Stihl 038 mag problem

[lone wolf]

Could just be the nature of the beast you know.

[Al_Smith]

The 038's have a pretty good mag so pulling them over slowly still produces a hot  spark .You have to remember it's coming in at 27 degrees advance factory setting .

Pshaw I've been kicked from anything like a 200T up to and including an 084 .That one hurt me though .It got a D-handle after that by George .

[Alta1274]

Now I'm confused. Please explain what you mean by a 27 degree advance. The Stihl spec I read in the manual is talking about an advance of 2.6mm BTC at 8000RPM . That translates to about 2.6 degrees after doing the math since the circumference of my flywheel is 358 mm and obviously there are 360 degrees in the circle. Did you mean 2.7 degrees, or does the ignition module automatically advance the spark to 27 degrees at cutting speeds? What are the 038 engine RPMs at cutting speeds? Seems like a lot of advance.  ???

[joe_indi]

The elasto start system may not be a very good idea if there is more-than-usual lash.
The 'Elasto' bit actually enhances the chances of back fire. A solid grip might be safer.
As part of the cure for saws with this problem changing from Elastostart to plain grip is what I do for customers.

[ZeroJunk]

Now I'm confused. Please explain what you mean by a 27 degree advance. The Stihl spec I read in the manual is talking about an advance of 2.6mm BTC at 8000RPM . That translates to about 2.6 degrees after doing the math since the circumference of my flywheel is 358 mm and obviously there are 360 degrees in the circle. Did you mean 2.7 degrees, or does the ignition module automatically advance the spark to 27 degrees at cutting speeds? What are the 038 engine RPMs at cutting speeds? Seems like a lot of advance.  ???

Several of those vintage saws are in that 20 degree plus range and the timing is fixed to run well at working speed . Newer coils start closer to TDC for easy starting and advance with RPM.

[WidowMaker]

Well I finally decided to take a look at mine.
Air gap was almost non-existant. reset that and now it starts
on the first or second pull, no sign of kick back...

Hope you guys find a simple cure for yours....

[Al_Smith]

To clarify things most chainsaw engines no matter how old they are will be in the 25 to 27degree before TDC spark advance .Some over 30 degree advance believe it or not .--Lombard Comango --

Those listed in MM or fractions of an inch before TDC will still fall within those parameters .I pointed out before on a degree wheel close to top or bottom center the degrees change rapidly because of the relationship geometrically of the crank throw near the bottom of a circle .It gets confusing at times .

[Al_Smith]

More .--This thing shuts you down on a long post so rather than fight it I give in two or three .More than one way to skin the same cat . ;)

So back to 038 mag ignitions .I don't think they are of the self advancing type like the 042 and 048 but rather fixed at 27 before unless the key has been filed or the lamenations altered to shift it .They are  as  I have said a hot coil and it doesn't take much movement or great speed of rotation to get a hot spark .If you dilly dally pulling it over you will get jerked around .

If you think that one is bad try a 2100 Husqvarna some time .

[Alta1274]

The elasto start system may not be a very good idea if there is more-than-usual lash.
The 'Elasto' bit actually enhances the chances of back fire. A solid grip might be safer.
As part of the cure for saws with this problem changing from Elastostart to plain grip is what I do for customers.

Several of those vintage saws are in that 20 degree plus range and the timing is fixed to run well at working speed . Newer coils start closer to TDC for easy starting and advance with RPM.

To clarify things most chainsaw engines no matter how old they are will be in the 25 to 27degree before TDC spark advance .Some over 30 degree advance believe it or not .--Lombard Comango --

Those listed in MM or fractions of an inch before TDC will still fall within those parameters .I pointed out before on a degree wheel close to top or bottom center the degrees change rapidly because of the relationship geometrically of the crank throw near the bottom of a circle .It gets confusing at times .

I hear you all. I have ordered the full 92 page 038 magnum service manual so I can get the factory ignition info for the magnum. I have been working with an older more abbreviated 72 page 028/038  (I assume pre magnum) manual.   I want to see everything the factory has to say about a magnum ignition. Perhaps they might even mention a dwell spec. Which I was apparently mistakenly calling lash since I did it at BDC and did not lock it at 90 degrees with  piston block. When that comes  I can remove the chain, clamp the bar in my shop vice, put a timing light on it to see exactly what I have going on. I am learning more and more from you all and hope to get to the bottom of this bothersome issue if at all possible.
Thanks again all comments are appreciated.
Bob

[Al_Smith]

Well Bob you'd have to have a very fast timing light to see anything because they can wind up to over 12,000 RPM if stock and several more if modified .

[ZeroJunk]

You can Google "how to check chainsaw timing you tube" and you should see one where Brad Snelling does one with a timing light.  But, it didn't look like he revved it up very much. I assumed that whatever advance it had would show up at relatively low RPM since he marked idle and throttled up and there was quite a difference. If the 038 has just a fixed module it should be the same at idle.

[Al_Smith]

Someone else had a vid clip of using a light in addition to Bradley David .I can't remember who or what saw though but it showed a fixed and a self advance type coil .

There really isn't much info on self advancing coils .The only info I have is on the 048 .Even at that I'm not certain if it's a fixed advance or variable with RPM's .It works something on the voltage rise of the trigger circuit which would increase with RPM's . I'd have to read over it again to even attempt to explain it .