One magnet vs Two magnets in 1975 25 HP Johnson flywheel?

Acton

Petty Officer 3rd Class
Joined
Jan 15, 2015
Messages
77
I've had my outboard in the shop for the last two weeks that's new to me getting a tune up and a one over. One of the things my mechanic noticed was that the old flywheel on it was cracked so he had me order a new one. My motor is a 25 HP Johnson model number 25R75B, the part number for the flywheel was originally 0581109, which was replaced by 0581792. The 25 HP Johnsons in the 1973-1976 series used the old points and condenser style ignition system. I'm assuming that's why the flywheel has two magnets in it versus one.

Unfortunately I bought a flywheel from a marina that they claimed was 0581792 flywheel, but when it got into the shop my mechanic said it was the wrong one because it only had the one magnet. Come to find out after doing some searching on the internet there are a lot of these flywheels being advertised as being the correct 0581792 flywheel for the 1973-1976 25 HP series motors. I don't think the marina was trying to deceive me either, there's something else going on here with multiple merchants selling this flywheel with only one magnet.

In my case I called the marina back and they did their own research, they pulled the flywheel off of another 25R75B motor they had which DID have the two magnets and are overnight it to me. I've got a camping trip planned at the end of the week.

What do you guys think of this? Are people just lying about what part number these flywheels are on the internet, or are some of these flywheels from that series of motors only supposed to have one magnet? Was it because people converted a lot of those motors to CDI ignition during those years? Anyone have any more info on this topic? Thanks!
 

Chinewalker

Fleet Admiral
Joined
Aug 19, 2001
Messages
8,902
The single magnet flywheels are from the old points and coil magnetos. Your motor has a low-tension magneto with external coils and needs the two magnet flywheel. The single and double manget flywheels are visually similar and if the seller isn't well versed in the ins and outs of the various magneto styles and parts, they're easily mixed up.
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
38,435
Some times the sellers have no clue about what they are selling.------They take motors apart and list the parts for sale.------Almost like reading a comic book sometimes in my opinion.
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
13,642
If you ever see the ignition system when the flywheel is off, don't be surprised when you only see one coil(driver coil) for the ignition system. That's why you need the 2 magnets in the flywheel
 
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