Tepramental and Idiosyncratic Chain saw @GRRRRR.com

cathead

CATWERKS LTD
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Feb 7, 2013
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I have this older Stihl 028 WB chain saw that has points ignition. It has been running poorly and it surely is an ignition
problem. Also, I have cleaned any oxidation visible under the coil and points with no success. It runs but misses erratically
at any engine speed. I have replaced the spark plug, the capacitor, and the ignition coil and the same malady lingers on.
I have had the flywheel off a dozen or more times using my home made flywheel puller so finally set it aside and decided to
vent on Hobby Machinist.

On a different note, more along the lines of machining I am including a photo of the flywheel puller I made for Stihl saws.
It was a while ago that I made it and I remember the the threads on the flywheel are metric and my lathe does not do
metric threads. I used the closest thread pitch to the metric threads and the flywheel tool threads on about two turns before
binding. Fortunately it has enough thread purchase to pop the flywheel off.

P1020770.JPG
It's a fun and somewhat challenging project if a person has a need for such a tool.


While I was at it I took a photo of the saw and the parts I have replaced. It's been a good saw but this has me somewhat perplexed.
I'm gonna sleep on it and give it another go in the morning. One thing I did notice is that the key for the flywheel doesn't stick out
much on the crank, leading me to believe that possibly the flywheel is moving back and forth a little on the crank. I have another
parts saw so will look through my parts and see if I have a spare key. Other than that, there isn't much left. I have cleaned the points and adjusted them so pretty much have ruled out the possibility that the points are faulty.
P1020769.JPG

The newer Stihl 028 saws have pointless ignition systems, apparently some sort of CDI "capacitive discharge ignition" and there are
aftermarket CD chips to replace points setups too. I have tried those and the ones I had worked a while and eventually failed completely.
I'm open to any ideas anyone might have concerning this :rolleyes:perplexity....
 
My 028 WB is about 25 years old and still cuts great. A while back I did have to replace the gas lines because of performance issues and she's good as she can be.
 
My Poulon would run good with a full tank but as the level dropped a crack in the fuel line was available to air inclusion and= crappy run. New fuel lines and runs as good as it ever did, notice I didn't say it ran great because it is a poor excuse of a chain saw but was free so what the heck.
 
Thanks for all the responses. I'm pretty sure it is spark related but will look at the fuel lines and carb as well to
get to the bottom of it. Apparently the newer saws have a CDI built right into the coil because it looks like just
a coil and flywheel magnet. The CDI must be hidden in the coil apparently... I have other saws but it would
be nice to have this one running right.
 
Do you have a magnet under the flywheel for the ignition?
 
Totally unrelated saw
I just repaired a homelite saw from the 80’s
It had an early prestolite CDI pointless coil that is heat sensitive
Apparently if the saw is used out of normal position for long periods of time, could induce a miss-or stop spark altogether.
My dad gave me the saw 10years ago, it stopped running 2 years ago allofusudden.
I pulled it apart enough to pull the coil out.
I looked for upgrade coils and didn’t have much luck. I did find a site for a guy who loves the old homelites and he suggested baking the coil at 225*F for 20 minutes.
The coils insulation is somehow rejuvenated and it may restore operation.
I was a non-believer until I tried it.
Long story short, it runs like a top again
 
When I worked on Mercury outboards, with a magnet was involved, and the magnet got weak it would cause a miss, also poor coil grounds....
 
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