Author Topic: Stihl 4-mix engines : how to set tachometer : 360 or 720 ??  (Read 383 times)

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Offline flatsix

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Stihl 4-mix engines : how to set tachometer : 360 or 720 ??
« on: December 19, 2013, 12:43:25 pm »
Hello,

Does anybody know how many Sparks/revolution of the crankshaft ?

Normally I think the 4-mix motors act like a 4-stroke, thus: 1 spark each 2 turns of the crankshaft = 720

I bought a tachometer TT20 , and I wonder which setting to apply for reading correct rpm : is it 720 or 360??

Thanks,

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Offline Cut4fun

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I steer clear of these. But willing to learn something new.  Searching for info.  I'm thinking like you 720

copy paste = The STIHL 4-MIX Motor runs in comparison to the common 4-stroke engine with the usual petrol-oil mix (1:50). The 2-stroke mix is distributed through a bypass channel to the enginer and thus ensures complete lubrication.

http://youtu.be/eWZfRdm9u9c
REDNECK Saw Repair

Offline Cut4fun

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Offline flatsix

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In a week or so I will have my tachomter. It is adjustable for 720 - 360 - 180 - etc.

When it is there I will give it a test to see witch setting it must have - I think 720 (1 revolution each 2 turns)

When I know I will post the result.

Thanks anyway for your feedback  ;D

Offline 660magnum

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The four mix spark plug fires every time the piston passes TDC just like on a B&S
We should share what we know... someone may learn...
That knowledge can live after us... and that "Pays It Forward".
Be all that you can be . . .

Offline flatsix

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What does that mean for the tachometer?  Should it be set at 360 or at 720 to read the right amount of rpm? ???

Offline Eccentric

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What does that mean for the tachometer?  Should it be set at 360 or at 720 to read the right amount of rpm? ???

Set it for 360.
-Aaron

For older saws:
Tune the H side so that it 4-strokes (burbles) at WOT unloaded and just cleans up when under load.
When you lift cutting load, the saw should immediately revert to 4-stroking.  Fine tune the transition point for the wood you're cutting.

Offline flatsix

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O.K. I'll do that ! ;D

 

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