TOPIC:

Hi,
Can anyone clarify the best way to set the carbs up with vacuum gauges

I've been told that you only need 3 gauges as there is no adjustment between chokes (within each body)
only between carb bodies. And I've also been told the inlet manifold have 6 inlet screw holes
for a reason,

The engine idle seems to be a bit lumpy at idle, any ideas on set up,,

cheers Pete,

Just finished 2 1300's Pete, I used the two otters, and the easier centre. In other words one for each carb respectively. There shouldn't be a difference between the two butterfly's in each carb, if there is for some reason, then it's to do with wrong valve adjustments which effect vacuum, worn pins on butterfly's etc.. Could be a few reasons. But hopefully that is not the case and should balance up ok. Keep in mind for a running bike, ie: only re-adjusting, you turn the adjusters very little either way, and but that I mean like quarter turn at a time. When reading the gauges, remember when the vacuum goes up, you are closing the butterfly and down, opening. You want it around minimum 14CmHg. Mine are around the 20 mark.
Also check your idle jets. Start at 3 1/2 turns out on each.
Hope this helps.

Hello Pete:

You can sync with three gauges but you will want to swap back and forth a few times to make sure all are within 2 CM within each other.

You right in that there are 6 ports for a reason. Even though there are only 3 balance adjusters, reading all six ports will tell you if there is something off in the throttle bodies. Either mechanically in the engine, or within the throttle bodies themselves. this can be due to a blockage in the idle circuit in those non-adjustable throats, or possibly the butterflies themselves can be bent or misaligned.

So check all six to make sure.

I happen to have two 4 port manometers, which allows me to check all 6 at one time.


Before you begin the carb sync, make sure of the following:

1: your fast idle cam is adjusted per the book, at least start with that measurement

2: If possible, take the carbs off and bench sync them with a fine wire first. This will dial them in fairly closely and will assist you with a less than lumpy idle.

3: It would be a good idea to adjust your idle mixture screws out around 3 to 3.5 turns out, then adjust with a infrared gun, or ColorTune plug. (Most on this forum suggest the ColorTune method.) There are some good YouTube videos on how to use that tool.

4: As you adjust your blance adjusters, make sure they are adjusted within the limits of the manual. Too far in, and the bike will not idle, too far out and the throttle linkage will bind. (I think it is no more than 4 turns out)

Keep us posted.

Todd.

Ugh, reading this has my stomach in knots. I too have to travel down this road. Is it a difficult task? I've had the carbs off when I first got the bike, but not since (2+ years). Any tricks for a first timer? Anyone in southeast Pennsylvania to hold my hand? Most of my other carb'd toys only have one.

I am not in pa but I am in Ohio in the center part. Its really not as hard as it sounds with the right gauges. my email is This email address is being protected from spambots. You need JavaScript enabled to view it.. the bigest trick to this carb thing is to set them up right on the bench before you put them on the bike. Makes things go a whole lot smoother. Email me I walk you thru it.

Thanks Guys for the replys,

I did however try to get all the butterflies matched as close as poss by eye when on the bench, I think I will get myself two lots of four gauges so all six
cylinders can be checked at once.
I just hope that the lumpy idle is only due to the carbs being out a bit and nother more serious going on,,,,, Ive got good compression on all six but it has been suggested that I could still have a valve not seating properly,,, I really hope thats not the case.

Anyway thanks again, Pete.