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  • OT - 4 cycle weed trimmers...

    I was looking at some weed trimmers (commercial rating) and noticed that a few manufacturers are now making them with a 4-cycle engine.

    I'm curious if anyone has purchased a 4-cycle model and, if so, do they have a pressurized oil system? I would think that a 4-cycle engine on a weed trimmer would be about the last thing wanted with respect to horsepower/weight and lubrication considerations.

  • #2
    Originally posted by Mike Burdick
    I would think that a 4-cycle engine on a weed trimmer would be about the last thing wanted with respect to horsepower/weight and lubrication considerations.
    But the only thing the EPA will let you sell................

    2 stroke are hated and forbidden because they blow out so much unburned oil and fuel in teh oil-mix versions.

    Making a "real" (non-oil-mix, air scavenged) 2 stroke would be too expensive, and is not done. Or, possibly, the legislation was written without realizing that a 2 stroke as-described would be no diifferent from a 4-stroke type........ and just blanket forbids ALL 2 stroke.
    Last edited by J Tiers; 04-27-2008, 04:50 PM.
    1601

    Keep eye on ball.
    Hashim Khan

    Comment


    • #3
      I got tired of the 2 strokers getting ornery to start and not idling after about 3-4 years, so back in ---00-01?, I think it was, I started doing a little research on the 4 strokers and wasnt too impressed, seemed the carbs were the problem, just couldnt handle an all-position run. Dont recall any mention of oil probs. Anyhow, a few months passed and Ryobi started making noises that they had cured the carb problem and since I was totally PO'd at the current 2 stroke, I bought one.

      I LOVE IT!!

      Weighs a tad more but even after these 6-7 years it'll start on 2nd-3rd pull and will idle perfectly. Has way ample power in any position --- I have to do a LOT of walk trimming with it on its side, and it dont faze it, and living rural I'm constantly fighting vines, -- saw briers (thats a tough brute), poison ivy, virginia creeper, etc, and vines will tell you what a trimmer is made of...

      No doubt they have been improved on even more in the time span since I bought this one
      If everything seems to be going well, you have obviously overlooked something........

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      • #4
        Yep - I won a four cycle about a year ago at a "skills usa" small engine competition. I haven't opened mine up yet, but it weighs 11 lbs and has more horespower and torque at 6,000 rpm than similiar two strokes. (6000 rpm is the "optimum" rpm for most weed eaters. You can rev 'em higher but if you read the manual they tell you not to be full throttle for more than like 5 seconds or something)

        Anyhow, I like the idea. Not significantly heavier and I think they've really thought this one through. Its hard to break into a market that was so dominated by two-strokes and keep your customers happy. I suspect they spent quite a bit of time producing a four-stroke that behaved just as well if not better than two strokes.

        just my humble opinion.

        <edit> actually don't quote me on the rpm ... i can't remember for sure what the figure was but the point is that at the rpm that most two-strokes run for best cutting action had less power than the four stroke did at the same rpm. Basically the manufacturer was just trying to prove that a four stroke could perform as well as a two stroke.

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        • #5
          Have an old ryobi I picked up free a long while ago, 4 stroke, actually runs pretty good.

          It takes quite a bit of abuse without complaint, and to me the best part is the sound.I hate the scream of most two strokes.

          It is not maintained at all, use it once or twice in the spring to clear out the growth near the house and garage, then drain the gas and toss it in the shed till next spring. Most I've done in 8 years is clean the plug and change oil.

          They are more critical of the way they're stored, my old two-strokes I hung motor down from a rafter, the four strokes leak in that position and need to be horizontal or engine up.

          Ken.

          Comment


          • #6
            Originally posted by Mike Burdick
            I was looking at some weed trimmers (commercial rating) and noticed that a few manufacturers are now making them with a 4-cycle engine.

            I'm curious if anyone has purchased a 4-cycle model and, if so, do they have a pressurized oil system? I would think that a 4-cycle engine on a weed trimmer would be about the last thing wanted with respect to horsepower/weight and lubrication considerations.
            Mike,

            To specifically answer your question, no, the oil system on my 4-stroke Toro (at least) is not pressurized. It is "splash-lubrication," like that of most push lawnmowers.

            And I agree with all the other posters. This thing is ten times better than my previous Ryobi two-stroke...easy to start, low maintenance, simple carb, etc, etc.

            Bilal Hassan
            Clarksville, MD

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            • #7
              I guess I am the oddball here I have had a Ryobi 4 cycle for 7 years but I will pick up my 2 stroke every time, I am guessing the reason I have such good luck with it is because I never drain it for winter use staybill in it and also use Bell ray MC1 for the mix.

