My neighbor had a HRR216 that his son had put weedeater fuel mix in (Dad didn't know this). He tried to get/keep it running for at least 2 hours. Finally brought it over to me and asked for help. I took off the gas cap, you could smell the fuel mix in thr tank. We tipped it over and drained the tank. The spark plug was really fouled out.
Cleaned the plug,changed the oil and put fresh gas/oil in it. When we started it, all the insects within a half mile were killed. Still running to this day

I'd also check the air cleaner. If they didn't change oil, it's unlikely anything else was maintained.

'I'd also check the air cleaner. If they didn't change oil, it's unlikely anything else was maintained.'

All obvious trouble spots were checked. I now believe that thinning of the oil (reducing to 10W base stock) from never changing oil (it was like black ink) is what fouled the plug and probably combustion chamber and valves too. This is one of the potential drawbacks of using multi-vis oil, but all drawbacks are nullified by regular changes. It'll get clean over time with my gas mix. This engine also has the typical early GCV oil leak around the governor shaft at the left rear of the engine - mainly an appearance issue.

Properly mixed weedwacker mix shouldn't foul a plug that badly. I have often run leftover weedeater or snowblower 2-stroke gas in a 4-stroker. It barely even smokes most times. They must have put standard motor oil in it or something.

Saxman, I would be inclined to agree with Bill on the air filter. GC filters do a better job of filtering then most brands. It will intercahnge with the Brigg Quantum Power filter size wise and the brigs will last much longer, but will allow dirt to pass.

The GC filter is a sorta lime green. The very outer rim will remain the original color most times and when the rest of entry side has any discoloration it is time to replace. They will richen up the fuel mix very quickly once going off color and foul the plug. They won't be all packed in with crud, just off color because they stop all dirt from passing.

You can trade engine life while gaining filter and plug time by using the Briggs filter but the Honda filter is no more if not actually less to purchase so I would advise to just replace them more often.

Good thoughts on the filter. It's been replaced now but certainly could have caused a problem in the past. I didn't know they were that sensitive on a GCV.