Cleaned the carb, solved that issue. No more fuel overflow, starts and idles like mixture is regular.

Judging by the way it was starting, my blackish spark plugs, and the fact that my float needle was not seating I am 99% sure some gasoline ended up in the cylinders, which I understand to be a problem. How can one tell if there is gas in the oil? Does the oil have a sheen? Does the gas seperate? Also, what is it about gas that causes such a problem in the crank case? Is it the prospect of it igniting, or does it change the lubrication properties of the oil?

When I change the oil, is it so bad that I should change it cold or should I give it a quick ride to heat it up like a regular oil change?

EDIT: Speaking of spark plugs, would I need the same spec plug since my carb is an "upgrade" (Mikuni VM38)?

 

The choice of spark plugs is determined by the ignition: for my 1978 i use NGK BPR6HS with electronic ignition, the NGK equivanent to the factory recommendation [which i forget] when i had points.

On these bikes with an oil tank i think it is unimportant to warm up the oil before doing an oil change. Hot or cold it will all drain out of the oil tank. i would run the engine just long enough to ensure that it has not wet-sumped, less than a minute to see if oil spews out the crankcase vent.

The problem with gas in the oil is that it wrecks the lubrication. The rings will srcatch up the cylinder walls, the cylinder will overheat, pistons may bang around, whatever. Others know better about this than i.

I have not [yet!] had a gas-in-the-oil problem, but i have heard that you can smell it.

I would just change it. However i understand that $s can be an issue. Oil and filters are not cheap like in the old days and you may not want to change it if it is not necesary. See if you can smell gas in the oil tank, and wait for someone else to advise.

 

i do run mine up before changing the oil, also to make sure the oil is all in the tank but also if its cooler out side it takes forever to get the straight 60 to drain!!, good that the carb is fixed for now but u have had repeated problems with the same thing, really need to look into whats getin into your carb

 

Thanks for the help guys. I am going to look into an inline filter that will fit my tiny length of fuel line.

As far as spark plugs go, I have been blindly ordering the NGK plugs that J&P said would be for my bike, but it turns out looking at a cross reference sheet these plugs are not the right type. Service manual calls for Harley #5 plugs, the cross reference I found on the XLforums was 4R5, is that an updated version of the #5? I have a points based ignition. I am going to get some oil and plugs today, should I just ask for a Harley #5 at the parts counter, or does the XL forum reflect newer than 1978 technology, meaning I should get the 4R5?

I am also convinced that the knocking I mentioned is piston slap, judging by what I have read on the internet over the past week.

 

Check out auto zone for plugs. They had in stock the plug when I was running points. Now with elec. ign I run the same NGK plug as Mick but they never have in stock always have to order.

 

i run hd 3-4---sometimes hd 4---only run hd 5 in summer at the strip--5 is a cold plug