090 Timing

[Spokerider]

Have a question about setting the 090 timing please.

In the manual, it shows a " light box" [ or some other name for it ] to determine exactly WHEN the points close. The light comes on when the points close and the circuit is completed. I understand the theory behind it all.

So, the mark on the flywheel and the notch in the case, when aligned, indicate when the points should JUST close. This will equal the piston being 3.0mm BTDC........exactly where the timing needs to be set.

My question is; why is when I use the multi meter [ one lead on the short circuit wire that has been disconnected from the on / off switch ] and the other lead in ground, I get no discernible difference in the readings when the points are open or closed? I tried different ohm settings and it's the same.....no diff in the readings.

So then I went out and bought a test lamp, one that has 2 AAA batteries in it to power it. It gets hooked up to the saw like the multimeter. The idea being that the light comes on when the circuit is closed. But damn, the light comes on whether the points are open or closed.


The "light box" that stihl uses........how is it different from what I'm using?
What am I doing wrong?

I have it close for sure just by eyeballin the points closing / timing marks aligned, and the saw runs. However, I could easily be a few degrees off with the eyeballin method.

 

[Mad Professor]

Your light/wiring must be shorted to ground and current is not going through the points.

Points may be dirty and multimeter sees an open circuit. Run a piece of clean paper between the contacts with some contact cleaner on it; some new points come with a protective coating.

Did you check the meter by touching the leads together? 0 ohms?

You can always try the rolling paper method if you can hold a piece in the points: place RP in closed points, pull lightly while turning flywheel, paper should slip out of points at/just after timing mark. This works on: trucks, tractors, motorcycles, lawn mowers,........

 

[hotshot]

Did you isolate the condenser (capacitor) or wire?, as all the old school components are wired in parallel

 

[Spokerider]

The points are clean, and I didn't disconnect any other wires.........just hooked the multometer / test lamp up as per the shihl service manual.

It said to disconnect the short circuit wire from the on / off switch [ kill switch wire that goes back to the points ] and connect one lead of the lamp to it, and the other lamp lead to ground. Thats it.

This is the second 090 that I've tried to time, and the same thing happened with the first one too........test light stays on no matter what.

Never tried the paper method. It might be a good plan B however. Thanks for the tips.

 

[Mad Professor]

The points are clean, and I didn't disconnect any other wires.........just hooked the multometer / test lamp up as per the shihl service manual.

It said to disconnect the short circuit wire from the on / off switch [ kill switch wire that goes back to the points ] and connect one lead of the lamp to it, and the other lamp lead to ground. Thats it.

This is the second 090 that I've tried to time, and the same thing happened with the first one too........test light stays on no matter what.

Never tried the paper method. It might be a good plan B however. Thanks for the tips.

Check multimeter first. Open and closed leads on ohm setting. O.K. ?

Does points circuit show open (infinity) and closed ( 0), with points open and closed, on ohm meter? If not there may be a short/bad condenser if 0 ohms with points open.

Check the your wires, points and condenser with the test meter next.

P.S. Rolling paper method always gets me < 1-2 degrees to spec. when I check with a timing light on other engines.

 

[ltm13506.1]

Les points sont propres et je n’ai pas débranché d’autres fils......... Il suffit de brancher le multomètre / lampe de test conformément au manuel d’entretien Shihl.

Il a dit de déconnecter le fil de court-circuit de l’interrupteur marche/arrêt [fil d’arrêt d’urgence qui revient aux points] et d’y connecter un fil de la lampe et l’autre fil de la lampe à la terre. C’est tout.

C’est le deuxième 090 que j’ai essayé de chronométrer, et la même chose s’est produite avec le premier........ Le voyant de test reste allumé quoi qu’il arrive.

Je n’ai jamais essayé la méthode du papier. C’est peut-être un bon plan B, cependant. Merci pour les conseils.

il faut elever le fil qui relie les contact (platiné) pour couper la masse, tester et vous allez voir que ça marche.

 

[Old2stroke]

You have to disconnect the primary of the coil, it's in parallel with the points and it's resistance is so low that most cheap ohm meters can't show the difference between the points being open or closed. Will always look closed. When checking timing, remember the spark occurs when the points open, NOT when they close.