Honda brush cutter runs out of power

[Franny K]

I bought this 35cc honda brush cutter/string trimmer (bike handles) last year late summer or early fall. I have another one I got a few years earlier that works fine. This one idles fine all the time but after two to 20 minutes it looses top end and will stall if too much throttle. Last year I could use it by closing down the choke most of the way. This year it worked properly the first time maybe 20 minutes but now it is up to it's old tricks.

I can have it running essentially idle only, drain the gas, either run it dry or prime it dry, re fill and it works normally for a while. I have taken the carb apart to look for debris and made sure the fuel line was not kinked. What I think is the main jet is smaller than any drills I have #80 or close to that. It is still under warranty but not sure they would actually fix it. A new carb is quite cheap perhaps I should try that then I could drill out a jet, there is a local guy that seems to drill out jets with good results. Non adjustable carb. I was going to get a plug when I took the picture but it was too late, might switch the plug from the one that works well.

I think I checked the valve clearance last year some things can misbehave it too tight.

Any one know of similar behavior or remedy?

Thanks

 

[triptester]

There should be some sort of vent on the fuel tank which might be plugged. When it acts up open the fuel cap to see if it sucks air and runs better.

 

[CacaoBoy]

It is still under warranty but not sure they would actually fix it.

Well, if it is under warranty and not running correctly, I would take it to the dealer. If the dealer can't/won't get it running correctly at no cost to you, or if you just do not want to deal with the dealer, then look for self-help solutions.

For what you describe, I'd try some Seafoam in the gas. There are people who say it is worthless, or worse, and there are people who claim it it is a miracle cure. I am somewhere between those extremes, but have found that it often seems to help when there is a fuel related problem, and I use some periodically in my Honda HHT35SUKA trimmer (yours looks to be the same model) when it has a loss of power such as you describe. The carburator seems highly vulnerable to minor fuel imperfections and can collect varnish even when run dry. Use ethanol-free gas if you are not already doing so.

 

[Franny K]

I got a new plug and loosened the intake valve clearance a bit. It did not respond to dumping out the gas and running it dry like it did yesterday. The tank vent must be in the cap but actually running correctly has been only after sitting all winter and described above. I am back to exactly the same mark to put the choke at as last year. Cracking the cap makes no difference.

Perhaps they put the carburetor for the 25cc model on it? There is a small channel going from the intake port to the impulse opening on the carb and a gasket. It is really small like half a small worm hole. At best half a lead (graphite) of a normal pencil.

As to the fuel. I generally use no ethanol gasoline in the small equipment like this. I hoped that would work last year. The carb is clean inside. My eyes can't see well enough to tell if the jet is blocked. They have usb microscopes now that are pretty impressive but I don't have one. I got it at a huge John Deere dealership in Marietta Ohio. They said just put it in a shopping cart and wheel it over to the service window. I am over the river in WV it still is usually a good part of a day when I go to Marietta and then I may be far away if and when they decide it is fixed.

I bought the first one at the Honda motorcycle shop in Marietta. They did not have any when I wanted the second one. I even prior got an Efco powered device with this engine. I got that from Baileys when the dropped Efco. It had a valve keeper come off when I started it up and revved it the first time. It ran sort of for a while and eventually I had to put a new valve in it and it never had this issue.

 

[Franny K]

I switched the carburetors on the two of them and the problem follows the carb bearing numbers 36 522 and the earlier one that works well is stamped 36 336. I bought a carb off ebay for about $10, even has a spare sponge like air filter that seems to work properly but has no numbers on it.

Still a mystery why the problematic one worked as it should after sitting all winter and as described and posted at the start here.