              My weed eaters are the Q/C type, and I only use the 4 st. one for the tiller tool, and never for the pole saw, it doesn't like being upside down.

              Your mileage obviously differs.

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              • #8
                Originally posted by J Tiers
                But the only thing the EPA will let you sell................

                2 stroke are hated and forbidden because they blow out so much unburned oil and fuel in teh oil-mix versions.

                Making a "real" (non-oil-mix, air scavenged) 2 stroke would be too expensive, and is not done. Or, possibly, the legislation was written without realizing that a 2 stroke as-described would be no diifferent from a 4-stroke type........ and just blanket forbids ALL 2 stroke.
                Hmmm...Stihl still makes a 2-stroke trimmer and a whole lot of other tools...drill, chainsaws... I bought the FS-250. As for lawn mowers, you are probably correct.

                IOWOLF,

                Yeah, I must be "old fashioned" too! I like the 2-cycle since the tool gets put in all sorts of positions as it is used. Hard to believe that the 4-cycle doesn't have a presurized oil system...I wonder how long they will last!

                Comment


                • #9
                  I've seen a techumseh run for three months of regular lawn mowing use with no oil in the case ... It was toast after those three months but I don't think running your little four stroke for a few minutes in a funny posistion is going to hurt it any. Besides, the splasher is likely long enough and the case large enough that at all probable angles of use it is still splashing oil. How often do you use a weed whacker pointed straight at the sky? Think about the range of angles you use it over - its really quite small. There is maybe plus or minus 45 degrees tilt and +/- 20 degrees up/down.

                  Small engines are hard to kill. There's not too much to them really.

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                  • #10
                    4 strokes

                    I looked at a stille sp? about a year ago it was a 4 stroke charging through the crankcase and using a 50/1 gas/oil mix if I remember it gained a slight supercharge effect
                    geno

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                    • #11
                      Originally posted by IOWOLF
                      and never for the pole saw, it doesn't like being upside down.

                      Your mileage obviously differs.
                      Yep, here again, my milage varies.....I got the pole saw attachment, and have used it quite a lot in the 'upside down' position and it doesnt know the difference.....
                      If everything seems to be going well, you have obviously overlooked something........

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                      • #12
                        Originally posted by Mike Burdick
                        Hmmm...Stihl still makes a 2-stroke trimmer and a whole lot of other tools...drill, chainsaws... I bought the FS-250. As for lawn mowers, you are probably correct.
                        My understanding is that it is being "phased in"...... but maybe they haven't noticed weedeaters yet, and some manufacturers are just getting ahead of the curve..

                        I CAN say that I would be happy as a clam if I never heard another screaming 2 stroke weedeater or &^%$# dog-crap blower (leaf blower is what they are sold as). You can hear them for a long way, and all the lawn services use them.

                        They cut the grass, then trim with the weedeaters, and finally blow the trimmings, along with all the crap and dust, back into the yards..... most of the dust ends up a block over. And you can hear them for 3 blocks.

                        A 4 stroke wouldn't fix the dust, but the sound is less grating.
                        1601

                        Keep eye on ball.
                        Hashim Khan

                        Comment


                        • #13
                          We had two Stihl four stroke brush cutters at work. Both suffered catastophic failures. Valves broke off destroying the engine. After some investigation I realized both failures occurred while the unit was being used with a string trimmer head attached. The trimmer line was quite short on both heads. If the trimmer line is allowed to wear down the engine rpm increases dramatically. These little engines will experience valve float which will cause a valve to impact the piston breaking the valve. We went back to the two strokes. I am sure the four stroke would be fine in the hands of someone who has common sense but we have twenty four highschool kids who do our trimming and other such jobs. These kids don't give a damn about equipment . We also had a Honda four stroke and a Red Max four stroke for a while. We found if these units were carried upside down oil would leak out of the crankcase vent and into the air filter. The engine would hydrolock while attempting to start it. Again, trying to tell these kids to carry the unit upright fell on deaf ears. We got rid of the trimmers and went back to Stihl two strokes.

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                          • #14
                            Jcarter makes a good point

                            Like others have said, you need to store a 4-stroke appropriately and they are not high rpm units by nature. Its surprsing, however, that they were not governed. Thats the main reason why 4-strokes are governed is to prevent those kinds of catastrophic failures. To expierence valve float and break a valve you've either got to be hoppin' along incredibly fast (remember these are mechanical, no pump up like with hydraulic lifters) or have some very worn out springs. Maybe they had heat issues before hand that weakened the springs.

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                            • #15
                              With proper design on a small engine like that valve float can be the governor.
                              Free software for calculating bolt circles and similar: Click Here

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