Fueling issue (?) with '01 ZX6R

[Cath]

Hi guys.
I'd really appreciate any suggestions any of you have.

I have an '01 ZX6R (so no injectors) that is having a fueling issue.
The bike surges when held on constant throttle. It also 'misses' or 'delays' when I crank open the throttle sharp-ishly.

I have run some fuel cleaner through it, and been picky about where I source fuel from, but that hasn't made any difference.

Dave and I will be pulling it apart this weekend to try to fix it - ok, to be honest, Dave will be pulling it apart while I look over his shoulder and learn (and fetch cold drinks!).
All the plugs have been out and are all slightly lean to the same degree (so it definitely isn't flooding as we first thought) but they aren't anywhere near too lean - she's always run on '98 octane. The ram air tube is connected and undamaged. The air filter is new. The problem is only really apparent when under load - the engine revs smoothly when in neutral and the problem can't be detected.
Ty has suggested checking for leaky vaccuum hoses as one possible problem.
Any other suggestions on what to check while we've got my baby in pieces would be gratefully appreciated!

[Neilp]

Sounds like it might be electrical to me, have you checked for a good clean spark?

Neil

[Barrabob]

put it in a pm but look at the spigots that are used for carby balance and see if there all still there and check the boots that conect the carbies to the head to see if there are any cracks or sucking air thru there.

carby pull down after that are all the slides working as they should inside the carbys could try a bit of sray while it is running but pulling the carby block to bits on the kitchen table is more fun.

aghh it takes me back....dont squirt any carby cleaner in your eye.lol

[matchan]

....

aghh it takes me back....dont squirt any carby cleaner in your eye.lol

Mate, words to live by !!

[RG]

Try this simple method taught to me by someone who is very experience.

Fuel cap, yes the whole fuel cap assembly, remove it(allen keys) and put it back on again. Sometimes it's just the rubber seals around it that is causing the problem.

[Slow and wobbly]

Why do you believe it to be a fueling issue?
Troubleshooting is all about the details. firstly how many kays has it got? when was it last serviced? when did you first notice the problem? was it a sudden development or did appear over time? is it ridden regularly ie. daily or is it a weekend / occasional bike? does it appear consistantly or do the effects vary from day to day? where in the rev range does it appear and will the bike rev right out? Has anything been changed recently?

simple checks-
1 as above check for strong spark
2 ensure air filter and airbox are sound and appear as they should.
3 before you remove the carb bank open the drains on the bowls and check for discoloration or bits of crap etc

[Cath]

firstly how many kays has it got?
About 47 000

when was it last serviced?
Funny you should mention that - two weeks ago

when did you first notice the problem?
I first noticed it when I picked the bike up from the service - she was slightly overdue for her 45 000 service. I took it back to them and they did another full service, since the mechanic couldn't feel the problem. The second full service did nothing - problem still exists. I was surprised that the mechanic couldn't feel the problem, but later learned he's strong with dirt bikes, not road bikes. Since he's already done another full service and can't find the problem I'm talking about, I do not have any confidence in taking the bike back there. If Dave and I can't figure something out we will take it somewhere we've heard good things about - at the moment I'm unemployed though, so we will try ourselves first.

was it a sudden development or did appear over time?
This is a tricky one. For the purposes of diagnosis, it may be better to go with 'unknown' for this one.
Embarrassing longer version: I was a total idiot about this and have now muddled the issue. It was a sudden issue, in that it was really noticeable when I picked the bike up after the service. On the other hand, I've always thought that the delay from when I open the throttle to when the power comes on was longer than I'd expect - but that's pretty much the only 600 I've ridden, so no comparison. And I can't travel back in time now and confirm whether my impression of the bike running a little rough and needing a service asap (remember - overdue for a service and unemployed so I was trying to find the money to service her) could've been this problem, i.e, was the 'running rough' the same as the current problem and I didn't look into it too hard, figuring that the service would fix it - so I'm not 100% sure if it started before the service or not. I was also full of self-doubt about the problem after the service - compounded by the fact that the mechanic couldn't find / feel the surging I was talking about, at all. I even thought for a while that it was in my head or I was being too picky and making a big deal out of nothing - after all a mechanic should have a better clue than me! I'm embarrassed about that self-doubt and won't do that again - I ride the bike enough that if something is wrong, *I* should feel the change before anyone else will, not defer to mechanics. Lesson learned on that score.

