Getting My 86 Fired!!

You're the 4th person here with an '85 or '86, I know of, having the same problem. Well, symptom anyway...

be sure you didn't interchange main jets between carbs. Although the carbs look alike, two are side draft and two are down draft.

do you have the vacuum lines for the float bowl vents etc etc all hooked up correctly so there is no open vacuum leak?

Did you balance the carbs? The slide is operated by engine vacuum and if the balance is out of wack then it's possible for the cylinders to fight each other.

All that assuming the carbs were cleaned properly, float level set right, sufficient fuel supply, and spark.

 

It is possible that the problems are connected but not deffinately.

The two cylinders lacking to fire when cold would typically point to the choke circuit. When the engine is cold, it needs more fuel. A warm engine will atomize the fuel easier and creates a mixture more conducive to ignition. Once the engine warms up a little from the two cylinders that are firing, the other two come on line from the fuel in the pilot circuit.

When you took your carbs apart, there are three bronze "stacks" that stick down into the float bowl. Two of those stacks are removable and they are the jets. The third one isn't removable but the passage goes all the way up the carb housing and opens up again in a hole near the slider diaphram. I believe this passage is part of the choke circuit too and it's easily missed.

You have to remove the silver caps at the top of the carb (carefull not to tear the diaphrams) and you'll see the choke plunger and a few more holes to make sure you have clear. At the front of the carb, where the air would come in to the engine, there may also be bronze nipple sticking out with a hole in it. This should also be part of the choke circuit. When the throttle butterfly is closed and the choke is open, air enters this tube, mixes with fuel in the passages I mentioned earlier, and enters the engine thru a port at the twelve o'clock position just behind the throttle butterfly.

 

The reason I say this problem may not be connected to your surging issue is because the carburators are actually 4 or 5 different systems all in one. When you roll on the throttle, the vacuum created behind the throttle butterly is reduced and the choke circuit no longer delivers fuel. At that point, the pilot jet is delivering fuel to the engine. As you continue to roll on, there is a transition from the pilot jet to the slow speed jet, and the transition continues to the main jet/jet needle, and on to the main jet only at wide open throttle.

And all that said, your problem can be caused by other factors as mentioned earlier - vacuum leaks, fuel filters, inadequit spark...

Did you find the fuel filter screens behind the float needle? Unscrew the needle/seat and there should be a fuel filter/screen there.