Aftermarket Electronic Ignition Module Selection

[Jungle Jim]

Need to replace the trigger on my Stihl 032AV electronic and am looking to the inexpensive aftermarket products such as Stens, Nova, Oregon, Atom (brown), Atom (yellow).

There's not a lot of manufacturer information on these and I'm a little confused.

There seem to be two types: a replacement type for points & condenser, and a replacement type for CDI ignitions, the latter being my requirement.

Some of the products carry the warning "not recommended for use with flywheels using multiple magnets".

My flywheel has a magnet on just one side with N and S poles marked - I'm not sure if this counts as 'multiple magnets' in terms of the above. I don't think so but it *looks like* two things & this is all new to me.

Also I don't understand how there can be a 'universal replacement' because this item would surely affect the engine timing and with no way to adjust it. The saw might run but be mistimed. Or are they self-regulating?

Regarding the Atom product, I've read here and elsewhere that the brown one works but so does the yellow one I think the yellow one is what I need but not sure.

There are various reports around the forums of the other brands working or not working. Overall I can't seem to make a definite selection with confidence.

Can anyone set this straight? Thanks much -Jim

 

[KISS]

I hate when i loose everything I type.

Multiple magnets: Happens when you have a generator on the flywheel. Since the crankshaft is not being used to generate the spark, the coil is, you can't be hit with multiple magnet hits.

CDI ignitions are described here: Capacitor discharge ignition - Wikipedia, the free encyclopedia

 

[KISS]

Part II: that I lost.

The module looks like it has an internal cap that can change the timing. Problem is that there are various speed ranges, say 1200 and 1750 for idle speeds for 4-stroke engines with a max speed of about 3600 RPM.

Two stroke engines might have an RPM range of 2000 to 8000.

The sweet spot for timing advance will be different with an overlap hence multiple modules. That assumes that the generated voltage from the coil is the same or close.

What needs to be done, i think, is to relate idle, or designed speed and whether it's 2 or 4 cycle to module color applicatiion.
I would suspect it would come out in the wash.

 

[Jungle Jim]

Module Installed & Working

Part II: that I lost.

The module looks like it has an internal cap that can change the timing. Problem is that there are various speed ranges, say 1200 and 1750 for idle speeds for 4-stroke engines with a max speed of about 3600 RPM.

Two stroke engines might have an RPM range of 2000 to 8000.

The sweet spot for timing advance will be different with an overlap hence multiple modules. That assumes that the generated voltage from the coil is the same or close.

What needs to be done, i think, is to relate idle, or designed speed and whether it's 2 or 4 cycle to module color applicatiion.
I would suspect it would come out in the wash.

Thanks for shedding some light on the subject. I'd really like to see a circuit diagram of these modules but haven't found one anywhere.

I've come to a basic understanding though that they self-regulate somehow, and it's not simply an on / off switching transistor functioning similarly to breaker points / condenser. In the Stihl shop manual though, they say the magneto gap setting will affect the timing. I used the 'business card' method, about .010".

My saw (Stihl 032 AVE) was fixed with the Stens 31 - 9334 module. After using it for several weeks now I must say it is a whole new machine and works better than it ever did before with the older Bosch module. The spark plug is running very clean after a couple gallons of fuel so far. Excellent power. Premium fuel helps a lot too compared to the E10 regular we have around here.

Many other modules, in addition to the Stens, are reported to work in this saw. I hear it works on both points saws and original electronic saws. A number of these modules look like the same one but under different brand names. The Stens says "made in Taiwan" & comes in a plain white box.

Regards -Jim

 

[bigblockburris]

Would you mind posting where you bought it?
I have a 031 that needs the same thing!

Thanks!

BBB

 

[Jungle Jim]

Source For Stens

Would you mind posting where you bought it?
I have a 031 that needs the same thing!

Thanks!

BBB

Try mymowerparts.com

Search by part number 31-9334. The Kawasaki one.

It's been reported this item fixes the 031 electronic but NOT the 031 points / condenser model.

Also your local NAPA store may have some other options.

-Jim

 

[Jungle Jim]

Mounting Your Trigger

Would you mind posting where you bought it?
I have a 031 that needs the same thing!

Thanks!

BBB

Afterthought - whatever module you use to repair the saw be sure to mount it such that it has a good solid ground connection. This is usually through the shell of the module itself via the mounting screw, in which case the best possible place to mount it is to the same cap screw (upper) that holds the magneto coil in place, first being sure to clean the area well. This provides the shortest electrical path (of least resistance) to the common sides of the primary & secondary coils.

If you opt to mount it elsewhere I'd suggest adding a ground wire from your alternate mounting location back to the screw (re above) on the magneto coil. That way the ground path is direct instead of taking the long way around through the case, etc.

I measured 3 ohms difference between the case position mounting of the original Bosch trigger and the above mentioned cap screw on the coil. This is significant when the primary coil -- from which the trigger gets its signal -- measures only 0.9 ohms end to end. Apparently the old Bosch modules factored this resistance in whereas these new aftermarket devices may not.

One other consideration is a mounting that keeps the module from excessive heat which causes failure. Under the flywheel is not good. With the 031 & 032 the top cap screw of the magneto coil IS good in that the fan blows over it. Stihl's original mounting location for the Bosch 1001 module is against the case & outside the fan coverage; not so good either, IMO.

Finally, take care setting the magneto gap which has an effect on the timing. A business card for shimming or .010" worked for my saw.

-Jim

 

[Don Ens]

Anyone know if the Husqvarna 65 or 77 can be converted using a Stens type module? If so, how do you set stator plate for timing?