This is weird!

Get this, I pulled out the plugs over the idle pilot screws out of the carbs while disassembling them for the second , no third time. Well, I checked the setting on the screws before removal. #1 was 2 turns out, #2,3 and 4 were closed. I dont know who or when this was done but PO had said it took over a week for the local race shop to tune them. Have any of you heard of any reason to need to set them like this? Also, what might you think the shop would have done to overcome the pilot valve condition? I am amazed it ran at all as well as it did but I noticed it wouldn't run well under load. That was why I pulled the carbs off again. Some background, compression was good spark was weak but there. Any ideas would be appreciated. This is a police bike so that throws me off a bit too.

You're talking about the mix screws right? Guessing they are air screws on your bike? Way off carb sync will cause mix screws to have wacky settings. Mine were from almost closed to three turns on the set before I set sync. Now they are all very close..within 1/4 turn on all 4 screws. Three are exactly the same.

If my memory is any good, it seems like I've seen old replies by wiredgeorge (of WGCarbs.com) in which he stated that the air screws can be set all over the place at the factory, but I don't recall if he had a plausible explanation. So you have to assume they are incorrect & start from scratch w the carb sync n stuff. It would probably help if someone can tell you a good starting point, such as 2 turns out or whatever.

The plugs over the pilot screws didn't look as though they had been replaced. The bike is a 1990P. I just imagine what the maintenance mechancs had to do. Anyway, bench sync then adjust air screws then full sync then air screws? Where does it start and end? I'm just glad I removed the plugs and hopefully I will not have as much trouble with tuning. Is it more than one cycle of each or more than one? I haven't done this work before but have spent a lot of time reading the great advice here! Great resource! Thanks, Keith

Markovich wrote: Anyway, bench sync then adjust air screws then full sync then air screws? Where does it start and end?

You got it....it is kinda cyclical. One thing effects the other. This is also assuming you don't have air leaks thru carb boots or anything else wrong. Vacuum sync is one of the last things you do, that's your fine tuning.

When I was working on mine I did bench sync, then set mix screws to highest idle. I rode it like that for a long time while I worked on other stuff. I just finally vacuum synched the carbs after tweaking other stuff on the bike for a few years. So bike should run and ride fine with a good bench sync is what I'm saying.

My service manual says to check all these other things before doing vacuum sync...

Check engine oil, spark plugs, ignition system/timing, throttle cables, air filter, air ducts and carb linkage, compression, valve clearance, and cam chain.

If you get a book (factory service manual, not clymer or hayes) for your bike it should have a list like this and then details for how to do each step.