Kawasaki Zephyr 550 will only start with choke

[garacs]

Sparkplug cylinder 3
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Working on it: Kawasaki Zephyr 550B 1991

[garacs]

Spark plug cylinder 4
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Working on it: Kawasaki Zephyr 550B 1991

[garacs]

A picture with all the spark plugs together, left to right 1-2-3-4
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Working on it: Kawasaki Zephyr 550B 1991

[garacs]

Short videos of the sparks on each spark plug.

Cylinder 1:
https://www.youtube.com/shorts/OOXj97Bo4jQ

Cylinder 2:
https://www.youtube.com/shorts/mjYDHAfyGMM

Cylinder 3:
https://youtube.com/shorts/03Mp2TCKjI8

Cylinder 4:
https://youtube.com/shorts/RyG66Jt7IxY
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Working on it: Kawasaki Zephyr 550B 1991

[jaffa90]

I expected to see some slight light brownish carbon, 2/3/4 are running with a very weak mixture. If you have no unwanted air going in then i suggest low fuel levels.
https://www.bikechatforums.com/google.php?q=setting+floats+on+a+550+kawasaki+zephyr

[garacs]

[garacs]

I checked the floaters with a caliper for the float height directly, and they are all set to 16mm
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Working on it: Kawasaki Zephyr 550B 1991

[garacs]

I will then try to check with the transparent tube method instead, since that's actally the only way to see if the carbs are full of gas or not.... never did this before, since when unscrewing the drains screw I always noticed gas coming out, so never really bothered to check the level inside the bowls
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Working on it: Kawasaki Zephyr 550B 1991

[Nobby the Bastard]

I disagree, The 3 look fine (a light tan colour) but no.1 looks like it's overfueled.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[garacs]

[jaffa90]

On an air cooled engine you cannot afford to run it on a lean mixture.

If i set float heights on sprung loaded needle valves ( single carb) i attached a pipe to the fuel inlet and blow then raise the float until it stops me blowing.
Or your method with the clear pipe.

[jaffa90]

A long shot, does the fuel tap have a PRI position?

[garacs]

[struan80]

Just out of ineterst from someone with no clue or real interest motorcycle mechanics.

Does the fuel system not need to be vented from a high point?

And to show my ignorance does the bike have a fuel pump or gravity fed. From the sketches I assume gravity fed.

I'm trying to learn.

[garacs]

[jaffa90]

[garacs]

[Nobby the Bastard]

PRI works when you have a vacuum controlled tap, where the tap doesn't open unless there is a vacuum on the vacuum pipe to the tap.

It stands for PRIme.

If it's that sort of tap then ON only allows fuel to flow to the carbs when the engine is running (so there is a vacuum caused by the intake.)
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[garacs]

[jaffa90]

"""" I use it to empty the tank easily and fast. """

A fuel tap does not empty a tank but if you have a clear inline fuel filter fitted you should see if any crap is coming out of the tank.

( you may have fitted one ?)

[garacs]

[garacs]

Investigating.... I removed the carbs once again. They are SPOTLESS! Though I did find something strange. I had bought months ago in preparation of the rebuild a new carb kit off ebay.

Well apparently one of the pilot jets was shorter.

So.... they are 28.66mm / 28.70mm / 28.64mm for carbs 4/2/1 respectively in length.... carb 3 is 28.14mm. Even the spring on that one is shorter.

They got probably mixed up. I still have the old ones, which were a bit oxidised and "worn", but at least all the same length, which range from 28.54mm to 28.56mm.

So I reinstalled the old ones, at least with them the difference in lenght is less than 0,02mm. I installed them with new o-rings, of course.
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Working on it: Kawasaki Zephyr 550B 1991

[garacs]

Now was the time with the floaters. Sinc the plungers came in the same kit of the idle screws, I wondered if there was a difference also with them, which luckily there was none.

Yet, the floaters were all, again, at different hights. So I set them up again, and now even if everything seems to be set properly, carb 3 leaks fuel.

Have to check the floaters again, I suppose...
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Working on it: Kawasaki Zephyr 550B 1991

[garacs]

So I am remounting the carbs, upside down, and rechecking also the jets. Wish me luck...
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Working on it: Kawasaki Zephyr 550B 1991

[garacs]

So after a lot of fiddling, carb 2 is leaking from the 2 holes on the air intake port. Carb 4 is barely leaking from the same spot as well...

Ideas?
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Working on it: Kawasaki Zephyr 550B 1991