My wife came home complaining that her 98 Sporty (1200 stage 3 SE conversion) was missing again. When she first bought it the coil was shot. Replaced that and it ran great for probably 9000 miles. It was missing when it was cold at idle...intake leak...I replaced the intake gaskets and now its good at idle but when your riding and go to get on the throttle hard it sputters and pops. Me and the local wrench checked the carb out and no blockages, accelarator pump is good and slide diaphram is good. And it is adjusted properly. I thought it seemed to be electrical. The coil ohms out at 2.7 on the primary and 12K on the secondary. Is that a low reading? shouldnt it be around 18K or so? Front plug wire read 4k and rear was 6k. Plugs are not fouled. Just figured Id check with the experts here before I take it to the shop. I hate paying for work that I can do ya know.

 

i dont have an answer for you but i like your tag line, i have that in hebrew tattooed around my neck and throat

 

I had sort of the same problem, it turned out that one of the coil wires was loose and at higher rpms would cause the bike to miss. Good luck.

 

this post at another forum covers all your steps for coil testing.....

http://xlforum.net/vbportal/forums/s...ad.php?t=26608

 

yup already tested the coil and listed the resistance in my first post.

 

A coil can test properly and still fail under actual load conditions.That and if your DVOM isn't high quality the tolerances + or - may let a bad coil appear to be good.Electrical circuits need tested live to get accurate results.If you don't have a lab scope you can't even do it.On secondary ignition parts such as a coil.I'm not going to get into great detail but a marginal battery could cause the problem.

 

slyder, i know you already did coil checks, but in your first post you asked if they were correct or if they should be in the 18k range, which is why i listed the link that had others that had tested and listed the normal resistance ranges for the coil. The coil/ignition system on a sportster is pretty simplistic. Given the fact that it will actually start and run, its just missing i think your looking in the right direction. Given the upgrades you've done to the bike (stage III) conversion, I would not be surprised at all if your coil is going out after 9000 miles, i've seen/heard this before. I'd start cheap w/ plugs. I would Ohm out the plug wires too, not sure if you mentioned that already. Pretty much if the bike will run but not well, you're looking at the possibility of poor fuel, bad coil, bad wires, or bad plugs. If its running and just started missing w/out obvious cause I wouldn't dig deeper than that.

 

You need ring test your coil with an oscilliscope. Testing the resistance will not show a problem that only occurs under a load.

 

yeah its doing the missing under load. All my meters are Flukes. Dont have an oscilliscope. I kinda had a gut feeling it was the coil from day one. Should I stay away from the factory coils? Ive used Accell, Crane and Dyna on other bikes with good luck.

 

did the bike have the Stage III mods when you got it? If so, you said it has a bad coil when you got it, maybe the mod is too much for the factory coil; might be burning it up prematurely. you might be able to check the coil with your multi meter if it has a capacitance setting on it. Most basic meters do not. If you're going to shell out the dinero for a new coil, i'd beef it up to a performance module; it will probably save you money in the long run. Might need to get SE wires n plugs too just for good continuity with a hi-perf coil.