Discussion in 'Engine, Fuel and Exhaust' started by stjohjo, May 18, 2009.
how is the best & cheapest way to unstick '77 sporty bottom-end(fuel was left on)?
Welcome Stjohjo to HDTalking, and hope we can help you out. If fuel got past the carb needle, the whole oil sump (pan) and possibly the cylinders are full of fuel also, and depending how long, gasoline is a solvent in the beginning so it can work it's way past oil seals and flush the grease out of any bearings as well. If allowed to sit, gasoline volatile vapors evaporate leaving an oily residue, and if allowed to sit will turn to a sticky varnish (it smells terrible, like old paint).
Drain the tank completely, pull the fuel petcock and inlet filter and replace if the fuel petcock shutoff valve was defective and cause the problem in the first place. Do not put any more fuel than cup or to of fresh fuel to clean inside of loose particles (drain in clear jar) and repeat till clear. Cleaned up the carburator and fuel tank and fueling system should be all clean inside. You will need only a 1/2 gallon of fresh fuel to warm the bike and do the oil change to follow.
If the bottom end is full of old gas/oil (called "wet sumping") this excess oil has to be removed. Check your manual to see if the pan needs to be pulled to drain any standing fuel (it may have a drain plug) to do this easily. Pull the spark plugs to eliminate possible hydralic seizure damage in case the cylinders are flooded (liquids are not compressable). Might want to put a teaspoon of motor oil or spray some WD40 into the plug holes to thin and clean the gunk inside the cylinders. You should be able to crank the engine to spread the cleaning lube, check that bottom is not "seized" and engine spins freely with no compression. If it does this fine, put the plugs back in.
Finally, do a complete oil change with filter. You can use a cheaper "FRAM" or aftermarket one as this is only going to be tossed along with the flushing oil. If possible pour a small 1/4 bottle of Sea Foam, Berryman's Chemtool or Marvel Mystery Oil to help flush out the old oil/gas in the crankcase, then you refill to the proper level with regular petroleum based oil, as you will probably like to run it for a couple 20-30 miles and change them both again with your more "permanent" or preferred oils and gear oils you ultimately like to use. Good luck and hope this helps.
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