Re: 115 running on 3 cylinders
.....1, 2 and 4 are firing while 3, 5 and 6 are not.....
How did you determine which are 'firing' and which are not? Typically when we refer to 'firing', we are referring to spark related issues, which led Laddies to discussing what type of electrical symptoms would result in those behaviors.
Each switch box controls 3 cylinders, which leads one to expect 1-3-5 or 2-4-6 to be affected in unison if three cylinders stop functioning at once, as Laddies suggested.
Typically fuel problems affect a
pair of cylinders or
all cylinders at once. Top carb feeds 1-2 , middle 2-3, and lower 5-6 as you'd expect.
Your compression numbers sound good, so you can rule out major issues.
My next step would be to do a
spark check on each individual cylinder, to rule out ignition as the source of your problem. Only then would I look for fuel or timing related issues.
Broken or bent reeds show up as a rough idle, and typically they sneeze fuel out of the carb. I don't believe you've mentioned those symptoms.
Don't shoot carb cleaner or starting fluid into the carbs... motor requires lubrication. Use pre-mix fuel if you need to spray something.
Does the motor run at all, just rough running?
If it does run, does it behave differently as you advance the throttle?
Do you have access to a DVA meter to run any ignition tests?
