'76 Johnson 35 HP backfires PICS

[cbuckla]

I'm having some issues with my motor running smoothly. I put 12v to the coil because I hooked up the ignition switch wrong. I had one of the magnito leads going to a 12v terminal on the switch. After frying two coils I got that figured out and got a new coil on. Then I had the coil leads mixed up. I got that fixed and now it runs like crap. It ran fine before I messed with the ignition switch and fried the coils. I took off the flywheel to check the woodruff key and it looks good. See pictures below. I set the point gap (0.02") and put it back together and it still runs like crap. See link to youtube video. So I need your guys help on where I should look to next.

1. Does this damage on the inside of the flywheel look bad?
2. Does the damage to the magneto thingys under the flywheel look damaged?
3. Could I have fried some other part under the flywheel?

Thanks for your time.

http://www.youtube.com/watch?v=EIueA9ceNlQ

 

[Joe Reeves]

Re: '76 Johnson 35 HP backfires PICS

Hopefully you installed new points..... 12v applied there will have them burnt to a crisp.

(Magneto & Driver Coil Alignment)
(J. Reeves)

To align the coils properly, have the metal vertical portion of the coil yokes aligned with the inside edge of the bevel that exists on the top portion of the aluminum seat upon which the coils sit. This creates the proper distance between the coils and the flywheel magnets. Faulty alignment creats friction and the yokes of the coils heat up, turn blue and expand.

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

Set the points as follows. Have the flywheel key aligned with the fiber rubber 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.

Use some 220 wet/dry sandpaper and clean up that magnet portion of the flywheel.

Use some 400, then 600 wet/dry sandpaper to clean up that flywheel taper.

Install a new proper flywheel key and have the flat side of the key vertically aligned with the engine, NOT with the crankshaft taper.

 

[jasper60103]

Re: '76 Johnson 35 HP backfires PICS

Don't run her dry like that, put it in a barrel water.

 

[cbuckla]

Re: '76 Johnson 35 HP backfires PICS

I had muffs on it, but your probably right. I got it in a barrel now. Plus I don't have to turn the water on and off all the time!

I cleaned up the inside of the flywheel and the shaft before re-installing.

 

[cbuckla]

Re: '76 Johnson 35 HP backfires PICS

There is a ground wire going to the stator underneath the flywheel that has been broken for some time, but it ran fine with it broken before. I tried to get the stator off but the last screw rounded out so I couldn't get it apart. Would this have anything to do with it?

 

[rodbolt]

Re: '76 Johnson 35 HP backfires PICS

your ign coils are smoke, you need to repair that ground wire, you need to check the stator plate bushing, looks like the coils and stator plate have been whacking the flywheel.
use lapping compound to correctly fit the flywhel to crank tapers, the key simply lines up the flywheel the taper fit holds it.
if the stator plate isnt grounded the points cant work, if the stator plate bushing is worn the points cant stay adjusted and the magneto air gap cannot be maintained.

 

[cbuckla]

Re: '76 Johnson 35 HP backfires PICS

It ran before without the ground wire. Thats what I don't understand. Everything worked before i replaced the ignition coil (the ones just upstream of the plugs). Are you saying I need to replace those coils under the flywheel?

 

[cbuckla]

Re: '76 Johnson 35 HP backfires PICS

As a follow up...I took the boat to a local mechanic and he said that the lower shaft seal under the powerhead was leaking. He said that this was causing low compression in the crankcase and therefore not allowing fuel and air mixture to be sucked into the cylinder on the down stroke. Does this sound right? I told him not to fix it because it was going to cost more than the motor is worth. How difficult is it to pull the powerhead and replace this seal?