top cylinder fouling

[boggi]

my 1982 e4w that i have had since new just started black sooty spark plug fouling on the top cylinder with my first start up this year. idle and mid range speed fine then slight noticible shudder at fast speed. so far ,compressions equal at 70, & increased to 90 with squirt of oil into cylinder. fresh fuel,new plugs,replace fuel pump, replace both mags, points, condensers, clean and reclean carb. removed carbon from cylinder head ,pistons, exhuast. timing checked good, spark gap good. this carb has a fixed high speed jet and is clean as best asi can tell with out removing the shot from the top of the carb. I've not pulled the intake off to check the reed valves yet. Any thoughts on checking the reed valvesor any thing i' ve missed?

 

[Joe Reeves]

Re: top cylinder fouling

(Magneto Capacitance Discharge Coils - Continuity Test))
(J. Reeves)

Check the continuity of the ignition coils. Remove the primary orange wire from whatever it's connected to. It may be connected to a powerpack screw type terminal, a rubber plug connector, or it may simply plug onto a small boss terminal of the coil itself.

Connect the black lead of a ohm meter to the spark plug boot terminal, then with the red ohm meter lead, touch the ground of the coil or the powerhead itself if the coil is still installed.

Then touch (still with the red lead) the orange wire if it's attached to the coil, or if it's not attached, touch the primary stud of the coil. You should get a reading on both touches (contacts). If not, check the spring terminal inside the rubber boots of the spark plug wire. Poor or no continuity of a coil is one reason for s/plug fouling.

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(Battery Capacitance Discharge Coils - Continunity Test)
(Joe Reeves)
Remove the primary wire the screw type terminal. Remove the coil and unscrew the HT wire from the distributor cap.

Connect the black lead of a ohm meter to the HT wire, then with the red ohm meter lead, touch the ground wire of the coil.

Then touch (still with the red lead) the wire that normally attaches to the powerpack output lead. You should get a reading on both touches (contacts). If not, check the HT wire by unscrewing it from the coil. After removing the wire, the check can be repeated using the internal threaded prong within the coil instead of the HT wire. Poor or no continuity of a coil is one reason for erratic or no ignition and/or s/plug fouling.

 

[boggi]

Re: top cylinder fouling

I checked the old mag coils off the motor&was unable to get any continuity. Disconnected green mag coil wire from the points assembly on both mags. was unable to get any continuity from either green wire to plug or mag black wire to plug connector. I'm thinking take mags off and check plug wire lead for continuity. the gaps are set with full throttle at the center of the lobe markingsfor /T O P/ i.e. at the "O". thanks

 

[boggi]

Re: top cylinder fouling

since my lastpost earlier today I'v checked spark plug leads & they check good . Point gap .020, good fire both cylinders,asy start, smooth low speed,& fast idle. Lake Test run for 30 minutes at full throotle still with shudder & fouled top cyl. with black sooty buildup. Swapped plugs between cylinders & run for 45 mins. at idle/fast idle troll speed with out a miss, but maybe a little vibration. Both plugs inspected & they look equal with a little oily film (the black soot burned off the previously fouled plug). Thanks