Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board Fuel in cylinder head?

Parked my 67 Lightning after a short ride but unfortunately left the petcocks open over night. Came out the next morning and noticed a stain of fuel under the right side under the engine. Checked the spark plugs and noticed the right one was wet. Local mechanic said I probably had fuel in the cylinder head. He advised to kick it over several times with the spark plugs removed to dry out the cylinder head. I did this but am unable to start the bike. Also changed the engine oil. Is this the right solution? Do I need to give it more time to dry out? It concerns me that there was a fuel stain on the floor. Where did it come from? Didn't notice any drip marks on the engine or frame where the fuel dripped down.

Did you remove the sump plate when you changed the oil?

maybe try new plugs. ya done right so far. I wouldn't worry about the stain on the floor. you may

The bowl vent on an AMAL is one of the holes at the back near the air filter
When the float valves fail to stop the flow of fuel it rises till it gets to the vent hole then proceeds to fill the air filter with fuel
Thus when you try to start the bike the air passing into the engine will be saturated with fuel befor the venturri add even more
SO it will be over rich , most likely on the left side as that carb is lower than the right if left on the side stand
IN theory the entire air filter could fill with fuel and then it would run down the carb throat & pour into the cylinder but that would be fairly rare and require a ver restrictive element in the air filter .
So take the filters off and see if they smell of fuel.
If so discard them even after the fuel evaporates the paper will be compromised .

I have had a number of bikes fill the crankcase with gas because the petcocks were either left on or leaked internally. Worst was on my Norton Atlas. Inadvertently left the petcocks on all winter. Filled up crank case and leaked from there through the main bearing into the primary where the ethanol in the gas dissolved the epoxy coating on the stator and turned it into a nasty mush.

Ed from NJ

ok off topic a bit but:

decades ago was driving across Nullabor Plains ( real long road of nothing in Oz , around 3000 miles) noticed car was using way to much gas,,, oh well , filled it at a road house ( which are located about a full tanks drive apart) and continued. It got worse. Diaphragm in manual gas pump had ruptured and gas was going straight into the sump... so oil would have been SAE 3 .... absolutely stuffed the engine but just managed to limp into Perth .

Moral of the story gas in the oil will take out the motor .

htown70, I'm fairly new to all this. Not aware of a sump plate on my bike. Looked in my parts manual couldn't find anything by that name/title. Is there another name for it?

BSM_WM20, Thanks for the explanation. Makes perfect sense. Will replace the air filter elements.

part #67-1285, it's called a cover in the parts book, you will probably also need the gasket. part #67-1288. Remove the plate and clean the screen. If you have gas in the cylinder it may have leaked past the rings and collected in the bottom of the engine.

The plate is located at the very bottom of the engine. Empty all oil out and replace. If you have a screen in the sump, you will need 2 gaskets. Left carb may be fine if needle at float works properly.

htown70 and Roadwarrior, thanks for the info. Changed engine oil again. This time dropped the plate and replaced gasket with two new ones. Though the price of oil has gone way up, it is still cheaper than an engine rebuild.