Honda GX390

[KE4AVB]

Well I got one that not really making much since to me. It is fouling out spark plugs. Actually they are carbon shorting. BPR6ES plugs so I trying a BPR4ES hotter. Doesn't seem to be running rich just shorting out plugs.

Any thoughts?

[bgsengine]

I'd probably take an otoscope to the plug and see what sort of carbon fouling it is - try and see if it is loose carbon from inside the combustion chamber, or if it is maybe a fuel related (or even a misfire related) , or oil fouling, or does the engine run in an environment with metal or ceramic dust, etc. That might offer clues as to what is causing premature fouling.

[KE4AVB]

Well since just got it a coil set for the 390 I will install it and I will also do a carb tear down to see if there is any obvious problems.

This is used on an UTV so not going to be able do much actual testing. The customer is going to need to do the field testing for me. just hope I can find the problem. Just don't like guess work.

[bgsengine]

Yeah, I'm just saying, a close inspection of the carbon bits inside of the spark plug may give you some clues (or get one of those USB microscopes for cheap for an even closer look?) rather than testing for anything, it is more of observation for possible clues (Wonder does the UTV operate around natural gas fields or some such? Things that may contaminate the air and get through typical air filters but don't burn off completely in combustion..) That's what I mean just considering the environment it runs in for external clues.. all other things being equal, might the same thing occur to a different engine that operates in the same environment, etc? - Or, even better - does the UTV only run for short periods, which may mean it never gets to full stable operating temperature so as to burn off carbon?

[KE4AVB]

Kinda thinking it might be the low usuage being a factor which is why I up the plug tip temps. I had a good look at the plug and it is just carbon fouling like it is burning way to rich. Gravity fed setup so no pump to over load the needle valve.

I do know some else had worked on it so no telling what was done by some of the idiots around here. I even seen a carb that someone tried using RTV to replace a o-ring gasket. It didn't work and fill the carb when all kinda pieces of RTV.

[KE4AVB]

Well finally work to the Chuck Wagon. It did turn out to be carburetor problem cause by whoever worked on it last time. Idle mixture extremely rich. Adjustment screw was out about 5 turns. And the pilot jet o-rings screwed so that was adding to extra rich mixture too.