Kawasaki Zephyr 550 will only start with choke

[garacs]

Hello everyone!
Being a newcomer first of all I would like to present myself: I am 51, living in Berlin, Germany, and recently bought a 1991 Kawasaki Zepyhr 550 to restore. I bought it cheap and worked on it in my spare time.

The bike was not running, it had been stored in a garage for some 5 years (as far as I know, maybe more) and was needing a full rebuild, so that's what I did.

I do have mechanical experience, having owned several bikes and scooters (2T and 4T) in the past, so I am not a complete newbie.

Yet, after replacing parts with original Kawasaki spare parts, following the service manual to the proverbial "T", when it ws time to attempt the first start, the engine turned happily, but I had no spark.

Investigating the issue, I nailed it to a defect CDI. Replaced that, sparks were finally there.

Now the moment of truth...

Turned key, ignition, on, choke, new fuel... it started! I let it run to 4k for some 7-10 seconds, then slowly turned the choke lever to the off position, and the engine died...

Choke on again, engine starts, leave the choke on and try to give some gas, very slowly... it died.

To make a long story short: it starts perfectly well with the choke on, but dies as soon as I give gas or turn the choke on.

Carbs were cleaned in ultrasound cleaner, part by part (disassembled the carbs before, obviouly). New Kawasaki original gasket sets installed, new floaters, all new basically. All installed according to the manual.

Yet I have no joy. I read all other posts in this forum with similar questions, and they all point to an air leak, which I believe to be the issue, but disassembling the carbs and reassembling them several times, I can never find the leak.

Here a small video of the issue:

https://youtube.com/shorts/EWkqf4piB_g

What am I missing?
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Working on it: Kawasaki Zephyr 550B 1991

[garacs]

Another small video

https://youtube.com/shorts/GSu4xObzNL0
____________________
Working on it: Kawasaki Zephyr 550B 1991

[blurredman]

You definitely didn't confuse the jet positioning, say accidentally putting the idle jet as a main and vice versa?
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CBT: 12/06/10, Theory: 22/09/10, Module 1: 09/11/10, Module 2: 19/01/11
Past: 1991 Honda CG125BR-J, 1992 (1980) Honda XL125S, 1996 Kawasaki GPZ500S, 1979 MZ TS150.
Current: 1973 MZ ES250/2 - 18k, 1979 Suzuki TS185ER - 10k, 1981 Honda CX500B - 91k, 1987 MZ ETZ250 (295cc) - 40k, 1989 MZ ETZ251 - 50k.

[garacs]

[garacs]

So I removed the carbs and reset to factory standard the idle screws...

Pilot screw setting (turns out): 2 1/4 turns out
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Working on it: Kawasaki Zephyr 550B 1991

[garacs]

[garacs]

[garacs]

Well I disassembld the carbs again, and checked the pilot jets - the were clogged from gunk from the old fuel I had used to test it out a couple of weeks ago.

Now it starts perfectly, does not bog down when giving gas, and finally holds the idle, as it should. Next steps: synchronization. Wish me luck!

https://youtube.com/shorts/PpDrTn5kTcE
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Working on it: Kawasaki Zephyr 550B 1991

[Easy-X]

Step 1: clean the carbs
Step 2: clean the carbs (properly this time)


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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[RhynoCZ]

It also sounds like you should have a look at the timing chain tension.
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[garacs]

[garacs]

[garacs]

aaaannndddd.... after a couple of days not working on it, I tried to start it, and id did only with the choke (we have 28°C today...). And I noticed that cylinder 1 does not start together with the others: it is "cold" until I rev the engine up to 5k, then finally starts and the idle settles. Yet it bogs a bit when I give some gas... but at least it does not die.
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Working on it: Kawasaki Zephyr 550B 1991

[Easy-X]

Wouldn't hurt to pull the plugs and see if you have a weak spark on that cylinder from cold
____________________
Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[that_impulse_guy]

no mention made of cleaning our all the gunk that will be in the petrol tank, the petrol tap etc.

and once done, put an inline fuel filter in....because at this rate youre going to become really good at taking the carbs on and off
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Gone: Yamaha DT50lc, Suzuki DR500, Suzuki A100, Kawasaki z250ltd, RD350YPVS, Suzuki DR Big, Kawasaki AR125, Kawasaki KMX200, Suzuki GS1000S, Katana 1100, GS550M, Suzuki RGV250
Now: Suzuki GSX400X, Suzuki RF900R, NS400R

[garacs]

[A100man]

[garacs]

[A100man]

[Robby]

It looks like every problem so far has been down to filth in the carbs.

I'm assuming cylinder 1 is on the left of the bike as you sit on it, so it is also the lowest point on the fuel system when the bike is on the side stand.

Water is heavier than petrol. It settles in the lowest point. Drain the carbs and look for water in what came out. It is likely that you have a puddle of rusty water sitting in the bottom of your fuel tank. Set the fuel tap to reserve to drain out most of it (preferably not into your carbs). Fit an inline fuel filter.

Expect this problem to continue to appear for ~1000 miles, until all of the crap and water in the fuel tank has been flushed through. Petrol with ethanol in will help to absorb the water.

Two main things that cause this problem:
1. Condensation. Fuel tanks breathe a bit. Moisture in the air gets into your fuel tank, condense on the walls of the tank, and drips down to sit under the fuel for the rest of time. Keeping the fuel tank full helps with this, as well as using it regularly. It's a problem on bikes that have sat in a shed for years.
2. Leaking fuel filler cap. Rain gets in.

[garacs]

[garacs]

[Robby]

An exhaust leak should not cause this issue. It can make the bike run slightly lean on that cylinder, but not enough to cause your problem. You should still fix it, but don't expect it to do anything.

The most obvious explanation for your problem is still something clogging up the number 1 carb. My reasoning is that you're not getting enough fuel through at low power requirements - so fuel isn't getting through the small holes. When you have the engine spinning faster and a higher power requirement, you are getting fuel into the engine through the bigger holes.

So I would be checking that carb, yet again. I would also be going through everything upstream of it - fuel line, carb fuel rail, filter, fuel tap, tank. Looking for any rust or gunk and cleaning it out.

If the tank has any sign of rust inside, I tend to treat them with phosphoric acid. A 4L bottle is cheap and does the job. Just don't get it on aluminium or rubber parts, unless you want them to dissolve.

[blurredman]

[sickpup]

Inlet manifolds and airbox manifolds are usually rock hard and cracked on these. Genuine new Kawasaki ones in my experience are also rock hard and cracked, its always the first thing I look at on these.

Also I seem to remember the inlet manifolds use a stupid spring retainer around the carbs instead of a clamp, they let in air.