Carbs wont Sync

Hello everybody!

Just a week ago my 77 1000 ltd was running good then all of the sudden it was running roung it was cold on numer 3 exhaust header. The plugs were dry so i took off carbs to clean them i suspected dirty pilots before anyway. I sprayed carb cleaner through all holes with fuel and air screws out, and blew compressed air through it. I made sure to put the springs back in.

I started it and it was running on all four.

I warmed it up and took it around the block and exhaust header temps were 510-550 but only around 270 on 3.

It was running like it was out of sync and temp was off so i put the sync on it sure enough 3 was no vacuum at all. I was actually able to turn it about a half turn or so to get it to come up and was able to get them to even up a bit but it raised the idle and turning the idle screw does not lower it. So i tried to lower the vacuum levels but could not get it to sync. Every time they start to get close it wont idle down. Another weird thing is on 2 carbs when i turn the screw out it raises the vacuum level on the other 2 carbs it is opposite it raises when you turn the screw in.

I have mac open 4-1 with cheap air pod filters 115 mans 17.5 pilots needle one notch richer than stock. Air screws at 2 turns fuel screws at 1 3/4. But this is where i had it set before and i had just done a sync two weeks before and it was running pretty good and it did not seem nowhere near this hard to sync.

Am i missing something?

Check your spark plugs, I bet #3 is fouled.

Thanks Baldy i will check when i get home. I dont think that the plugs were causing my problems because when it was not firing they were all dry, i also put a brand new clean set in and they were still brand new when i started the sync. But i do know i have weak spark at the coils only 10 to 10.6 volts, so i need to do coil power mod, but i have synced the carbs twice before with the weak spark and did not have problems getting them to sync.

The plug was fine it was the lightest color. I am about to get some gas and give it another go

So i just got done trying to sync for about ten minutes or so.

I have no problem getting the levels to line up the problem is that the rpms come up when it is balanced and then it wont idle down. Turning the idle screw does nothing at all.

So i thought that i would turn the screws down which lowers rpm and then raise the idle or that it would be able to idle down. So i tried this and gradually turned them all down about 3 whole turns give or take and still same problem. The rpms still come up when they start to get balanced which i thought was normal, and it still wouldnt idle down.

Im letting it cool a bit then i will try some more

Stop jackin with the carb's and fix the low voltage to the coil's first.

Another thing i thought i would mention is when turning the screws down this lowers the rpms except on that number 3 carb the rpms come up when i turn the screw down.

thank you zukdave

#3 is the lead carb. You set the others to match. You may have bad contacts in the ignition switch or kill switch. Check them. One thing at a time. :whistle:
Steve

The coil mod is rarely, if ever, necessary. Usually, a careful and systematic cleaning if the connectors and ground wires will let the juice flow. A good battery is also required.
Once the electrical issues are solved, you may find that the intake manifolds leak, or that the idle adjustment screw is too far out to begin with. When doing the initial synchronizing (on the bench) the first thing to do is to insure that the idle screw is in the middle of its useful range, the set the initial gap on the butterflies. This will allow maximum final adjustment in both directions.

So my problem turned out to be because the vent on number 3 was not plugged. I must have forgot about it then blew it off with compressed air. It is synced and running good now

kz kev wrote: So my problem turned out to be because the vent on number 3 was not plugged. I must have forgot about it then blew it off with compressed air. It is synced and running good now

That happened to me on my ZRX, except it was on #2.