I'm working on a Husqvarna 128DJX for my dad that's smoking while under load. At idle, there is no visible smoke. At half throttle, you see white smoke, and at full throttle, you really see it. On top of that, there's what looks like black oil all over trimmer on the left side where the exhaust is.

I have changed the spark plug, replaced the air filter, cleaned the spark arrestor, dumped the fuel and put in fresh, and replaced the carburetor. I took everything apart and visually inspected the outside of the motor where the head gasket is, but did not see any leaks nor hear any air escaping.

The oil to gas ratio on this model is 50:1 and he's been buying the pre-mixed cans that are ethanol free for years.

I am out of ideas; what could be causing the white smoke and oil-like deposits on the trimmer?

EDIT: Link to parts diagram

  • 1
    Welcome to Motor Vehicle Maintenance & Repair! Did you check the intake reed (I'm assuming it has one) which controls the backflow of intake charge from the carburetor? It should be on the side of the cylinder where the carburetor attaches to it. It sounds like your mixture may be too rich or isn't doing a complete burn. This is about the only thing I can think of considering you replaced all the other parts. I would have suggested your gas mixture might be at fault, but you cannot go wrong with premix for 2-stroke engines. Jul 24, 2018 at 17:03
  • I don't know if it has one, I'll have to look when I get home tonight. I don't remember seeing one...would it be more inside the engine itself?
    – Carl
    Jul 24, 2018 at 19:57
  • Yes, like I said, it should be on the cylinder wall. The reed valve is used on most 2-cycle (or 2-stroke) engines in place of valves. Piston shape provides the rest of the sealing needed so the engine can run. Jul 24, 2018 at 20:13
  • Thanks for clarifying. I looked at the parts diagram and don't see any mention of a reed value. I've updated the OP with a link to the parts diagram, in case I missed anything.
    – Carl
    Jul 24, 2018 at 22:21

2 Answers 2


all I would suggest is verifying the premixed is 50:1 for trimmers. 2-stroke mopeds etc take different mixtures and he may have gotten the wrong can. White smoke implies it has too much oil in it. When you replaced the gas, did you try replacing it with gas from a different can, or did you refill it from the same one?

  • Different can...he runs the premix, I had a container that I had mixed for myself, same result.
    – Carl
    Jul 24, 2018 at 19:58
  • then it may have something wrong with the ring (if it has one) or a scratched piston or wall.
    – John Lord
    Jul 26, 2018 at 5:16

The oil near the exhaust seems to indicated that you have unburned fuel (which includes oil) in your exhaust, and that would point to a rich fuel mixture.

I have a Husqvarna trimmer (not sure of the model) and I know there is some degree to which you can adjust the carb tuning because I've had to do it before. I would take a look online and see if you can find a tuning guide for your model.

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