Haven't done it, but came close once in the car when I was in ND. Freaked me out... Glad I caught it in time. Yea, as I recall, the nozzle wouldn't fit in the tank, and that's what stopped me... Whew!! Close call.. Too bad about your buddy... (It was your Buddy wasn't it?)

 

As a lieutenant back in the day I stood with my platoon sergeant and watched the battalion XO's driver fill up his quarter ton with diesel. His driver had tried to warn him but the XO just chewed him out and told him to top off from "that" tanker. Good fun for all!

 

I haven’t my self but I did see a lady at the pump next to me try it. I was pumping gas in my truck when I here the person at the next pump cursing and having a fit because the “stupid dumbass nozzle won’t fit” in her Rav-4. So I asked if she needed some help and she said the nozzle wouldn’t fit in her car for some reason. “It’s a good thing it doesn’t fit, you don’t have a diesel car lady” “Oh!! they should do something to let people know it’s a diesel pump” “They do, it says so on the pump!”.

 

Okay, I admit I topped off the tank with 1 gal. of diesel by mistake (black handle). Bike ran like crap, but ran. Tons of white smoke. My buddy just about wet his pants when I finally fessed up. We initially thought bad gas, or water in the gas.

Funny thing is, I have a '99 carbed RK, and after running the diesel mix through the engine it must have really cleaned out the carb because it has run fantistic ever since.

Okay, flame away.

 

Did he put in premium diesel or just regular unleaded?

 

The problem with diesel is that it burns too well which can damage an engine quickly. Pre-ignition is hard on an engine and many have experienced it say when forced to use 85-86 regular in the summer. Diesel is something like 47 octane!
Your friend was very fortunate.

 

Harley should take a cue from Dodge (dodge manual says premium is not good for the truck and shouldn't be used) and build the motors that allow there bikes to use regular at the pumps. Listing for premium is BS (I imagine its the EPA compromise). Can't they get the compression ratio down say to 7.5:1 or whatever the cut off is for being able to use regular gas and still make EPA happy?

 

Yes you have to be careful at some Stations when filling up, look closely at the Pump Handles, Gas has 3 selections for Grade of Gas and Diesel has 1, not all handles are GREEN, I have to remember this when I am on the Bike also because My Truck is Diesel.

Diesel does not have a Octane Number, it is Rated by a Cetane Number.

 

That shouldn't be a problem if you would be happy with less power. But they're only putting out 65-75 HP as it is. It's not about emissions, rather about power. I think the old Pan Heads had a lower compression but probably only 50 HP.

 

I always put premium in the bikes so I am looking for the button or nozzle that says 93 Octane. Don't think the deisel pump has that