Sportster firing on one only!!
#11
03-04-2009, 06:31 PM
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#12
03-04-2009, 06:42 PM
Like others have suggested, start simple and go from there. Pull the plug check the gap and if fouled, wet or what ever. I had that problem with my 1996 Buell S2T. It was always the plug and always just the rear cylinder. It would still go 50MPH on just one cylinder...don't ask me how I know........ I often wonder if it was a fixable mechanical flaw and why was it always the rear cylinder? I changed out the plug wires and always started keeping a fresh set of plugs and gapping tool in my bags.
I had that happen way back in 1981 on my Low Rider. Rode from home home to my apartment in OKC (stationed at Tinker AFB) and could not understand what was going on. 50mph tops. Oh, and had to have help from troopers twice in that 100 miles because I kept running out of gasoline. Pulled it into an indy shop once down there and he listened to it for a second and said, "you's gots a fouled plug on the rear cylinder".
Sure enough, new plug and she ran like new again. Still don't know how he could tell just from listening. Sounded fine to me.
#13
03-05-2009, 10:31 AM
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#14
03-05-2009, 10:53 AM
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#15
03-05-2009, 11:22 AM
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same thing happened to mine
turned out to be.....
rear cylinder intake plenum gasket...
simple test....start the bike,take a can of starting fluid..spray around the rear cylinder at the intake plenum
if it picks up rev's...you got yerself a leak..
PITA to fix...but only cost about $12.00
go ahead and relace both gaskets while your there..
IF that's what it is..
turned out to be.....
rear cylinder intake plenum gasket...
simple test....start the bike,take a can of starting fluid..spray around the rear cylinder at the intake plenum
if it picks up rev's...you got yerself a leak..
PITA to fix...but only cost about $12.00
go ahead and relace both gaskets while your there..
IF that's what it is..
#16
03-05-2009, 12:08 PM
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#17
03-25-2009, 01:53 AM
I've had one cylinder problems before and it turned out to be carb adjustments. I tried everything from new spark plugs to wires to coil to intake manifold gaskets and still had the same problem.
What seemed to work on a couple different bikes was cleaning the carb out real good dropping the bowl cleaning it out and setting the float, next adjusting the idle and mixture to the standard setting as recommended by whatever carb it was. Had it happen on stock harley carbs and s&s carbs.
What seemed to work on a couple different bikes was cleaning the carb out real good dropping the bowl cleaning it out and setting the float, next adjusting the idle and mixture to the standard setting as recommended by whatever carb it was. Had it happen on stock harley carbs and s&s carbs.
#18
03-25-2009, 08:58 AM
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#19
03-25-2009, 09:40 AM
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#20
04-01-2009, 07:56 PM
Yeah a month shouldn't cause the damage you're describing. The first thing to gum up would be your carb and since the front is firing, we know you at least are getting fuel there.
I'd say check compression first, just not acurately. You can do it without a gauge pretty easy, just put it on a lift, pull both plugs, put it in gear, put your thumb over the plug hole in the back jug and spin the wheel through a cycle. If you feel the air pushing your thumb off the hole or pulling your thumb in, that should be enough to fire.
Also, pull both plugs and turn the bike over. In a few rotations you should see fuel start dribbling out of the plug hole. That can at least verify that fuel is getting to the back jug, but since it's a carb bike that should be happening if the front is so the odds are low that fuel delivery is the source of the problem.
I'd say check compression first, just not acurately. You can do it without a gauge pretty easy, just put it on a lift, pull both plugs, put it in gear, put your thumb over the plug hole in the back jug and spin the wheel through a cycle. If you feel the air pushing your thumb off the hole or pulling your thumb in, that should be enough to fire.
Also, pull both plugs and turn the bike over. In a few rotations you should see fuel start dribbling out of the plug hole. That can at least verify that fuel is getting to the back jug, but since it's a carb bike that should be happening if the front is so the odds are low that fuel delivery is the source of the problem.
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