68 evinrude 9.5 firing sporadically with timing light........

[moevinrude]

Yes its me again. This site has been so helpful. Thanks for the help to all!

I have had this mis I am working on. Got a timing light and wow. Both cylinders are firing about half the time. I cannot believe this motor actually starts on the first pull. It will fire 6 to 8 times and then misfire 2,3 maybe 5 times no pattern.

I have replaced the plugs, gapped at .030. Gapped the points .020. Soaked the carb and cleaned it real well. All jets are open. I even had 2 spare coil packs and tried them,,,,same results. Could the condensers cause this? I checked for a short in the dark and nothing there. Really confused. Please help.

 

[kbait]

Re: 68 evinrude 9.5 firing sporadically with timing light........

Condensers certainly could cause it, as could wires arcing, or wires not connected properly to plug boots, or coil connections. If you don't replace the wires, be sure to cut 1/2" off when re-seating to another coil. Did you clean the points to shiny??

 

[moevinrude]

Re: 68 evinrude 9.5 firing sporadically with timing light........

I will check for possible shorts tonight. Will let everyone know tomorrow. Thanks

 

[steelespike]

Re: 68 evinrude 9.5 firing sporadically with timing light........

Is the stator plate stable? Are the coils aligned with the bosses on the plate?
Is the top crank bearing good?When setting points the flywheel key should align with the rub block.Are the points clean and not pitted?Good spring tension on the points?

 

[Joe Reeves]

Re: 68 evinrude 9.5 firing sporadically with timing light........

(Magneto Armature Plate)
(J. Reeves)

If the armature plate has a a loose fitting, wobbling motion (the plate that the points, coils etc are attached to), it is usually caused by a slightly worn support ring. This allows the point setting to change erratically as the armature plate turns.

The cure is to remove the armature plate so that the support which is attached to the powerhead with 4 screws is visible. Then, with a screwdriver and hammer, or some tool of your choosing, and looking straight down at the support ring, make an indentation at what would be called the 12, 3, 6, and 9 O'clock positions. Install the armature plate and check for a smooth turning wobble free movement.

You may need to do that procedure a few times to obtain the proper fit (not too tight, not too loose), but it's worth the effort.

Use a small amount of anti corrosive grease between the aluminum ring and the brass support plate and also on the brass bushing of the armature plate when all is well.

(Point Setting Of Magneto Models)
(J. Reeves)

Set the points as follows. Have the flywheel key aligned with the fiber rubbing portion of the ignition points. Adjust the gap so that a .020 gauge will pass thru but a .022 will not. Should there be any question of the points being dirty (touching the contact with your finger would cause them to be dirty), clean them with a small brush and acetone or lacquer thinner.

NOTE: Should the operating cam have a small portion on it with the word "SET" imprinted, align this portion with the fiber rubbing portion instead of the flywheel key.