Stihl 280C with M-Tronic (sort of)

[eiklj]

I tore into a fairly new 280C yesterday becuase it would die if you touched the throttle. The high side of the carb is controlled by the same contraption that controls the entire carburetor on the 441 M-Tronic. The 280's carb allows adjustment of the low side and idle speed, the 441 does not.
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[eiklj]

Here's a couple of close-ups showing the same solenoid/actuator/thingy that meters the high side. The limiter cap was a PITA to remove from the low side, but I did and was necessary to adjust out the problem.
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Arrows show the low side and idle speed adjustments.

 

[TK]

So it's an M-Tronic that you adjust?? Kinda defeats the purpose, no?

 

[eiklj]

I was finally able to fix the problem (I think) by dropping his idle speed down. Not sure if someone may have messed with it prior to me working on it.
Here's my theory: The idle speed was increased to the point that the high speed solenoid was controlling the carb such that if you touched the throttle trigger, the low speed circuit was not working correctly and the saw would sputter and die.
Hope that made sense. I was by myself and not able to shoot any video of what was happening.
Anyway, by allowing some adjustment, I was able to fix it (I hope).
If this would have been a full M-Tronic controlled carb, I wouldn't have ahd any issue at all as the solenoid would've controlled the entire carb, not just the high end.
Now my question:
Why would Stihl (or anybody) offer a halfway version of electronic carburetion? Wouldn't the cost of manufacture be the same for a ½ M-Tronic as for a full blown M-Tronic?
More pics to come...

 

[eiklj]

This saw is confusing to me. It's not a pro saw, it may be a farmer/rancher mid range saw, but has too many homeowner features that make it a bit squirrely.
The first feature is a larger version of the quick change chain tensioner doo-dad that sort of works. I'm still not a big fan of these although some customers really like them.
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[XSKIER]

Isn't AutoTune more similar to your MS280C than M-Tronic?

 

[eiklj]

And the second feature that I really feel is unecessarily over-engineered is the chain brake dead-man whatchamacallit. When your hand leaves the dead-man, the chain brake is set.
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The first pic shows the dead-man switch down and the cable pulling the brake band linkage to relaease the brake. If you want to sharpen your chain while still on the saw, you must pull the choke/start/stop lever all the way down to the choke position as shown to release the brake.

The second pic just shows the dead-man released and the brake set.

Takes some getting used to if you've never messed with one of these goofy things. Not bashing Stihl. I like Stihl and that's about 85% of what I work on. I just think it's more over-engineered gadgets to appeal to a wider range of consumer. (flippy caps)
Maybe we'll see more of the hybrid saws in the future that don't fit neatly into one specific category.
Anyway, I thought I'd share. Let the comments commence...

jason

 

[eiklj]

Isn't AutoTune more similar to your MS280C than M-Tronic?

I haven't tore into an AT yet, hope to soon. If I do, I'll certainly post pics.
We've only got one AT (562, I think) in the shop because of the hot start issue but it went back to the factory before I had a chance to get my hands on it.

 

[TK]

This is nothing like AT.



The chainbrake feature is an interesting concept. I wasn't aware that was how it worked. I could sell a lot more saws to husbands with overly protective wives with that feature :cool2:

 

[eiklj]

So it's an M-Tronic that you adjust?? Kinda defeats the purpose, no?

My question too.