Weedeater, Full speed?

Joined
May 12, 2009
Messages
5,532
Location
Canada
I began to wonder about this after the post where the guy burnt out a Ryobi. I have a small, Curved shaft, Weedeater that I have used on our 1 Acre property for 12 years, No problems, only ever changed the trimmer line. No winter preparation just an extra few pulls to get it started in the Spring. The thing is, I never run it full throttle unless the grass I'm cutting requires full throttle! Normally for light grass and and weed stems I only run about 1/3 throttle. Why would the instructions state grass should be cut at full throttle?
 
Joined
Jun 25, 2009
Messages
4,065
Location
Chicago, IL
I can think of no reason unless the unit has a clutch... my Tanaka tends to heat up the clutch alot if I dont run it at higher RPM's. I agree that many people run theirs at less than full throttle. saves gas, noise, wear, vibration
 
Joined
May 25, 2005
Messages
4,009
Location
Calgary Canada
I'm sure if Cujet weighs in he can explain, but if I'm not mistaken small two stroke engines work best a full throttle. I'm not sure if full throttle prevents deposits, etc., but there is a reason. I can't find the thread or the support for this statement but I'm positive I read it here on Bitog.
 
Joined
Apr 22, 2007
Messages
5,215
Location
Houston, Tx, USA
I was just about to say that they work best at full throttle - unfortunately I can't remember why either but this was something I read in a book. I think that it has to do with lubrication of engine parts (since there isn't any crankcase oil). I may be completely wrong about the reasons, but it's best to run a properly tuned 2 cycle wide open.
 
Joined
Jun 24, 2004
Messages
2,898
Location
St. Louis
The man the mows the lawn uses an Echo trimmer with very little throttle. He has been doing this for years with no apparent problem. That is what I do for grass. I just make sure I use the thinner line, otherwise it will only cut at higher RPM's. When I am at my parents I use low throttle for grass and full throttle for brush. That is with an Echo SRM-210. I think running at high RPM's is when the maximum torque is achieved. If it was about lubrication then my 2-cycle equipment should of burned up when idling.
 
Joined
Sep 23, 2008
Messages
9,951
Location
Ontario, Canada
I think the full throttle recommendation comes from a couple different things. Simple carbs are not going to deliver the correct mix at all rpms so you might be running lean or rich... All my manuals say to tune the low screw for good throttle response(which can be a bit lean) and then the high screw for the correct full throttle mix. Also two strokes lean out under load for some reason, so low thottle and medium load can make the motor run lean. So the motor is running hotter with less cooling available. That said, I run my two strokes at part throttle ocaissionally, there's no point in limbing a tree with my 372 WO for 1" branches... For cutting 20" rounds though, I could imagine using half throttle would wear the saw out quicker. Also my lawnboy has run at part throttle 75% of the time for 25 years so I guess if the motor is made for it its fine too...
 
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