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Stihl's 4 mix engine?

Discussion in 'Chainsaws and Power Equipment' started by Marshel54, Jul 13, 2017.

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  1. Kg461

    Kg461

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    I agree. Ive had my BR 600 10yrs now and I disassembled it, cleaned valves, installed new rings and bottomseals, and a new plastic cam gear. I keep a regular check on the valve adjustment and run Red Armor @ 40:1 and not as much as a single glitch since
     
    Kg461, Aug 4, 2017
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  2. RCBS

    RCBS

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    IMO extra torque is about all the 4-mix has to offer. Have used a friends trimmer before...do not know the model #. It was a little cantankerous to get started, but ran fine after. The main issue I had was that the trimmer weighs 3 pounds more than what I'm used to. That's quite a bit of weight for the extra .25hp it produces. My friend has told me although he has been satisfied with the trimmer (think he's had it for 4-5 years), he wouldn't buy one again. I do not believe he has had any reliability issues with it. He doesn't like the weight either. He trims around probably 60 trees, a 200' long, 6' bank along road edge and several out buildings spread over 4+ acres. Weight becomes significant when dealing with that much trimming.
     
    RCBS, Aug 4, 2017
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  3. Kg461

    Kg461

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    1. I have been inside a fs 4 mix motor vs a simple fs250 . Less moving parts, no plastics internally is what a fs250 has compared to fs 4 mix motor
     
    Kg461, Aug 4, 2017
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  4. clemsonfor

    clemsonfor

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    Plastic cam gear:eek:. Why not brass , aluminum or some other soft metal? Cost I guess, save the $2
     
    clemsonfor, Aug 4, 2017
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  5. Kg461

    Kg461

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    They really do hold up well though to be plastic and pretty simple to change.
     
    Kg461, Aug 4, 2017
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  6. Kg461

    Kg461

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    Screenshot_20170804-123852.png
     
    Kg461, Aug 4, 2017
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  7. RCBS

    RCBS

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    Cost and weight savings.
     
    RCBS, Aug 4, 2017
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  8. MasterMech

    MasterMech The Mechanical Moderator

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    The 600s blow when the blower tubes get all discombobulated and the airflow from the blower is incorrect. Some guys run the nozzle way down actually on the ground allowing them to overrev big time. They aren't bulletproof but properly cared for they will hold up.

    Granted my BR6 only does my lawn for the most part. But it's lighter, quieter, more comfortable, and drinks a helluva lot less fuel than the equivalent or bigger RedMax/Husky blowers. Works for me. (And yes, I have one of the first year production BR6s that were especially problematic.
     
    MasterMech, Aug 4, 2017
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  9. MasterMech

    MasterMech The Mechanical Moderator

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    Metal is not always superior. Many plastics now exceed the strength of cast aluminum/mag/zinc parts. Now that cam gear would likely be a sintered powered metal part if it were made from something metallic and that presents its own problems with complex shapes.
     
    MasterMech, Aug 4, 2017
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  10. clemsonfor

    clemsonfor

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    Yea it looks durable for its application I guess. Heck first thing I thought of was automotive. Wasent it some GM from the 70s or 80s Mabe 90s??? Had nylon cam gears.
     
    clemsonfor, Aug 5, 2017
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  11. OldJack

    OldJack

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    OldJack, Aug 5, 2017
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  12. MasterMech

    MasterMech The Mechanical Moderator

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    Plenty of them did. The Mark IV big blocks from the 80's with finned timing chain sprockets were the ones notorious for failing. Gen V ('91+) went to a different style sprocket, metal hubs, solid nylon sprocket teeth which didn't have problems like the older engines.
     
    MasterMech, Aug 5, 2017
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  13. clemsonfor

    clemsonfor

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    i think these were the ones i was thinking of. i just remember it was older cars of a certain vintage when i worked at the parts store
     
    clemsonfor, Aug 5, 2017
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