1955 Johnson 25 electric start - no piston markings on flywheel?

[livinfulltilt]

Im currently working on a 1955 Johnson 25hp electric start (RDE-17 I believe?). I found a great video on youtube from a gentleman who shows how to fine tune the points on these motors (something he learned from here on iBoats). In his video, the flywheel has a marking for each piston that corresponds to the markings found on the magneto assembly (correct term?). Im sure many of you have seen this video, but in case you have not, he adjusts his points to open when each piston mark is between the two markings on the magneto assembly.

I am not sure if I am just missing something obvious here, but my flywheel does not have any markings to indicate piston position. I do have the twin markings on the magneto assembly, but that is all. Did I miss something obvious here? Or do I just set the points to .020 and reinstall the flywheel, double check points gap and nothing further?

I just installed new coils, and cleaned and transplanted a set of points and condensers from a donor. Figuring this out is literally the last thing on my list before reassembly and an attempt to start her up. Ive learned a great deal of maintenance and repair info from this forum and I appreciate the help you have all contributed from time to time!

Thanks in advance for the help on this!

 

[livinfulltilt]

Re: 1955 Johnson 25 electric start - no piston markings on flywheel?

Just went back out to check again, and I found them. They were very small notches in the downward facing surface of the flywheel. If you don't mark a vertical line on the side of the flywheel prior to reinstalling it to set your points, you would never see them. I just used a black sharpie to color them in and draw a vertical line extending up the side of the flywheel so they are easy to see while doing the fine tuning.

Hopefully this will help others who don't have the cast ridges on the sides of their flywheels...

 

[lindy46]

Re: 1955 Johnson 25 electric start - no piston markings on flywheel?

F_R makes a tool for setting points using those marks. I've always just set the point gap to .020"using a feeler gauge. Set points when the rubbing block on the points is at the high point on the cam.

 

[livinfulltilt]

Re: 1955 Johnson 25 electric start - no piston markings on flywheel?

One thing that I still don't really understand is how that little wheel is set properly. I know it opens the rear throttle plate in the throat of the carb, but what is the proper way to set this? I plan on picking up a few new springs for it this afternoon since it appears the old spring may be starting to lose their "pull" and occasionally this wheel likes to stick in an outward position with no contact against the metal edge it is supposed to contact.

Ive read various things that say it is supposed to *just* start to open the throttle plate as soon as the tiller handle passes the *shift* mark, and ive also read that the wheel is supposed to start opening the throttle plate once the wheel is aligned with the 2 timing marks on the magneto assembly and so on. Which is correct? Also, if someone could explain how to set this without referencing marks on my tiller handle? I am temporarily using a homemade tiller handle that has no markings until I can find a replacement handle. Please note that I have full throttle range with this tiller, so I can go from idle to wide open with no issues to set this motor up.

Thanks!

 

[jbjennings]

Re: 1955 Johnson 25 electric start - no piston markings on flywheel?

One thing that I still don't really understand is how that little wheel is set properly. I know it opens the rear throttle plate in the throat of the carb, but what is the proper way to set this? I plan on picking up a few new springs for it this afternoon since it appears the old spring may be starting to lose their "pull" and occasionally this wheel likes to stick in an outward position with no contact against the metal edge it is supposed to contact.

Ive read various things that say it is supposed to *just* start to open the throttle plate as soon as the tiller handle passes the *shift* mark, and ive also read that the wheel is supposed to start opening the throttle plate once the wheel is aligned with the 2 timing marks on the magneto assembly and so on. Which is correct? Also, if someone could explain how to set this without referencing marks on my tiller handle? I am temporarily using a homemade tiller handle that has no markings until I can find a replacement handle. Please note that I have full throttle range with this tiller, so I can go from idle to wide open with no issues to set this motor up.

Thanks!

\

the part in red bold is correct. The plate should just start to open as the roller passes the mark on the throttle cam. I find the tiller shift/slow/start markings to be almost useless.
Honestly, I've never seen those springs "too weak". They either break or work. I would be suspicious that something else is binding on your throttle plate. Maybe trash or whatever in the plate shaft bores. Those throttle plate shaft bores can get wear and actually provide a vacuum leak if they're bad enough.
Double check for the cause of the binding.

 

[livinfulltilt]

Re: 1955 Johnson 25 electric start - no piston markings on flywheel?

Found the issue with the roller, was just a simple cleaning of the rod that it pivots on. A little cleaning, a little grease, and a little extra bend in the spring fixed everything right up.