GPZ 550 Starting Issues

Hello there!

You guys were a great help getting spark back into my bike, but I'm still having troubles getting this guy started so I thought I'd pick your brains again!

Just for reference, I'm rebuilding a 1983 Kawasaki GPZ550 that hasn't been ran in a long time.

I have spark at all cylinders (confirmed with spark plug tester), the starter motor works (turns over the bike), and though I haven't checked compression yet (don't have a tester, borrowing one soon) I believe it's good as I've gotten this bike to start once.

So once I got spark working, I took the carbs apart and cleaned them fairly thoroughly. Everything seems to be unclogged, and when I put the carbs on the bike I checked to ensure all float chambers were getting fuel (by opening each drain port individually). So we have good spark, fuel to the carbs, and starter motor works. I tired firing it up, and after a few tries the bike roared to life, for about 5 seconds, then died. After a few more tries I got it to come back one more time, and then it died very quickly again. Since then I haven't been able to get it to fire again. Sparks still work, still have fuel at the carbs (even cleaned them again), but no firing.

Assuming compression is good (which I will verify at some point here), where could I be going wrong? A couple of notes:

• I'm trying to start this with the airbox off. I don't think that should affect a start up but please let me know if you disagree.
• I'm using a motorcycle battery from another bike, that I don't think is neccessarily sized for the GPZ but it's the same voltage and seems to work, again I dont think thats an issue but let me know if you disagree.
• I'm getting a new fuel tank so currently I'm just feeding the fuel line with a makeshift bottle.

Thanks in advance for your help!

-Brandon

Airbox off will make a huge difference causing very lean air/fuel mix.
Put airbox back on and try again
good luck

•I'm trying to start this with the airbox off. I don't think that should affect a start up but please let me know if you disagree.
•I'm using a motorcycle battery from another bike, that I don't think is necessarily sized for the GPZ but it's the same voltage and seems to work, again I don't think that's an issue but let me know if you disagree.
•I'm getting a new fuel tank so currently I'm just feeding the fuel line with a makeshift bottle.


1) It does make a difference, but probably (I think) not enough to prevent it from starting. You are using the choke? It might be worth checking your fuel levels in the carbs with a U tube. Just to isolate this as a fuel issue, drain the carbs and try some starting spray or carb cleaner, it should fire up on that and run if your ignition is ok.
2) 12 volts is what it needs, use a fork lift battery if you like.
3)no probs, just make sure you plug the vacuum pipe to the fuel tap.

Hey guys,

Sorry I got held up yesterday and didn't have a chance to try the bike with the air box on. I will take a shot at this today.

Tyrell, you mentioned that I should plug the "vacuum pipe to the fuel tap". I've been a bit confused about this idea. I believe that on these carbs the vacuum pipe is on the second carb in, on the fitting that is plugged for the other 3 carbs. My understanding is that the vacuum pipe opens the fuel valve for the gas tank. The makeshift bottle I'm using has no fuel tap, it's just open to the carbs. Is that ok?

-Brandon

Update:

Yesterday I tried starting the bike with the air box on, still no luck. Everything appears to be turning over well and I still have spark...

I cleaned the carbs fairly well (twice actually), but I suppose it's possible that they could still be gunked up... or potentially I've set something wrong on them?

As another note, the air box took a decent amount of effort to get on, and the boots that go to the carbs were pretty stiff, so I'm not convinced they are perfectly sealed, so maybe I'll try with some duct tape around the boots to ensure a seal?

-Brandon

The airbox should not effect starting. There is so little airflow on startup that it makes no difference. I am working on an 1100 that is doing something similar, and found that even though the previous owner spent a lot of time and money replacing stuff in the carbs and cleaning them, he did not remove the idle mixture plugs and get the idle mixture screws out and clean in there, and it will not really start or idle.

Do you have TK22 carbs?

That bike should have TK26 Carbs and the idle knob sits between #2 and #3. When you went through the carbs, did you see that there were main jet plugs in place like in the picture below? If not, that that is part of the running problem.





Are you running all stock jetting or did you install a jet kit? Valve clearances checked and set?

It doesn't matter which vacuum port on the carbs you use for the petcock, just make sure the others are not open as this will create a vacuum leak and a lean condition.

brandon22 wrote:
Tyrell, you mentioned that I should plug the "vacuum pipe to the fuel tap". I've been a bit confused about this idea. I believe that on these carbs the vacuum pipe is on the second carb in, on the fitting that is plugged for the other 3 carbs. My understanding is that the vacuum pipe opens the fuel valve for the gas tank. The makeshift bottle I'm using has no fuel tap, it's just open to the carbs. Is that ok?

Just to clarify: The bottle isn't a problem but the vacuum pipe has to be blocked off so the carburetor won't suck in air through it.

Hey guys, thanks for the responses.

Yes my carbs look exactly like those shown in the picture Corey posted.

My carbs DO have main jet plugs in place. I didnt remove them to clean them during my cleaning process however.
I have the vacuum piped plugged off so that shouldn't be the problem.

Following DGA's response I'm taking the carbs off and cleaning them again. I dont believe I removed the idle mixture screws either so I'll take a shot at cleaning those as well and trying again. My only concern is once I remove them I'm not sure how deep to put them back in but I'm sure I can find that somewhere.

Thanks again!
-Brandon

Sorry, and to add to that:

Corey:

Just stock jets, nothing new there. Haven't touched the valves yet...

Download the free manuals in my signature.

What spark plugs, and what do they look like now, or are they new? Did you set the gap of them?

It starts so you have air fuel and fuel. If it dies, then you might be running out of fuel. Is the petcock on PRI when you run it?
Did you install a new rebuild kit on these carbs, or just clean them up? Could be the mixture screw o-rings are leaking past that o-ring on them. The manual will tell you where to start with these screws, but factory settings are lean.

Check to see if the slides are going up and returning down by lifting them with your finger from the air box side. Check the diaphragms to make sure there are not any tears in them. Watch from the air box opening when you start it and see if fuel is coming up the slide needle hole into the carb.

Check the slide needle number with what is in the manual to make sure you have the right ones in there. You are not the original owner, so who knows...