R80/7 only running on one cylinder

[bluecycle3]

My 78 R80/7 was running as good as ever yesterday when it went down to one cylinder , tried all the usual things like spark, compression,fuel, timing, and cant come up with anything. the bike has a dyna 3 ingition but is otherwise stock.

any help appreciated thanks greg

[James.A]

If your bike has fuel, spark, compression, and timing there is no way it won't run. Concentrate on the cylinder that is less hot of the 2 after a minutes running time. There are a lot of things you don't say about the bike, but if you have been running for all season thus far and had an abrupt and complete loss of power from one side I'd look at the spark. Try this; pull both spark plugs and then put the cables on and lay them against the cylinders. Then close the garage door and put out all the lights and hit the starter. Both plugs ought to throw a hot blue spark at the gap. If only one is sparking, or if one is weak and spindly, switch them to the opposite sides. That way you can tell if it is the plug or something that is specific to the cold side like a plug wire or coil not firing.

In the case of a more gradual onset of trouble. I would look at the valve adjustment, since that could be side specific.

If you are satisfied that the first 2 are in good order, then you have to consider fuel delivery.

Check the Airheads web page for lots of good information, and good luck.

[donkey doctor]

Hello; I had that problem recently; it was rust from the inside of the tank was plugging up the fuel filtr on one side. I flushed out the filters in the taps and the ones in the filters, then I took off the float bowls and flushed them out, and blew out the float needle and seat. The rust had blocked the pipes that go into the tank at the taps, and I had to blow them out too. I also changed fuel lines at this time, I was putting new fuel lines in my VW so I had all this line around anyway.