non oxy Gasoline?

[DRH1175]

I have been running nothing but this for several years in all of my small engines and off road engines. John Deere tractor, Honda Foreman, Ice auger, chainsaws, weed whip and generator. I have had no fuel related issues since doing so. My question is this. Last fall when I serviced my Yammaha Generator when looking down the spark plug hole I noticed some carbon build up on cylinder head and walls. I have only 60 hours total on the generator. Now yesterday I noticed quite a bit of carbon on outside of my Foremans muffler. Would this be because of the fuel or because of warming up with choke on? If fuel should I add a additive, or switch brands? I have been running nothing but Tesoro. Thanks!

[Eric Wettschreck]

Carbon or soot comes from a fuel rich mixture. When you pulled your spark plug out what did it look like?

My guess is it's either running too long choked or the plug isn't burning hot enough.

[DRH1175]

The spark plug was actually clean. maybe what I saw was normal. I just thought the cylinder walls would be shiny clean after 60 hrs. On my ATV could extended warm up times with full choke cause the buildup on outside of tail pipe. I have used my atv for ice fishing a lot this year compared to years past.