is it ridden regularly ie. daily or is it a weekend / occasional bike?
Every weekend, without fail and usually two or three times mid-week

does it appear consistantly or do the effects vary from day to day?
Consistently, though it's noticeability depends on how it's being ridden.

where in the rev range does it appear and will the bike rev right out?
It is most noticeable at around 7000 in top gear, but I can't be sure it isn't also happening at other revs. It is hard to feel it happening on rough/shitty roads - something the Central Coast has plenty of - so testing for the problem is a bit tricky, involving a 20 minute ride, not a quick test around the block. It possibly appears to be more noticeable when the engine is warm (hence originally thought it might be running too rich) but not 100% sure on that. It is the most noticeable when under powered i.e, riding sedately in a gear or two higher than when having fun. What do you mean by "rev right out?

Has anything been changed recently?
You sound like my db admin "Has anything changed recently?" = "What the hell did you do to it / install on it?"
Nothing changed at all. Just before the service I put fuel in from a place I hadn't used before - which is why I tried fuel cleaner and two full tanks of fuel from a good place before turning to other causes.

[Slow and wobbly]

More questions-
on the last service did they check valve clearances?
if so did they alter them?
does it idle smoothly? doesn't hunt around?

[BladeBoy]

Cath, Dave,

As your bike has been serviced I would suggest that the plugs have been replaced and you say that the plugs look a little lean, then I doubt it would be an electrical problem if it was the plugs would be "wet" from unburnt fuel, you say your air cleaner is OK this again I would doubt is your problem as it would be crap all through the rev range and not stutter at one point, as posted before make sure the blanking plugs on the carb balance tubes are still there or not cracked, as I posted before I bet the carb sync is out and I have the gear to check this if you want it, IMHO I would be up the guy who " SERVICED " it in the first place it does not matter, you have paid him/her to "FIX" it and that is just what they should do.
If you want I can drop around, two heads are better that one( one old one)
Cheers,
Mark.

[MadKaw]

Yep, plenty of food for thought above..

Also check the clean air intakes into the carb from the ram air and the fuel on/off switch in the tank for any minor blockages or vacumn problems...

[Slow and wobbly]

carb synchronisation would cause the bike to idle roughly / hunt around and the problem would be previlant throught the rev range. It never hurts to check the synchronisation but I am doubtful that this is the problem.

[Slow and wobbly]

By rev out I mean does it get to the top end of the rev range without detiorating, lurching or missing the higher the revs get.

Is the temp guage reading normal or is it higher than normal? It might be hard to tell with the warmer weather and all but go out early morning and see if sits at its normal operating temp.

[icebreaker]

check the fuel line... could be pinched..

they might have not put the tank back on right..

[BladeBoy]

carb synchronisation would cause the bike to idle roughly / hunt around and the problem would be previlant throught the rev range. It never hurts to check the synchronisation but I am doubtful that this is the problem.

I had a ZXR with the same problem, flat spots but idled OK, was a balance problem, thats why I bought the balancer, 10 minute job and it was good as gold, it to had just had a service at Rick Andrews and it run like shit, I took it back and they gave me all the reasons under the sun why they could not fix it, worn slides yadda yadda........fixed it myself, never go back, the difference with Cath's problem is her bike is not that old and at 43,000 Klms nothing should be worn that bad, I don't think they have any reason not to fix it, I can not believe the mechanic could not "feel" the problem. next time pay them by cheque and cancel the bastard if the job is not done right, that will get their attention.

[I-K]

carb synchronisation would cause the bike to idle roughly / hunt around and the problem would be previlant throught the rev range. It never hurts to check the synchronisation but I am doubtful that this is the problem.

Note, however, that the guy who serviced the bike is dirtbike specialist. I wouldn't be surprised if balancing the carbs just slipped off his checklist.