031 flywheels - measured!

[Lakeside53]

I promised someone on AS that I would measure the difference between the 031 Points flywheel and the Electronic flywheel.

There are a couple of different styles of Electronic wheels but they are interchangeable. The version I'm showing here is that with the points covers, but if you look at the bottom left, it has a symbol that represent it as electronic.

I photographed the wheel "in plane" so there was no distortion, fed them in a background layer in Visio, and used the cad functions to perform the measurements. The leading edge of the N magnet was used as an index for measurements relative to to the key slot.

There has been a lot of AS discussion of whether you can just replace the points with a module whether you need to "reverse legs" on one, etc etc. I don't know the definitive answer, but if you get it wrong, even though the saw "runs", the timing is way off.

If I have time in the next few weeks, I'll runs some tests with points and different modules/flywheels, and use a timing light to show the results.



Points version:

Electronic version:

 

[motorboy]

That is far more offset than I thought it would be! I am surprised the 031s with the timing that far off even run.

 

[Lakeside53]

Stihl sent out a warning in the early days that using a conventional module without changing the flywheel could result in a muffler glowing red...

 

[motorboy]

I am beginning to think that I am going to stick with the orginal points system. My points are fine, and I can still get a new condensor. I will think it out more when I get to the ignition on my project. I am still working on the crankcase of my 031, looking on ebay for a used crankcase half and flywheel.

 

[stihltech]

timing

I know that with a Stihl module, you must change the flywheel, and at is why I quit using them. The atom and new generation modules do not have this problem. They are made to relpace points and condensor. There is a certain module for electronic module replacement only.
I have installed them for 15 years. Probably put in a hundred. No glowing mufflers, and every customer was impressed with the way the saw started and ran.
But, you must use the correct module for points or electronic.

I don't mean to be a pain, but I have the correctly running saws to prove it.

 

[Lakeside53]

StihlTech - No pain here!! I fully believe you when you say some are fine.

Can you list some of the currently available modules that to your knowledge do work. It will help out some of those who are uncertain, even me. I'll get some and throw a timing light on them with differing setups.

I'm pretty sure I know why some modules can be made to work correctly the 031 (as different from say the 032 which has none of these issues when converting from points using Atom, Stihl or Nova), and others don't. I want to do some real measurements - it has to do with which magnet edge they are forced to trigger on, which is why trigger polarity-reversal comes into play (points have a much wider window as the magnetic flux build is only discharged when the points mechanically open). The Stihl Trigger module grounds though its metal case which makes it difficult to reverse, but I bet if I isolate it, it might just work the same. The triggers are all pretty simple inside.

 

[1953greg]

stihltech

"There is a certain module for electronic module replacement only."

is there one available for the 041? if so, bout how much are they? if the points are ok then should one switch? advantages?

 

[stihltech]

modules

I am using the Nova's now, no problem so far. The best module is the orange Atom, which I don't seem to be able to get anymore.

Anybody know where they are available?
You are correct on the Stihl module, because it is not intended to replace points.
The models I put them on are mostly 028 and 031. I believe I have done 032, but points versions are very rare here. The orange module replaced the under flywheel module.
lots of XL 12 and 10 10 Macs. Other various brands also.
Not one complaint. They are a savior on an 015.

 

[Lakeside53]

I'm using Nova for generic replacements, but also the Stihl module. Are you reversing any connection on the Nova for the 031?

 

[stihltech]

flip flop

Yes, that really affects the timing.

I do want to see what setup you use to check timing. I have a certain vintage saw that I am in need of timing advance measurement.

041, I would not bother converting. Those points and condenser are bulletproof. 031 was a problem child. Actually quit selling the points version due to problems.
Now remember, this is before 028 came out.

 

[JohnO]

Here's another comparison of the points vs. electronic flywheels. In these pictures, the electronic is on top of the points version, with the keyways lined up. You can see that the magnet offset almost causes the south magnet of the electronic flywheel to line up with the north magnet of the points version. Does this have something to do with switching the wires on the nova/atom modules?






-John

 

[Lakeside53]

Yes.. That my working theory that I'm going to validate on a scope and timing light - on my list of projects. It's what I was suggesting in an earlier post, but your pics shows it well.

By reversing the leads you are triggering off the leading edge of the other magnet. I'm sure sure how "exact" that is, but it's probably close enough.
I believe the stihl module can also be "reversed", but as the case is one of the leads, it's not as easy.. I'm going to test that also. The modules are pretty simple inside... no "smarts" like the modern integrated coil/trigger.


I'd like to see comparisons of 032 flywheels - points and electronic. These seem to work just fine when converted without flipping connection etc.

 

[BSchmidt]

Electronic ignition

This is the workings of electronic ignition

 

[Fish]

Good to see Andy posting again........

 

[flyboy]

Great work Andy.

I tried the Nova in both directions. The timing was WAY off. The spark was not as hot either.

My solution was to reverse engineer the condenser/capacitor at work using about $50k worth of electronics equipment. I was able to find a modern replacement cap with the same or better specifications. They are made by Wima, and are less than $1 ea.

Search AS for "Wima" and you will find plenty of posts on it. A few others have tried them as well with 100% success.

 

[flyboy]

I would love to see your timing setup. I have played with the points gap on one of my 031s to advance the timing. At 0.018" it has a hard timing revving up. 0.016" works quite well.

 

[BSchmidt]

electronic ignition

This is the workings of electronic ignition

This is very close to what stihl uses (bosch)

 

[Biker Dude]

I'm doing the electronic conversion on my 031 and had a little time this morning so I merged the 2 images so you can get a good idea of how much to move the key way.

 

[flyboy]

Just out of curiosity.....WHY?

Points units will run for the better part of 30 years with minimal maintenance. Electronic units do not burn as hot, especially at low (starting) RPM. I converted one of my 031s and then quickly went right back to points.

Modern saws may acknowledge/fix these shortcomings, but the after market electronic modules do not.....in my experience.

 

[Biker Dude]

Did you alter the timing when you switched over to electronic?

I did it for a few reasons. I like messing with stuff just to gain knowledge and experience and I think points suck compared to electronic ignition. When I switched my Ironhead Sporty to electronic ignition it ran smoother, started better, and had better power than it did with points. Finding an original Stihl condenser would be impossible and just getting access to the points is an ordeal on an 031 so hopefully I won't ever have to mess with it again. I'm going to put the module in the airbox so if it does go bad it's a 2 minute job to replace it.