1980 KZ750 LTD H - welch plugs, fuel adjustment screw, fuel mixture

Hey all,
Question about the fuel adjustment screw on the Kei Hin carbs. I have small metal plugs blocking the holes. (I believe they are called welch plugs). I pulled apart and cleaned the carb body and parts, put everything back on and now I'm having hard starting and idle'ing. After research it appears I'm running lean, so down to the question.

Should I pull the welch plugs out and adjust the screw to increase fuel flow or should I be going down the list of sync'ing carbs and checking for any air leaks? Is there a reason they are plugged, and I shouldn't be messing with it. I just replaced the the rubber boots on either end of the carb, so I don't think an air leak could be coming from them. Thanks for any advice, first bike I've worked.

You're supposed to drill out the plug and remove the pilot screws so the passage can be cleaned out. Be careful because once you remove the screw there will be a spring, metal washer, and O-ring down in the passage that needs to be fished out. A new O-ring is strongly advised and when you install the screws set them at about 2.5 turns out from lightly seated as a good starting point, then tune them a little thereafter until you achieve the highest idle and smooth off idle performance.

Roger that, thanks much. Should I replace the plugs when finished? Or does it really matter if they are out?

You can leave them out to facilitate further adjustments. They were installed to make them"tamper proof" when the days of emission standards started for motorcycles. Before the caps I think there were small plastic limiters that allowed a bit of adjustment. Probably about the same time they quit putting needles in carbs with slots and clips.

Mike

Thanks guys, I bought a repair kit and removed the plugs, replaced the o-ring, washer, spring and screw. Hooked it all up and now when I start it, it starts instantly and jumps fast to 6k rpm in a sec so I kill it, adjust the screws and the idle adjustment and still jumps fast up. Any ideas on what I might have done

I assume you have free-play in your throttle after removing and installing the carbs?

Mike

good starting point, I'll check it, wanted to lube up the throttle cable anyway.

Check for air leak.

Check for air leak. Also see that the RPM adjuster is properly set.

For others benefit, the quick jump of rpm's as if the throttle was fully open when I start the bike seemed to come from a clogged pilot jet. Still a long way to go to get it running smoothly enough to ride, but at least one less thing.