Well i had to try....

[Root Rat]

So I purchased a used 20hp Johnson. Not really knowing what to look for apparently I got screwed. Guy said the motor would run his boat at around 23 mph and I was happy to hear that. He started it for me and it sounded ok. Figured I would need to rebuild the carb and put new gas lines. Boy was I wrong. I put it on my boat for a test run at the lake. Full throttle only gave me 1 cylinder that was firing. Not knowing what was wrong I started to pull stuff apart. I found that the magneto was very loose. It shifted front to back around 1/8". So I proceeded to pull more stuff off. I found out the crankcase was slightly broken. The ring around the top portion that keeps the magneto stable was missing on half the casing. I know this means i need to buy a new crankshaft housing but... and this is a big but... I made a new piece at work and fit it, and put JB weld on it. Being this piece shouldn't have any real tension on it I figured if it don't work I was gonna have to buy a new housing anyways...

Wish me luck... lol

 

[RaisedByWolves]

Looks like you did a nice neat job.

Machinist?

I can guarantee you one of two things will happen, it will work or it won’t.


Was going to say I have a spare power head if this doesn’t work, but Hanover is not as close as I thought.

 

[airshot]

Looks like you created a fix for a bad situation. Hope it holds up for you. Lesson learned, always be thorough when buying used, salesmen will tell tou anything !!

 

[thill]

As long as it can withstand heat cycles without popping off, it shoul work well.

Great fix!

Hopefully, that was the actual cause of the ignition issue. Even if it wasn't, that's one less problem moving forward

 

[Root Rat]

Looks like you did a nice neat job.

Machinist?

I can guarantee you one of two things will happen, it will work or it won’t.


Was going to say I have a spare power head if this doesn’t work, but Hanover is not as close as I thought.

Tried my best to keep it clean and tight. Knowing there are moving parts around I wanted to be sure it wasn't going to be in the way.

Not a machinist, though I have access to use a CNC router. So I did measure, draw and cut the part.

So far it worked!!! I was waiting to fix my spark plug cables after the carb rebuild. Once I got it all back together it took about 4-5 pulls and the motor started right up. It was a great sound!!! I was on the lake for about 15 mins just cruising till I ran out of gas... I then had to get the trolling motor and drive my butt back to the dock. The dock was on the other side of the lake.... lol.

It seemd to me I have a power problem when I first power up to get the boat moving. It was very bogged down trying to get moving. Now I'll need to figure that out next.

 

[Root Rat]

As long as it can withstand heat cycles without popping off, it shoul work well.

Great fix!

Hopefully, that was the actual cause of the ignition issue. Even if it wasn't, that's one less problem moving forward

So I used the high heat JB weld. Though after some research the average running temp is well below what I thought and shouldn't cause me any issues.

I had spark on 1 plug. I knoticed the magneto shifted a quiet a bit and I never opened the second point. This was my first option and So far so good. I'll know more in the next couple of trips to test it a couple more times... if anybody else ever has this issue I can send then a half ring. Lol