High revs

[stug]

Just put the rest of the bike back together and wanted to balance the carbs.

What a nightmare!! Whos clever idea at Kawa's was it to put the adjuster screws at the top of the carbs so you have to take off the airbox to adjust them.

Apart from that the bike has now developed a small problem which I need a bit of advice.
When the bike is running its fine but after giving it a blip on the throttle, it takes its time to fall back to tickover.

I was thinking this is possibly air being taken in around the carb inlets which needs sealed.

Does anybody have any other ideas or could that be the answer?

[jack sharpezxr 400 L]

throttle cable ???

[stug]

no, the throttle is returning as normal, you can see it from the side, but after the throttle goes back to the stop the revs slowly drop instead of instantly.
The choke cable is fine also

[masterofinsanity]

usually air intake around the inlets as you have already sussed.

[stug]

Is it normal on these to have to put a smear of instant gasket around the inlet before bolting it on?

[masterofinsanity]

personally i would, i'm sure the heat from the head will warp the rubbers over time.

[stug]

Sorted out the rubber inlets by sealing them up.
Checked diaphrams again and all is fine there, no sticking slides.

The problem now seems different and I will try to decribe what is happening.

When the bike is started for the first time it seems ok, running on 4 cylinders.
After a minute it will struggle to idle and seems to run on 2/3 cylinders then if you stop revving it it will cut out.
After draining the float bowls and starting it is fine again and running smooth on 4 cylinders but again after a minute it seems to lose power and either jump onto 2/3 cylinders and wants to die.

I am now thinking of the float/fuel heights being wrong.
Does this sound like symptoms of this?
I have never had to mess around with these before.

[masterofinsanity]

are you getting sparks from all 4 cylinders?

[stug]

Yea getting sparks ok.
I have been methodically going through everything I have done and I think it is possibly the air feeds for balancing the carbs as that seemed to be the last thing I done before it went wrong.
The pipes are not really a tight fit so are possibly letting air in.

[markzxr400l3]

Hanging revs are normally a sign of lean mixture or leak of air on the inlet. Did you actually balance the carbs or not. Theory... if the bike was running with an iffy idle mixture and imbalanced carbs you may have balanced the carbs but on the wrong pilot mixture settings which could cause the symptoms you seem to be describing. Just a hunch but what about checking the idle mixture screws are 2 and a quarter/half (ish) turns out? ** this is assuming standard carbs, cams etc etc.

I battled something similar for ages and turned out to be two problems making diagnosis a nightmare. My cure was new plugs and very careful fettling of the idle circuit and balancing. (mind you i've got zx4 cams in so it was a bit hit and miss).

Good Luck mate

[stug]

It seems to be sorted now.
A small thread from a rag was in the fuel filter under the float valve.
This was causing one of the carbs to overflow slightly.
Air screw on an L2 is 1 and 3/4 turns out as far as the manual says.
Carbs are pretty much balanced as close as I can get, its a pity you have to do it with the airbox off.

[stug]

I seem to have spoken too soon.
The revs although are better, they are still not returning to tickover straight away.

Next on the list is the o-rings that go around the float valve filter holder thing.

These did not seem very tight when refitting, could this be the cause of my problem??

[RedexRobB]

Id say new inlet rubbers mate,

[stug]

If the inlet rubbers look ok with no splits / cracks in them and there is no leaks around them , Why should I change them??

[jake]

just get that idle screw richened up mate.
The manual may say 1 and a bit turns... mine is on 3 turns out. even my standardish engine was just about 3 turns out too.