running on one cylinder

why would a harley run on both cylinders at half throttle+ but not at tick over?runs on the front cylinder only...
oh its a 1971 xlh

[Limey_Dave]

I don't "know" your model but in general terms it sounds like ignition fault.
If it's banging away on one pot at tickover it's not likely to be carb,if a jet was blocked or float sticking it would stop.
Unless something odd has happened to the points to stop the right gap on both cams,I'd say it's high tension side.
If it's wasted spark coil,swap the leads at the coil end.If it then runs on just the back pot then it's coil.
If it still runs on just the front then it's prob lead breaking down.
How did you decide the coil was ok?

[chilly]

and don't forget to check the plugs,easy stuff first

Originally Posted by Limey_Dave

I don't "know" your model but in general terms it sounds like ignition fault.
If it's banging away on one pot at tickover it's not likely to be carb,if a jet was blocked or float sticking it would stop.
Unless something odd has happened to the points to stop the right gap on both cams,I'd say it's high tension side.
If it's wasted spark coil,swap the leads at the coil end.If it then runs on just the back pot then it's coil.
If it still runs on just the front then it's prob lead breaking down.
How did you decide the coil was ok?

we got a spark
been told it could be something more...serious

[panheadpete]

Wot Limey_Dave and chilly say; also, if you haven't got new plugs to try, swop front for rear and see if the problem goes along. Next, compression tests - if you don't have a tester, just use your thumb, that will show any obvious difference. Just a few possibilities.
Cheers, Pete.

[kevscrivener]

Don't discount the carb; it may be suffering fuel starvation.

Sporties "catch" on the rear pot when you start them so that should be firing OK otherwise you'd struggle to start it at all. Are you starting it on button or kicker?

I would, as Chilly says, swap the plugs over (first simply change cylinders over, if no different fit a new set of plugs) as a starting point; give the carb a good blast of spray cleaner once you get it running, just in case you've got a bit of crud in it.


Out of interest, I had a similar prob with my 66 XLCH which turned out to be a partially blocked choke tube in the Bendix carb.

start in the starter,i value my knees