Timing Retard

[sinkhole]

I have a Johnson 25e74m outboard, which came with an old 14 ft Hourston boat and trailer. My problem is when I set pistons on motor at TDC the set mark on drive shaft cam is well past TDC and piston is on the down stroke, can't retard the magneto plate to align marks as the brass stop is against the shift lever which also works the start safety switch. Consequently when trying to start it just backfires. I should mention motor has 120psi on both cylinders and strong spark also cleaned carburetor. Thanks in advance for any suggestions.

 

[racerone]

Clean the breaker points , set them at 0.020 and go fishing.

 

[saltchuckmatt]

I couldn't quite follow your problem but when most people report back firing it's because they have the wrong wires going to the spark plugs.

Recheck your wiring.

 

[F_R]

I can't quite follow your problem/description. Why are you messing with TDC, and all that stuff? Position the points' rubbing block on the SET mark on the cam and adjust the gap to 0.020". Do same with the other set of points.

If this is mis-understanding your situation, try posting some pictures

 

[sinkhole]

Clean the breaker points , set them at 0.020 and go fishing.

I can't quite follow your problem/description. Why are you messing with TDC, and all that stuff? Position the points' rubbing block on the SET mark on the cam and adjust the gap to 0.020". Do same with the other set of points.

If this is mis-understanding your situation, try posting some pictures

 

[sinkhole]

Thanks for reply. I was concerned that I wasn't explaining problem too well So I'll try again, I actually did what you suggested this afternoon haven't tried to start motor yet. I was under the impression you needed to find TDC first. Using the method you suggest, the rub block on points when aligned with set mark. When observing a screwdrivers travel through spark plug hole to check position of piston it is on the down stroke. Thanks for your help & patience.

 

[racerone]

There is no need to find TDC at all.-----Best to use a meter to set the points if you care to learn.-----Videos on U-tube.

 

[racerone]

Points are set to open at the correct time relative to the rotation of the flywheel magnets.----That has to be to generate the spark.----Timing of spark relative to piston TDC is automatic.

 

[F_R]

Thanks for reply. I was concerned that I wasn't explaining problem too well So I'll try again, I actually did what you suggested this afternoon haven't tried to start motor yet. I was under the impression you needed to find TDC first. Using the method you suggest, the rub block on points when aligned with set mark. When observing a screwdrivers travel through spark plug hole to check position of piston it is on the down stroke. Thanks for your help & patience.

The SET mark on the cam is the high point of the cam and the widest opening of the points. It is NOT when the spark is produced. The spark happens somewhat before that, at the instant the points break contact. Since the spark occurs at approx. TDC, of course the piston will be on the downstroke by the time the SET mark catches up.

 

[davidmbv]

There is a guy who makes a timing fixture. This is what I bought and use a meter to set points.

 

[davidmbv]

Timing Tool | Richard's Outboard Tools

richardsoutboardtools.com

See the webpage for your model

 

[racerone]

The timing tool is nothing but a " dummy flywheel "----You can use the flywheel you have to set points with a meter !----Little extra work , but it can be done.

 

[Crosbyman]