2002 Kawi zx6 carb issues

[Norcorider]

Few months back , I acquired a 2002 Kawi zx6 ( also called zzr600 in some markets ) with only 5k km. It sat in a storage for around 15 years. The bike is super clean.
Owner mentioned they had replaced all fuels and cleaned carbs, the bike ran fine for another 1k km. After that it started giving issues, I opened the air box, the filter was all crusty and torn at some places, most probably due to age. I also noticed the fuel filter was not looking that great either.
Replaced both fuel and air filter, bike ran okay for sometime but kept bogging down on first and second gear, I had to rev it up to get going from a stop.

Now it just dies on the touch of throttle. It idles fine, starts fine from cold with choke on. But no matter how long I keep it idling and letting it warm up, when I try to give it gas, it dies.

There was no rust in the tank what I could see , there was some rust under the fuel cap and on the fuel filler opening, which I not there anymore once I started using the bike.

Am I dealing with carb issues, or something else?
Do I need carb rebuild? Already tried a full tank with stp carb cleaner, I think it made it run worse.
Please advice. I would like to fix it during winter hibernation.

This is my first carb bike, I can do basic work on my bikes following instructions/service manual/ YouTube videos.

 

[chingo]

My 98 ninja zx9 had issues with bogging due to air induction issues, from the feed to the carb, you might want to check that,
not sure if 2002 has similar setup.

 

[GreyGhost]

Regardless of km, if the carbs haven't been apart in 20 years, there is a good chance things aren't flowing properly. Low km's probably makes it worse as they didn't have a ton of fuel flowing through them to scrub deposits.

 

[Norcorider]

Found a carb and petcock rebuild kits on fortnine. The petcock is super stiff, very hard to turn . I think I am going to rebuild both, hopefully that will address the issue.

 

[ReSTored]

Owner mentioned they had replaced all fuels and cleaned carbs, the bike ran fine for another 1k km. After that it started giving issues.

Really depends on what the PO did to clean the carbs, could mean anything from complete disassembly to just pulling off the float bowls to running some carb cleaner through it. The rebuild should solve this problem. Do you have an ultrasonic cleaner? A good soak and a few cycles would remove all of the crap. I'm no carb expert, but I think you're going to find that some gummed up particulate matter has come free after 1,000 km and is now partially or fully blocking a key jet or circuit in the carb.

If you haven't already done this I'd be looking at brake, coolant and fork fluid change out + cleaning brake assembly, pistons, pins etc....

 

[Norcorider]

Really depends on what the PO did to clean the carbs, could mean anything from complete disassembly to just pulling off the float bowls to running some carb cleaner through it. The rebuild should solve this problem. Do you have an ultrasonic cleaner? A good soak and a few cycles would remove all of the crap. I'm no carb expert, but I think you're going to find that some gummed up particulate matter has come free after 1,000 km and is now partially or fully blocking a key jet or circuit in the carb.

If you haven't already done this I'd be looking at brake, coolant and fork fluid change out + cleaning brake assembly, pistons, pins etc....

I don't have an ultrasonic cleaner, I will try to find one.

About rest of the fluids, you read my mind. Replacing all fluids is on my to-do list. I did change out engine oil and filter few weeks back. Brake fluid and coolant are sitting on my shelf for winter maintenance.

 

[timtune]

When you fire it up do all four pipes heat up at about the same rate? (A quick indication all four carbs are doing their bit - at least to some degree)

 

[Norcorider]

Took carbs apart and rebuilt them with all balls racing carb kit from fortnine. Bike purrs like a kitten now.

I noticed the carbs were in fact opened before the bike was sold as I saw marks on some screws. The culprit for poor running was that the pilot jets were clogged on two carbs, I found evidence of disintegrated old air filter in carbs, I suspect that is what clogged the jets. Explains why it was running fine for the initial 1k km and suddenly started giving issues.

A few problems I ran into on this job : one of the float bowl screws was stripped, my buddy helped me take it off by adding a cut using dremel and then open it with a flat head screwdriver.

The other is while putting the airbox back on, +which is extremely frustrating as it's really hard to put it in the ram air pipes) the cable of one of the coils came out. I only noticed when I started the bike and noticed a spark under the air box. Had to take off the fuel tank, airbox again and redo.

Other than that, it wasn't too bad for my first carb job.

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