I've searched three different forums and can't find an answer.

I'm working on sync'ing or balance my triple Mikuni carbs. I've done this several times on motorcycles with just a vacuum gauge with great success. I know it's not a Unisyn or similar, but patience yields just as good results.

The vacuum advance for the dizzy is connected to #1 carb.

The middle carb doesn't have anything, and I can't get a vacuum reading on the port.

Third carb, can't get a reading.

I'm trying to connect to the same place the advance tube is connected to on the #1 carb, but I don't have the tall nipple like on the #1 carb.

What am I doing wrong?

Thanks!

JM

 

On closer inspection, I removed some hex screws from the Mikuni manifold, and I found that I did have access to the intake runners. However, they are blocked with some type of semi-firm sealant material. It's soft enough I can press a knife tip into it. Is this normal, or did someone do this to prevent vacuum leaks?

One pic shows overall, I have the allen screws out, but you can't really tell much about them.


Closer pic - turns out it's not solid, it's a white-ish sealant looking material, but very stiff. I can get the tip of a knife blade to dig in.


JM

 

That's an asbestos blanket to sheild heat from the carbs. You need to replace the vacuum hose and make sure your advance is working with a timing light.

 

I've done both of those. My timing is 10 or 12 degrees at idle, and advances as I bring RPM up.

The round opening with the white stuff inside in the intake runner was what I was asking about. I did know that is a heat shield to keep from boiling the fuel in my carbs.

I'm wanting to know if I can remove the sealant from the threaded holes in the intake runners and take a vacuum reading there and re-seal.

JM

 

Now I see it. That is a possible place but I doubt if it is threaded.

 

It is, I had to thread a hex-cap out, and found this. I just wanted to make sure it would be a good place to pull a vacuum reading ~

JM

 

I think that would b a good way to balance the carbs if you could install a vacuum port in three of them and compare readings.

 

That was what I was thinking. I'll see about locating some type of port and remove three of the sealant plugs. I'm used to balancing with vacuum readings since I work on motorcycles.

JM

 

That's a very effective way to balance carbs. If you had 3 gauges you could do it in a minute, good idea!

 

Yea, three would make it super fast and easy. I've just got the one though, it'll still only take me 5 minutes to get them right!

JM