do not fool with the unit or it will void the warranty

Great help mowerman, lol.

I'm not sure what kind of air filter it is but it does sound like an air/fuel mixture problem.

Simple way to check if it is not getting enough air is to try throttling it without the air filter on. Of course only do that in a "clean" environment to avoid sucking things into the engine.

If not that, maybe a carb adjustment, but that does not seem the likely culprit.

After that it would be beyond me, but maybe some sort of crankcase leak.

There are others much better than me at diagnosing engine problems. Probably the 14 year old kid around the corner or his little sister, lol.

So what is your recommendation on that Honda trimmer?

Hi,

I have a Honda HHT31S trimmer. 3 Years now and very reliable. My guess, and it is only a guess is that maybe one of the throttle setting screws on the carb cable has got a little loose. Check page 28 of the manual. Try tweeking that. Maybe when you gas it, you are pushing the air valve a little too far. Hence too much air, not enough fuel hence works great at idle and not so great when you pull that throttle cable.

As a quick check, try pulling the throttle halfway OK there? then like 90% of the way, OK there? If it is, seems like a minor tweak to the throttle cable adjustment nut might do the trick.

The other issue, less likely is OLD petrol. I always use a fuel stabilizer addative like STABIL, available at Home Depot. Red in color, looks like cough medicine. It could be that if you have not use your trimmer in a while, the fuel gummed up some of the carberuttor jets.

Best, Mike.

Thanks guys for the help.

I posed in another site also. This and together with the feedback from the other site confirm my suspicion, the problem is most likely in the carb. It is under warrante, I just took it to the dealer already.
THanks

Did you ever figure out the problem? I have an HHT31s that is doing the exact same thing...I've been working on it and found nothing obvious. Thanks in advance..Jason

Wow: Yung and Mas ! What happened ! Low & High Speed Jet Restrictions all the Way Baby !

Stinky: You were the closest as to Main Jet and Secondary Fuel Circuit Fouling ... Don't Yeah Love it ! We have all Been There :)