Z1000 MK2 - Poor running in the 2-3000 rpm range

[njwmct]

have you checked the slide heights?

Yes - did that yesterday.
Followed the Kawasaki Manual.
Set gap between Pulley Stopper & Cable Bracket at 1.8mm
Then set clearance at bottom of slides to 0.7mm

Is this the correct method?

[njwmct]

Following on from setting the slide heights.
Put the vacuum gauges on to fine tune the balance (which wasn't far out anyway) & got them spot on.

Took the bike for a spin & the revs were still hanging a bit.
Gave it a bit of stick up to 6000 rpm & then the revs started hanging for a lot longer at up to 3000 rpm.

Somethings obviously not right but buggered if I know what

[z1bman]

copied from steve smethurst

Won’t shut down 1:
Slide height of 0.70mm is critical, to high and the engine is slow to shut down. Prove by removing the tick over screw. Should rev and shut down in the desired manner

.
Won’t shut down 2:
Caused by a long spark particularly when using new spark plugs. The plug insulation has broken down and the spark plug voltage is jumping a greater distance to earth. Weak spark changes ignition and combustion characteristics.

[Al]

As above, also i believe this was part of the problem when you first bought / commissioned the bike.
Needle jets.
Myself, i would raise the needle / lower the circlip one more notch to;
a rule out a weak mixture
b offset the effect of the Harris.

If the needles are standard and matched to the needle jets you have fitted then; b.

Nothing to loose and whilst i was there i would take a look at the return springs on the throttles. Only used to J ones which have individual per carb but have got them wrong with similar results.

Assuming all else is well, how do the plugs look / piston crowns / and rear of tailpipe for combustion products?

AL

[njwmct]

Thanks for the replies chaps:

Z1B Man,
I'll give the bike a run today with the idle screw right out/no idle to see if the revs still hang.
If I can get hold of a new set of plugs I'll try that to.

Al,
The original problem when I first got the bike was a needle jet with a corroded bore on carb no. 1 making it too rich at idle & causing a stutter just of idle - a replacement second hand needle jet solved the issue.

Not sure what's going on now but the new needle jets are Mikuni 258 O-1 as per the originals that Allens Performance got from Japan.
When I removed the original needle jets, inspection showed thsat they were all showing signs of pitting to their internal bores.

Std needle clip position is 3 form the top - currently on position 4 - I guess you are right that I could go to position 5 to see what happens.
Interesting that I didn't have the revs hanging when the clip was on no.3 but of course I had a misfire at 2-3000 pm & surging on a constant 3000 rpm throttle.

Oh yes the needles are standard & in good condition with no visible wear or scoring.

[njwmct]

OK - wound the idle speed adjuster right out & took it for a spin.
The revs didn't hang at all.
If you close the throttle then the engine cuts out.

If you adjust the screw back up so that it idles at 1000 rpm then when you rev it, it starts to hang again.

So a little confused now, as if this means that the problem is slide height then how do I sort it as they have been set as per the manual at 0.7mm?

Also fitted a new set of plugs but that hasn't changed anything.

Also messed around with the pilot screw setting & found that the revs hang more as you turn the air screw out - suggesting that a weak mixture is the cause - but again a little confused as to why raising the needle would have caused this condition in the 1st place?

Going in lessened the effect but the idle became very lumpy as I guess it was too rich at 1/2 turn out from fully in.

[njwmct]

Check pilot jets again - may need to return needle clip but go up 1 x size on pilots

Pigford going to try your suggestion next.
A set of 17.5 pilot jets arrived today from Allens Performance - std is 15
Will try these with the needle clip back on groove 3 (std)

(Allens also sent me some needle shims which allow movement of the needle equivalent to a 1/2 groove)

[z1bman]

i would try lowering the slide height to 0.6 mm & make sure you are measuring from the top of the slot in the bottom of the slide ?

[njwmct]

i would try lowering the slide height to 0.6 mm & make sure you are measuring from the top of the slot in the bottom of the slide ?

OK will give it a go.
& yes measuring from the top of the slot in the bottom of the slide.
(what confuses me is that surely as idle speed is adjusted to spec then surely the slide height increases anyway?)

[njwmct]

OK - Had the carbs off again today.
Set the slide heights very carefully to 0.6 mm - but the revs are still hanging / slow to shutdown.

Then I changed the pilot jets up one size from #15 to #17.5 - this immediately improved the idle - much smoother - but the revs are still hanging.

Next step going to try dropping the needle back to position 3

[njwmct]

OK - Had the carbs off again today.
Set the slide heights very carefully to 0.6 mm - but the revs are still hanging / slow to shutdown.

Then I changed the pilot jets up one size from #15 to #17.5 - this immediately improved the idle - much smoother - but the revs are still hanging.

Next step going to try dropping the needle back to position 3

[Pigford]

You sure your cam timing is correct - and the cams are standard

[njwmct]

You sure your cam timing is correct - and the cams are standard

Standard cams - set up / timed as the day it left the factory.

[zed1015]

Make sure you have some slack in the throttle cables (especially the return)
Having them too tight will cause the symptoms you describe.

[Z1Boy]

I'm having this issue, one day bike running fine after the rebuild, next day, revs hanging. Been following suggestions in this thread and tried most things. Had carbs off, set slides with 0.7mm wire as close as possible following Hymers manual, set float heights with tube gauge. fitted new inlet rubbers. I'm pretty sure I've eliminated any carb problem.
Tomorrow, I'll check valve timing and fit new plugs. If that don't work, its going on ebay.