Motorcycle Repair: Bike dies with throttle, 1986 honda nighthawk, honda nighthawk 550

Question
Hey, so I bought a 1986 honda nighthawk 550 (my first bike) and fixed it up a bit. By that i mean my neighbor and i cleaned the carbs, replaced the throttle cable, and fixed the the clutch and brake cylinders. It was running fine for a few weeks, then I wasnt able to do anything to it for a little over a month because I got too busy with work and whatnot.

Anyways, since i fixed it up, it had trouble running when first started up, but if i let it warm up then it would be ok and have no problems.

I tried starting it today, and it had a problem starting (just like normal) but it didnt seem to subside. I had to let it warm up for a little longer than other times and still when I applied the throttle it would die. Finally got to do a couple of laps in my couldesac and then sat for a second to talk to a buddy, and the problem not only persisted as before, but now was worse. It would now die even with the choke on and not applying throttle....and now I cant get it to start at all. Im curious as to what it could be...thank you.

Answer
Hi Joel,

One problem that happens on older bikes
is the fuel system gets gummed up or the tank
is a bit rusty inside.

I would check if your fuel flow from the tank is
okay and then add small inline fuel filters
available from motorcycle or auto stores.

Next you will have to see if the carbs are filling
with fuel and if necessary you may have to
try to blow out the carb jets again
or try filling the bowls with some good
yamaha brand carb cleaner and let them
soak awhile. The yamaha cleaner is safe for
rubber parts.

Make sure your gas cap vent is open to allow air
into the tank so the fuel can flow properly.

Once you get the fuel system checked out
also make sure the battery is good and charged fully.

Low battery voltage can cause the ignition to cut out
but hesitation is more likely fuel starvation.

The petcock fuel valve on the tank may be
a vacuum type, if so it requires engine vacuum to
open it. Sometimes the rubber valves will fail
and then no fuel will flow to the carbs.

Fuel can gum up carbs quickly so use some
fuel stabilizer if you plan to have the bike parked
awhile.

I think if you get the fuel system clean and check the battery
that should help.

The fuel filters will save you alot of problems in the long run.

Luck!

Wayne S
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