Revs dropping slowly

[fq-craigus]

Hey people, still getting the zx6r sorted and aside from wheel bearings to do I have a problem with the carbs.

I took them off today and gave a clean due to running poor at low revs and also the revs dropping slowly.

So I had them off, float bowls off, pilot jets cleaned, pilot screws cleaned, main jet cleaned then back together.

When it started it ran better low down revs but the revs are still hanging.

I have sprayed carb cleaner round all the boots and vac lines and the revs don't pick up at all so I have ruled out vac leak but what other reasons could there be?

Any advice would be appreciated,

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[Stu]

hanging revs is usually a sign of an air leak

try spraying some WD40 around the carbs when its doing it and if it bogs you are getting close

[Mr Fro]

Hanging as in takes a while to settle back to idle after a rev?

Like Stu says - that'll be a lean condition like an air leak or a screw out if adjustment.

[fq-craigus]

Hanging as in you rev the throttle and it revs to 5k for example, stays there then slowly falls to idle again.

The mixture screw is the only screw I messed with and I put that back to 3 turns out.

So wd40 will make it bog down will it?

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[megawatt]

If there's an air leak via the inlet rubbers, the WD will be sucked in by the vacuum and the engine will try to burn it.

[fq-craigus]

I have just been racking my brain and trying to work out what I did before it started hanging revs.

I remembered I tried the cheat and put wynns fuel system cleaner in the fuel day before yesterday. After I let it cool down completely then started it up is when it started hanging the revs. Do you think this has leaned out the fuel, maybe diluting it down?

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[Mr Fro]

I have just been racking my brain and trying to work out what I did before it started hanging revs.

I remembered I tried the cheat and put wynns fuel system cleaner in the fuel day before yesterday. After I let it cool down completely then started it up is when it started hanging the revs. Do you think this has leaned out the fuel, maybe diluting it down?

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How much did you stick in? I doubt it'd make much difference as it's naptha based.

[fq-craigus]

The mixing was 325ml to at least 20 litre fuel so I used approx 250ml for about 17 litre

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[Hoggs]

just a small note... is the throttle snapping back off ok? mine sticks a bit so just thought I'd mention it

[fastbob]

If there's an air leak via the inlet rubbers, the WD will be sucked in by the vacuum and the engine will try to burn it.

 

Correct me if I'm wrong but I thought you detected air leaks by spraying Easy Start and if the revs go UP then there is an air leak .

[fastbob]

I'm not sure about your particular carbs but is it possible that when you replaced the tops you either dislodged or forgot to replace the tiny little O rings that go around the vacuum gauge take off points ? It's easily done because they can stick to the carb tops and then fall off when you're handling them . The O ring is missing in this picture but you can see where it goes. I just happen to have a Mikuni carb as an ornament .

[fq-craigus]

I didn't remove the vaccume chamber on top.

The throttle is snapping back nicely too.

Had a small development, I'm hardly getting any time on it at the min but I'm waiting for some balance gauges but I crudely synced the carbs with a small drill bit then adjusted mixture screws and got the bike running almost sweet. Should have the gauges within the next few days then I can do it properly

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[TimR]

Have you sync 'd the carbs after the rebuild ?

You have disturbed lots of things which may have been sync'd to the problems before .

Doh missed the previous post ..