Kawasaki ZXR750J1

[Mark65]

Hey All
My work colleague has put his bike back together after his partial restore and is having problems with running, it will start and run fine on choke but as soon as the throttle is turned it dies?.
It has an electric fuel pump on it also if that helps, carbs have been stripped and cleaned checked twice, I thought it may be running to lean?.
Any advice please.
Thanks
Mark
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07 Yamaha YBR125, 07 Honda CG125 , 15 CBR300R (Chocolate Crank, Deaded), 16 CB500FA, 19 Honda Forza 300, 70 Suzuki SV650

[Iain.]

Did he let it warm up all the way?

My RF would do this unless it had had a few mins running on full choke.

[RhynoCZ]

What Iain says, warm it up properly. My ZXR also dies when it's cold and i try to rev it.
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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

[Mark65]

He says he let it warm up and after a bit it starts to smoke, thanks for your help so far.
Mark
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07 Yamaha YBR125, 07 Honda CG125 , 15 CBR300R (Chocolate Crank, Deaded), 16 CB500FA, 19 Honda Forza 300, 70 Suzuki SV650

[RhynoCZ]

Is it smoke or vapor?

Also, if the engine was taken apart and there are new piston rings in it, it is pretty common for some blue smoke to appear for the first couple of hundreds of initial miles.

If it still dies at the flick of a throttle, you're gonna have to check if there's water in the fuel system. The fuel pump only really works at constant high speed, to prevent it from the fuel starvation.
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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

[Mark65]

Engine was left alone, fuel tank was cleaned, carbs stripped and cleaned, checked twice, new fuel lines put on, not sure what the smoke is.
He says with choke half on it idles around 2k, choke off it dies, twist throttle is dies.

Mark
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07 Yamaha YBR125, 07 Honda CG125 , 15 CBR300R (Chocolate Crank, Deaded), 16 CB500FA, 19 Honda Forza 300, 70 Suzuki SV650

[RhynoCZ]

Did he fiddled with the idle settings? I'd start it with the choke on, and while on choke I'd turn the idle screw and set the idle faster than 2,000rpm. Then slowly turn the choke off, compensate the lowering revs with the idle screw. Then let it warm up properly with no choke, and after that set the idle between 1,500 and 1,200rpm.
I run the idle at 1,200rpm (+/- 25rpm) with no hesitation.

If that won't help, then I think the carbs are terribly off the sync.

Also, did he put an air filter there? No air filter would make the mixture very lean and what the choke does is that it restricts the air coming through, making the mixture rich. Meaning, if there is no filter, then no choke = too much of air.
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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

[Mark65]

Air filter is on, he checked fuel pump last night and it was fine, bike will start and run on choke, then starts to get a bit rough as it warms up, slightest tun of the throttle and it dies. He also adjusted mixture on all four carbs and it made no difference , starting to pull hair out now. any other ideas.

Thanks
Mark
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07 Yamaha YBR125, 07 Honda CG125 , 15 CBR300R (Chocolate Crank, Deaded), 16 CB500FA, 19 Honda Forza 300, 70 Suzuki SV650

[0ddball]

I had pretty much the same on mine after rebuilding it. To rule things out:

Make sure you are using fresh fuel and a fully charged battery. They are sensitive to a poor battery.

It still may be a blocked pilot circuit in the carbs, they can require multiple cleanings. With the carb bowls removed and the throttle slightly open, squirt carb cleaner with a straw though the ports at the front of the carb and make sure it squirts out of the main or pilot jet and also the tiny ports at the rear of the carbs ( under the throttle butterfly). Bench sync the butterfly's with a needle to have them all ever so slightly open on the throttle stop. It will idle high but this can be set properly when the engine is warm. Check the choke linkage moves freely.

To rule out air leaks, check the rubber carb mounting boots carefully and refit the carbs making 100% sure they are seated properly. Seal the vacuum ports under the manifold rubbers, disconnect the carb vent from the valve it is connected to and let it vent to atmosphere.

Also make sure the fuel line between the tank and the pump isn't getting squashed when the tank is fitted.
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ZXR750L

[Mark65]

Thanks, gave him your list
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07 Yamaha YBR125, 07 Honda CG125 , 15 CBR300R (Chocolate Crank, Deaded), 16 CB500FA, 19 Honda Forza 300, 70 Suzuki SV650

[Mark65]

Just to let anyone interested it was the pilot jets still blocked in the center, cleaned them out and the bike started and ran great, thanks Oddball.

Mark
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07 Yamaha YBR125, 07 Honda CG125 , 15 CBR300R (Chocolate Crank, Deaded), 16 CB500FA, 19 Honda Forza 300, 70 Suzuki SV650

[Mark65]

And here it is, lovely bike, not quite a commuter.
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07 Yamaha YBR125, 07 Honda CG125 , 15 CBR300R (Chocolate Crank, Deaded), 16 CB500FA, 19 Honda Forza 300, 70 Suzuki SV650