Gummed up Carburetors

[Mrwurm]

I seem to have the worst luck when dealing with carbureters on certain types of small engines. They seem to gum-up and clog after a short time of non-use. (I use StaBil fuel stabilizer in all my machines) I have the most trouble with the following three machines:

2001 Honda XR70 4stroke
2003 Suzuki DR125L 4stroke
1991 Honda FourTrax TRX250X 4stroke

We only ride these bikes about twice a month during the summer and that is not often enough to prevent the fuel systems from clogging. The FourTrax must be started every day to keep it viable. If It sits for three or more days it requires starting fluid and 50 to 100 kicks to get it going again. The XR70 is the worst. If it sits for a month, the only thing that will get it going again is a carb removal, disassembly, and cleaning with gumout.

In contrast, the following machines can sit all winter with fuel stabilizer and start right up in the spring:

Honda Mower 4stroke
Gravely Mower 4stroke
Homelite Blower 2stroke
Weedeater 2stroke
Edger 4stroke
Tiller 4stroke
GoCart 4stroke
Snow Blower 4stroke (sits all summer)
Generator 4stroke
Power Washer 4stroke

The above listed machines have no trouble sitting idle for long periods and fire right up when needed. What is it about the the three machines I have trouble with?

 

[bgott]

I have no experience with the three engines you have problems with but, I noticed that the ones you don't have problems with are all simple machines. The Japanese have always had the " If you can't dazzle 'em, baffle 'em" syndrome so I imagine the carburators on the three you're having problems with come complete with lots of tiny passages and circuits that plug up with hardly any excuse whatsoever. There isn't enough money in the simple machines for them to get cute with the design. Or maybe magazine reviewers don't rave over sophisticated cutting edge designs in lawnmower carburators yet. You might even try skipping the fuel stabilizer in these three just to see what happens. It sounds like that Fourtrax might have operating or tuning problems unrelated to the fuel age or quality. It should take more than a day for it to go stupid on you, as I'm sure you already know. Have you tried changing the plug a couple of times? I say a couple of times because new plugs have been known to be bad right out of the box. Good luck!

 

[Rch]

M, A manuever that has worked for me is let the fuel get low, add some lacquer thinner ( same as Gumout) to the tank as it is running so it runs a little ragged and need goosing to keep it going. Do this for 7-8 minutes. Then add enough fuel to the tank so it smooths out and go for a ride for 20 minutes. I would consider shutting the fuel off, run it till it quits. Store it a month or 2 and top off the tank with fresh fuel before trying to start it again. I assume fuel filters, dry gas and any crud in the tank have been addressed.