Idle Adjustment / Throttle Stop setting on 1990 Zephyr KZ 550 B

I have a KZ 550 with newly rebuilt and synced carbs. The bike was running well before the idle screw had been changed some unknown numbers of turns and directions. Is there an intelligent method that anyone has used to find the best setting for the idle adjustment given that the bike will no longer idle on its own?

After a carb rebuilt first turn in the pilot screw until it seats slightly with a very little resistance, then turn the screw two and a half turns out = basic setting.

Thanks for the quick reply. My question is about the idle adjustment that is accessible on the side of the bike. Tuning it hasn't been intuitive to this novice and I'm fearful of making things worse.

Just turn it one way or the other until you get the proper idle rpm, typically around 1100rpm.

When he carbs were being reassembled after the rebuild, that screw should have been set near the middle of its adjustment range, so you should have plenty of adjustment range in either direction.

Make sure the engine is fully warmed up when you set the idle speed.

P.S. If the mixture screws were not fine tuned , and the carbs were not synchronized to each other after they were reinstalled, then jacking with the throttle stop adjustment will likely not cure the problem.

At the current throttle stop setting, the bike will no longer idle on its own. I can keep the bike running by finessing the throttle. Even after it is warm, the engine will kill upon release of the throttle. If the engine kills immediately, how do I make idle adjustments? Sorry - I am less than 1 week into bike ownership.

While finessing with the right hand, use the left hand to slowly turn the adjustment screw clockwise until the engine will idle without messing with the throttle. Once it will idle on its own, then use the adjustment knob to set the idle speed to factory spec. If you cannot get the engine to run at the specified speed, then there are other problems.
Please get a copy of the genuine factory service manual for your exact year and model. It may be available to download free. If not, constantly search eBay and such. It will save you a great deal of time, frustration and money. Some of the aftermarket manuals are ok, but none are as complete and specific as the proper fsm.

Here are some links to Lou's website. There is a truckload of 550 info there, and just maybe the fsm you need.

www.kzrider.com/forum/8-about-the-site/600635-signature#702657

A 1990 550 Zephyr 550 is a ZR550-B1 (not a KZ). If the bike was running good beforehand, why were the carburetors rebuilt?
The carburetors should be synchronized and fine tuned on the motorcycle while it is running.
You should have to use the starter/choke lever to start and warm up the motorcycle in cold to moderate ambient temperatures, this is normal.
The owner's manual may have a Starting the Engine section that gives guidelines that are useful.
note: choke/starter carb fuel circuit is not to be confused with the electric starter.

When was the last time the valves were adjusted?
Steve

Thank you for the clarification on the engine model. I'd like to change the title of my post if possible. That's just additional evidence of my lack of knowledge and experience, surrounding this new venture of mine. I appreciate any support and insight.

I acquired the bike in excellent running condition after having a recent carb rebuild and synchronization. Unfortunately, shortly after it was in my possession, I managed to flood the engine with petrol after having left the non-stock manual petcock in the open position. I drained the oil and pulled the filter to remove any fuel from the crankcase. Following the oil and filter change, I tried with rookie effort to get the engine to run. With no evidence of combustion, a friend spun the idle adjustment with no attention to its original setting.

Recently, after draining the bowls, the engine will fire up with minimal effort but no longer holds idle on its own (anywhere along the choke range). With just a hint of throttle, I can keep it running at idle speed. I recognize that the haphazard adjustment of the idle was ill-advised and I'm hoping to go about its retuning in a more thoughtful manner

Does this thumb adjustment on the side of the bike (photo, right) terminate/connect to the pilot screw in the photo on the left?

jwtulane wrote: Does this thumb adjustment on the side of the bike (photo, right) terminate/connect to the pilot screw in the photo on the left?

No.
A pilot screw (aka mixture-screw or air-screw depending on the carb construction) adjusts the ratio of air to fuel when the bike is idling. Each carb will have its own pilot screw. Some rare carbs will have two on each carb. The pilot can be on top, on bottom, or on the side of the carb. If its on the side, but closer to the engine, that usually makes it a mixture screw where the screw affects the ratio by controlling the amount of fuel(mixed with a little air) supplementing the throttle opening's air. If its on the side closer to the airbox/air-cleaner, then its usually an air-screw where the screw controls the amount of incoming air into the pilot system.
Air screws might be a little trickier to set, but they tend to be less problematic in the long run, in terms of gumming up and cleaning, since they never get fuel on them.

An idle screw (aka idle-speed-screw or throttle-screw ) controls how much the throttle is open when the bike is at idle. It sets the minimum throttle opening position, which is when you let go of the throttle. This adjustment has one knob that affects all four carbs. The knob can be in the middle, above or below the rack, or on the side of the rack using a remote cable.

The two things are very different.