67 40hp Flywheel lost magnetism?

C

cdentii

Cadet
Joined
Jul 9, 2009
Messages
10
Hello, First off this is my first post. I have a 67 40hp Johnson Sea Horse RDS29 electric start, just picked up the boat, motor and trailer for a bargain, motor would not run so after replacing the plugs I found a stripped out plug and installed a heli coil and plugs and have good compression in both cylinders, good fuel delivery ect... got the motor to finally start and had a miss so I checked the spark and no spark in the lower cylinder expected to find either a bad set of points, blown coil or wire. I pulled the Flywheel off (and what fun that was) Checked the magnets out and the larger/longer one has no magnetism at all, the other seems fine, Just to verify are both supposed to have magnetism or is one just for a counter weight? I am mechanically inclined however magneto systems are new to me, any ideas, thoughts ect....:confused:
 
W

wilde1j

Vice Admiral
Joined
Apr 15, 2002
Messages
5,964
Re: 67 40hp Flywheel lost magnetism?

Pulling the flywheel should have been easy. Did you use a harmonic balancer puller with Gr8 bolts and washers?

Dealers can order a magnet kit (which I think comes with epoxy) to fix the magnet deal. No counterweights I'm aware off.

When reinstalling flywheel, make sure the mating tapers are clean and dry (no oil) and make sure to torque to the correct value with a torque wrench.
 
F

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Re: 67 40hp Flywheel lost magnetism?

cdentii said:
Hello, First off this is my first post. I have a 67 40hp Johnson Sea Horse RDS29 electric start, just picked up the boat, motor and trailer for a bargain, motor would not run so after replacing the plugs I found a stripped out plug and installed a heli coil and plugs and have good compression in both cylinders, good fuel delivery ect... got the motor to finally start and had a miss so I checked the spark and no spark in the lower cylinder expected to find either a bad set of points, blown coil or wire. I pulled the Flywheel off (and what fun that was) Checked the magnets out and the larger/longer one has no magnetism at all, the other seems fine, Just to verify are both supposed to have magnetism or is one just for a counter weight? I am mechanically inclined however magneto systems are new to me, any ideas, thoughts ect....:confused:
Click to expand...

Well, I suppose all things are possible, but it is a pretty safe statement to say that the magnets used in outboard flywheels since WWII simply do not lose there magnetism. At least not by themselves. There are two magnets cast into one side of the flywheel. Both should have magnetism. There is also an aluminum dummy "bump" (counterweight) on the opposite side which obviously is not magnetic. I don't know what a guy would have to subject the magnets to to make them non-magnetic. A de-magnetizer?? Attempting to recharge them backwards??
 
C

cdentii

Cadet
Joined
Jul 9, 2009
Messages
10
Re: 67 40hp Flywheel lost magnetism?

wilde1j said:
Pulling the flywheel should have been easy. Did you use a harmonic balancer puller with Gr8 bolts and washers?

Dealers can order a magnet kit (which I think comes with epoxy) to fix the magnet deal. No counterweights I'm aware off.

When reinstalling flywheel, make sure the mating tapers are clean and dry (no oil) and make sure to torque to the correct value with a torque wrench.
Click to expand...

Thanks for the info, yes I did use a harmonic balancer puller it still was a tough one. The magnet is cast into the flywheel in order to install a kit with expoy the magnet would need machined down for clearance.
 
C

cdentii

Cadet
Joined
Jul 9, 2009
Messages
10
Re: 67 40hp Flywheel lost magnetism?

F_R said:
Well, I suppose all things are possible, but it is a pretty safe statement to say that the magnets used in outboard flywheels since WWII simply do not lose there magnetism. At least not by themselves. There are two magnets cast into one side of the flywheel. Both should have magnetism. There is also an aluminum dummy "bump" (counterweight) on the opposite side which obviously is not magnetic. I don't know what a guy would have to subject the magnets to to make them non-magnetic. A de-magnetizer?? Attempting to recharge them backwards??
Click to expand...

Thank you for the info F R,
The era would be more like Vietnam (LOL) still yes it is old none the less, just to clarify the "Smaller Magnet" is actually 2 magnets (which is strong enough to pull the flywheel when attached to a screwdriver) and the other "Larger" (opposite side) (which will not stick to anything) is actually an aluminum counter weight? It is kind of hard to tell as they look so very much alike other than size. so if you could let me make sure I have this correct, On a 2 cylinder magneto in the flywheel there is a magnet that chargers both of the coils as it rotates and on the other side there is a counter weight. Correct? If so then my flywheel is good.
 
F

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Re: 67 40hp Flywheel lost magnetism?

cdentii said:
Thank you for the info F R,
The era would be more like Vietnam (LOL) still yes it is old none the less, just to clarify the "Smaller Magnet" is actually 2 magnets (which is strong enough to pull the flywheel when attached to a screwdriver) and the other "Larger" (opposite side) (which will not stick to anything) is actually an aluminum counter weight? It is kind of hard to tell as they look so very much alike other than size. so if you could let me make sure I have this correct, On a 2 cylinder magneto in the flywheel there is a magnet that chargers both of the coils as it rotates and on the other side there is a counter weight. Correct? If so then my flywheel is good.
Click to expand...

There is one pair of magnets on one side. There is an aluminum couterweight on the opposite side. As the magnets go past the forward-most coil, it produces a spark for the top cylinder. Then the wheel turns 180 degrees and the magnets go past the rear-most coil and produce a spark for the lower cylinder. (Alternate-Firing Twin)
 
You must log in or register to reply here.
Top