Having a timing issue with a 71 25hp johnson outboard

[JustJiggin]

I just had to run a new wire that run up under the flywheel where the points and condensers are. The wire that broke connects to a wire that leads to my kill switch. Anyway the wire got wore real bad and ended up breaking just before it went under the flywheel. So I had to remove the fly wheel to get to the wire. While I was at it I cleaned the points and checked everything out on the armature plate. I have the 71 25hp Johnson and I was looking online it seems my motor should have two coils under the flywheel. Mine only had ONE? Now that I think about I could see where another coil was supposed to be. I guess who ever had the motor before me did some work on it. But it sure threw me for a loop. Or maybe I'm wrong about it having two coils where the points and condensers go? Could somebody verify that for me please? The motor still ran very good with the one coil I would have never knew if I didn't have to remove the flywheel to fix that wire. Anyway back to original question after putting everything back together and setting the points to .020 with a gauge, and putting the flywheel back on. I try to crank it and BOOM back fired, it never back fired before. It backed fired several times while trying to crank it. I got the two external coils (not the plug wires but the wires that run to the coils with the plug wires) wires mixed up. I disconnect them and switch the wires and it cranks up. I still have a back fire but it does start up and will run WOT but I know timing can't be a 100% cause it wasn't back firing before I took flywheel off. I do have moon key in the slot so it's not the moon key on shaft. I've been reading about cam timing and timing marks on the flywheel can someone explain a little more in depth about the timing and the flywheel. I really need to get the timing back in time tomorrow. I just put flywheel back on I wasn't aware it had to be timed once you removed it.

 

[JustJiggin]

Re: Having a timing issue with a 71 25hp johnson outboard

I'll double check all my wiring tomorrow to makes sure nothings wired wrong but I don't believe it is.

 

[brim_buster]

Re: Having a timing issue with a 71 25hp johnson outboard

The flywheel is notched to fit the key way. I highly doubt its out of time. Sounds like a carb or elect. problem. The flywheel only goes on one way and you can turn the shaft all you want and the flywheel is still gonna go on only one way. Id look for your problem somewhere else other than timing. You normally only have to re-time if you tore the powerhead down.

 

[hardwater fisherman]

Re: Having a timing issue with a 71 25hp johnson outboard

i think you should check the year of your motor. in 71 the coils where under the flywheel. i think 73 was the first year with external coils. thats why you have only one under the flywheel it is called a driver coil. do you know the model number?

 

[F_R]

Re: Having a timing issue with a 71 25hp johnson outboard

I have to agree with hardwater, you don't have a 1971. You have a 1973 or later with the Lo-Tension Magneto. Driver coil under flywheel and two external coils.

If you have the wires between the points and external coils swapped, it will be 180 degrees out of time.

If you have the breaker cam upside down, it will be 180 degrees out of time also.

Improper breaker points adjustment will make it out of time also, but not so severely.

Improper adjustment of the relationship between the brass cam and throttle linkage will mess up the idle and may cause sneezing.

Did you have the tapers clean and dry and use a torque wrench to tighten the flywheel nut to 40-45 fi lbs? If not, it may shear the key and ruin the flywheel and crankshaft.

 

[JustJiggin]

Re: Having a timing issue with a 71 25hp johnson outboard

Yall are correct it is indeed a 73 I looked at the diagram online and it matches mine...

 

[JustJiggin]

Re: Having a timing issue with a 71 25hp johnson outboard

Are you talking about the brass ring under the armature plate F_R? If so how do you know its in sync?

 

[racerone]

Re: Having a timing issue with a 71 25hp johnson outboard

The brass ring under the armature plate has nothing to do with timing.-----There is a cam that opens the throttle at the correct time and that is often adjusted because it looks wrong.----Throttle plate must be closed when idling.

 

[F_R]

Re: Having a timing issue with a 71 25hp johnson outboard

This is a generic drawing, but shows the cam I spoke of.

 

[JustJiggin]

Re: Having a timing issue with a 71 25hp johnson outboard

Thanks F_R and everybody else I got it tuned up nicely. Points where gapped to far apart after farther inspection. I'm getting a big blue flame at the plugs now and no back fire when cranking.

 

[oldman570]

Re: Having a timing issue with a 71 25hp johnson outboard

Here is a Link to give you more ways to set the points on your motor.
Johnson
I have used the info on a 1976 Johnson 25 HP, which has the same basic system as yours, and the static timing using a ohm meter, has worked best for me. The article has plenty of good info and makes for fine easy to use reading.
F-R was making a pointer that went in place of the flywheel for some motors that also made it easier to set the points also. A PM to him to see if he still has one to fit your motor is worth the short time it takes, and an other way to get the points set easier.
JMO
Oldman570