Overheating strimmer. Normal, or user error?

New to these forums, so hello to all. I made a deal with a customer of mine who had a new(ish) stiga strimmer, to buy it in exchange for work. The one I'd been using was great (old Kawasaki engine), but ancient and takes so many pulls to get going, I'm knackered before the job begins! Plus bits are needing to be replaced fairly often, which is a pain when I've got work to do.So I used the stiga for a few heavy jobs (long blanketed grass mixed with a few brambles and it seemed strong and starts in 2 pulls every time. After an hour or so, I noticed that the revs sound different under strain. Now it has started to overheat on anything other than very light work. Last time I used it, white smoke was pouring out of the exhaust and I thought it was on fire! I've taken it to my mechanic 3 times, who says that aside from a slightly slipping clutch, he can find nothing wrong. I've checked with the manufacturer and they confirmed the oil ratio is 50:1 (which I make sure is fairly precise and well mixed).Any ideas what could be causing it to overheat? Maybe it's just not not meant for heavier work? I've never had this with my Kawasaki engine.

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Richard Gadsby October 3, 2017 at 9:17pm

What stiga strimmer is it? Is it a strimmer, a brushcutter or a clearing saw size one?
You may have popped a gasket somewhere letting air in messing the fuel air mix?
- Bob beard > Richard Gadsby October 3, 2017 at 9:26pm
  
  Hi, it's a brushcutter (SB44D). I did mention to my mechanic that I thought it was air related. The priming bulb was replaced and now it seems to get lots of air bubbles along with the fuel when I press it. Could the fuel line be doing something?
  
  Maybe I should take it to a new mechanic, but this guy has always been reliable and fair.
Graham Taylor October 3, 2017 at 9:26pm

Providing the cooling fins aren't blocked.... I'm sure the mechanic would have spotted this.............. overheating is probably caused by too weak a mixture. Silly question perhaps ..... are you sure it is overheating? Check the plug...... should be very white to indicate the overheating. Usually a carb problem so the carb really needs taking apart and cleaning. Otherwise, the crankshaft seals might be worn and leaking... a major job to replace. As for the white smoke, if the machine was left on its side/upside-down for some time, on certain models (myStihl fs130 is a good example) fuel will soak into the airfilter/crankcase, saturating it all with oil which could account for the white smoke.
- Bob beard > Graham Taylor October 3, 2017 at 9:44pm
  
  Thanks, yes I'm pretty sure it's overheating. The exhaust area gets far hotter than I think it should. The white smoke only happened once and was about an hour into the job. I'd smelled burning 5 mins before, but thought it was someone burning rubbish, until I looked back and saw it was me! Other times when I've had equipment on its side, the smoking starts immediately on startup.
  
  Today, I took it out for an hours work on an area with very short grass that just needed a tidy. Everything was fine. Then I was asked to cut a path through an area with rotting ferns and a few brambles and it got incredibly hot in just 10 minutes.
  
  I was thinking of giving it a try with a richer mixture. Maybe an extra 5ml per litre and see if that works.
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    Richard Gadsby > Bob beard October 3, 2017 at 9:52pm
    
    I would keep oil level at 50:1 more will only make more smoke!
    Have you checked the carb screws? It might want re tuning on top end and possibly bottom end too. It sounds like too much air in fuel/air mix to me so leaking pipe , gasket or carb problem.
    The carb diaphragms may we’ll have withered if it was not used much
    - Bob beard > Richard Gadsby October 3, 2017 at 10:27pm
      
      I think it was left in a shed for a couple of years, so that's a possibility too! Will ask the mechanic next time I take it in.
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  - Bob beard October 3, 2017 at 10:00pm
    
    Hi John, thanks. That's interesting, because today the overheating happened after I'd refuelled. Trying to think back, I think it has happened at other times too, but when the tank was running low.
    
    How long do you wait to let it cool?
PRO

Andrew Betteridge October 3, 2017 at 9:59pm

More tea?
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    Richard Gadsby October 3, 2017 at 10:39pm
    
    I have to say I’m surprised that a dealer would say that.
    If you are buying pro grade machines that then have to stand and cool it does not add up to me.
    I have strimmers running all day long only stopping at lunchtime and to refuel and never yet had one overheat.
    Mowers running for hours at a time. Same with hedge cutters and to an extent blowers.
    I think maybe if homeowner grade then maybe?
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        Richard Gadsby October 4, 2017 at 10:41am
        
        Your last sentence rings true!!
        I’ve found with hedge cutters more than anything else that if I don’t buy top end models they simply break!
        Blades, plastics, engines gearboxes all seem to break until you start spending circa £500 on short reach and more on long reach.
        As for Efco they have been described to me by a dealer as “farmer grade” so reasonably tough I suppose. I bought a multi tool a few years back and it was rubbish but I think that was aimed at homeowners rather than pro use.