Air screw adjustment

Hi guys,

I've got my 1994 Copbike1000 running strong. The only thing that has finally gotten to me is cold starting the bike. When doing so, the bike sneezes and pops. I also get plumes of smoke. As the engine warms up, it begins to smooth out and the sneezing and popping and any smoke goes away.

Once the bike is at running temp ALL is good. I've replaced the pilot jets, which made a huge difference in ride-ability. Do any of you guys recall the process for adjusting the air screws? I want to get this right. As I stated, the bike runs very strong and engine is smooth through it's power band. I do not want to hurt performance by adjusting the carbs incorrectly!

OK. First off: The KZ1000P carbs don't have air screws. The idle mixture screws are fuel screws. Clockwise is leaner, counter-clockwise is richer.

The generic setting for a stock bike is about 2 turns out from lightly seated. However, you need to be aware the screw holes and passages have to be clean and the o-rings on the screws in good condition to be able to identify lightly seated properly. If something's dirty then they can get stuck. If you turn them in too tight you'll damage them. On the bright side, the screws can be removed without removing the carbs. Each screw has a fine point on it. If the point is missing, you're going to have to take out the carbs and repair the damage.

The procedure for setting them varies with what equipment you have available and what your goal is. I.e. performance vs. economy.

To set for performance, set them all to 2 turns out. Set the curb idle to 1000 RPM. Then, turn one screw at a time in until you hear the idle drop, then start slowly turning it out until the idle goes up again. There will be a point when the idle begins to drop from being too rich. Turn the screw back in to the point the idle was highest. Reset the curb idle to 1000 RPM and repeat for all the other screws. After this adjustment you'll have to resync the carbs because the mixture affects the vacuum readings.

Blip the throttle to check the off idle response. If it hesitates, right setting all the screws 1/8th of a turn richer until it goes away.

No adjustment of the mixture screws will have any effect on smoking. But too lean of a setting can cause backfiring.

If you have pods etc, all bets are off. You'll probably have to begin at a richer starting point. Also, you don't say what pilot jets you put in... That affects the range of adjustment of the mixture screws also.

Your smoking problem sounds like worn valve guides/seals (smoking before warming up esp. after sitting overnight.) If it smokes worse when you rev it up even after running for 10 minutes, then it's probably worn piston rings.