Ignition timing / points gap questions: Stihl 08

[torch]

I am trying to set the timing and new points gap on an 08 concrete saw. I have marked TDC with a dial indicator and marked 0.08 inches BTDC (as per a downloaded service manual). Same manual specifies points gap should be 0.016". I have a buzz box connected to the kill switch wire to precisely locate the moment the points open. The manual also specifies that the edge gap should be 0.24 to 0.35" at that moment.

There seems no way to hit those specs. With the points set to 0.016", and the edge gap set to 1/4", the timing is way advanced. At the limit of adjustment, the edge gap is only about 3/16". To sufficiently retard the timing, the points gap has to be closed down to almost nothing.

At the moment, I've compromised by setting the points gap to 0.012" and leaving the timing somewhat advanced with the edge gap at 3/16". The saw runs, although I don't have any concrete to cut right now.

Any idea what I'm missing here?

 

[Old2stroke]

I am trying to set the timing and new points gap on an 08 concrete saw. I have marked TDC with a dial indicator and marked 0.08 inches BTDC (as per a downloaded service manual). Same manual specifies points gap should be 0.016". I have a buzz box connected to the kill switch wire to precisely locate the moment the points open. The manual also specifies that the edge gap should be 0.24 to 0.35" at that moment.

There seems no way to hit those specs. With the points set to 0.016", and the edge gap set to 1/4", the timing is way advanced. At the limit of adjustment, the edge gap is only about 3/16". To sufficiently retard the timing, the points gap has to be closed down to almost nothing.

At the moment, I've compromised by setting the points gap to 0.012" and leaving the timing somewhat advanced with the edge gap at 3/16". The saw runs, although I don't have any concrete to cut right now.

Any idea what I'm missing here?

Why do you think the timing is too far advanced?

 

[torch]

The timing is more than 0.080" before top dead centre. That is the spec given.

 

[William Balaska]

In all honesty, I've set many and only used a feeler gauge, as there is limited movement in the stator plate, I wouldset the plate up in the middle of the adjustmentand put the flywheel back on and usuallyhave to rotate it counterclockwiseto set the points. I never used the dial indicator, buzz box, etc. I know the manual shows it that way, however the movement of the stator is limited. U can open the points up further than 0.16 from my experience.

 

[KASH]

I assume from your post when you say Edge gap you are referring to the distance from the edge of the coil to the edge of the magnet when the points open.This measurement is for maximum coil saturation.basicaly when the points open a perfect distance will provide the hottest spark.Point gap is not critical with in reason that is why they spec 12 to 16 thou.I have set a lot of older two strokes on snow mobiles by the dial indicator but 90 percent of them now I just set the points as long as some one has not moved the stator.I usually set my new points a couple thou fatter to allow for rubbing block error.Sthil 08s my favorite saw.
Kash

 

[torch]

Yeah, I've had the saw for over 30 years -- before I had a dial indicator and before I had a buzz box. Bought it used, put a set of points in to get it running. All I ever did was set the points gap. But I recently had it all apart to replace the coil, and put new points in at the same time and can't figure out why I can't get things set according to the specs. It's bugging me.

 

[Vintage Engine Repairs]

Edge gap takes priority over points gap. Wider points gap smaller edge gap and vice versa.

 

[torch]

And since edge gap and crank rotation are inextricably linked, timing of the points opening will follow. So adjust the points to suit the timing mark for greatest precision, and the end gap should be in spec?

 

[KASH]

Is the set of points you are installing genuine Bosch ?I have hundreds of pieces of equipment that are points equipped and have been forced to file and reuse all the old sets of points I was to cheap to throw away.The chances of getting a set of OMC outboard points that are a slip in fit is slim to none farm tractors are really bad to.
The big corporations bought out the smaller outfits and about the only ones any good are Blue Streak and Standard and it would not surprise me if they are co owned.
Kash

 

[torch]

Hmmm. Interesting point. (no pun intended) If the arm was slightly longer than original, it would throw the relationship out the window.

I remember seeing Bosch on the coil, but don't recall a maker's mark on the points. Of course, I wasn't looking for one either. I'll have to check.