Topic: Two cylinders not firing

[Brixie387]

Trying to get my 1981 CB650 back on the road - she had been down with fouled carbs.  I had the carbs professionally rebuilt and now the bike will start and idle nicely, but cylinders #2 and #4 are not firing (those exhaust pipes do not get hot, while #1 and #3 do get hot).  So far I have done the following:
1.  Replaced both coils
2.  Replaced all four plug wires
3.  Confirmed that all four plugs are good and are sparking
4.  Tapped on all four carb bowls to make sure needles aren't sticking
5.  Poured a little gas into spark plug holes #2 and #4, reinstalled plugs, started bike
None of this solved the problem.  Do any of you experts have any advice?

[rocket johnny]

points ?  condensers ??

[Brixie387]

I have the the left coil wired to cylinders 1 & 4 and the right coil wired to cylinders 2 & 3.  That's what is so confusing, I am getting one cylinder firing from each coil (1 & 3 are firing, 2 & 4 are not).
I have switched the two wires within each coil - no change.
I have switched the spark plugs on cylinders 3 & 4 - no change.
Any others ideas???

[evinrude7]

not familiar with the 650 but try float height  i had that issue when i tried to get my bike running a couple few years ago. 

[Spanner 1]

Wrong coils maybe.  You might have wrong impedance coils ( ohms ) to match the 650's electronic ignition , or if the plugs on 2 and 4 are dry, then low fuel issue in those 2 carbs. Also do you have the correct plugs?, should be resistor plugs.

[Brixie387]

Wrong coils maybe.  You might have wrong impedance coils ( ohms ) to match the 650's electronic ignition , or if the plugs on 2 and 4 are dry, then low fuel issue in those 2 carbs. Also do you have the correct plugs?, should be resistor plugs.

Coils are correct (after-market replacements for Honda part number 30500-422-013). 
The plugs are NGK D8EA, which matches what is specified in the Honda shop manual, but the D8EA is not a resistor plug.  Why should I use different (resistor) plugs?

[TwoTired]

Four cycle engine.  Suck, squish, bang, blow.  Needs all four to run.

Are the spark plugs for non-firing cylinders wet with gas?  (no spark but drawing air/ fuel.)
Have you verified that the non-firing cylinders have proper compression?

Cheers,

[Brixie387]

Update:  I took her out for a 5 mile spin and all four pipes were blazing hot when I returned.  Not sure what caused the 2 & 4 cylinders to finally fire, but I'll take it!  Thanks to all who helped.

Now on to the slipping clutch, sticking throttle cables and lack of front brakes...

[Don R]

 Adjust clutch lifter, check cable routing and slack adjustment, Rubber band on the brake lever tap the hoses and let sit overnight.  That's all I got. L0L! Good luck and ride safe but ride.