everything again specially the jetting part, I had the same problem till I took her to the shop and the guy said one of the jetts was almost out. He cleaned the carbs,jets and sync them and now runs perfect !!!!!! my bike also sat for a while before I bought her..........

[J Banning]

60 miles.

[J Banning]

84 miles now.

I spent the afternoon/evening pulling the carbs again. I pulled all the jets (including the idle circuits), ran carb cleaner and compressed air through everything, and put it all back together.

How's it run??

There's no change in performance (DOH!!)

I still have the lazy throttle response off idle and the over-rev between gears. It is rideable, but not as much fund as it could be. I don't have much more time to mess with this over the next month, so I guess it is time to find someone to take it to.

-Banning.

[J Banning]

A couple of pictures of the carbs from today. Does everything look clean enough?

[WeBeToyz]

That one float needle looks like it might be pretty worn - refering to the dark ring I see where it would seat. Were the others like this as well? I really don't think this would be your problem, unless your float heights are way off (float heights here), but other than that the parts/carbs look pretty clean.

Did you happen to take note of what the pilot screw settings were - how many turns out?

[J Banning]

They didn't look worn, just a little dirty. I ran out of time with the bike (won't be abe to touch it for the next couple of weeks at the earliest) and ended up taking it to a local shop. I should know what's up in a couple of days.