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I have a 98 Sportster 1200c. I’m not sure which category to post this on as I’m not sure if it’s a fuel or fire problem. I was stranded 15 minutes into a ride and couldn’t get it restarted til it cooled down. I ended up replacing the ignition coil, which solved my problem. In addition, I replaced the plugs, and wires and the air filter. It ran great for about 250-300 miles, then mid ride, it started missing and bogging down about half throttle and higher. It backfires a lot, then catches and revs for a few moments, then misses and backfires and bogs down again. Since the problem, I double checked the connections connecting power to the coil and inspected wires. Then same from the coil to the plugs. I drained the gas, replaced the fuel valve filter/screen in the tank. Replaced the plugs again (one looked a little cooked) did an oil and oil filter change. Used a fuel additive (octane booster) with the new fresh tank of gas and still my problem persists. Please help me diagnose this. I can’t keep dumping money on “maybe this is it!” Sorry this is so long, thanks for your time.
 

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Has the tachometer been removed? Sounds like a stupid question but, I had a 1980 fx that the prior owner had removed the tach. He just cut the lead wire w/o capping or removing it. That bike was a PIA to troubleshoot and i made the mistake of "keep throwing $ at it". That doesn't work! I learned the expensive way (even rebuilt the engine) and it didn't help.

My advice is to troubleshoot one path at a time:
1 AIR, Check for vacuum leaks by spraying wd-40 around the intake manifold while its idling. (Don't let the spray into the velocity side of the carb. It will skew the results.) If the RPM climbs as the WD is misted behind the intake, its a intake leak. Either a cracked hose or a intake seal. I had one with the rubber intake manifold was cracked.

2 Fuel: Clean the carb and replace the fuel filter and or screen. Check the fuel line for cracks.

3 Electrical: Clean the grounded area where the coil mounts. Check all grounded contacts for clean/ rust free contact and torque.

One other point:
That column that serves as a bar riser / gauge mount on the Sporty "C's" Is a wire birds nest! If you have been inside that for any reason prior to this problem with the bike: Go back in there first!


Examine it very closely for pinched cut / scraped wires and check that the solder joints are not cold (grey scale) or cracked. That column is a PIA to get closed up with out effin' something up in there! Ask me how i know this!

Keep us in formed of your progress and Best of Luck with it!
 

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Check everything the other guys have to you to do.

But to me it sounds like the Electronic Ignition Module for that bike. That Module for your model resides on the Engines Right side if your sitting on the Bike, it's in the Cam Cover. It's probably Fried at that age. If you have to Change it I would check with S&S Cycle, I use the HI-4N Cam nose Cone Module with a Single Fire Coil. It's great. After this is done you will need to have the Timing set again.

To gain access to that area to remove the Electronic Ignition Module you will have to drill out the Rivets on the Cam Chest Cover using a drill the size of the rivet, so this Cover will come off, just be carful with the Cover. Once you've removed the cover you will see another plate with 2 small screws. Take that inside Plate off and becarefull with the Screws Heads because they are Stuck. Once it's off look at the Covers Alignment rivet holes and the inside Plate Screw holes to see if they line up if so go to the Hardware store and buy Screws long enough to remount them both together.

Now if they don't match you can still drill and tap holes on the Inside Plate for the Cover Plate to be attached to using small screws rather than the Rivets again and I mean Small Screws, You Don't want the screws boring holes inside the Electronic Ignition Module. Doing this proscess makes it so much easier in the Future to access.

If you want to know all about your Machine and how the Parts all fit together then go to this Harley website and Register as a Independent Operators

Just follow the Prompts and instructions.

 

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I have a 98 Sportster 1200c. I’m not sure which category to post this on as I’m not sure if it’s a fuel or fire problem. I was stranded 15 minutes into a ride and couldn’t get it restarted til it cooled down. I ended up replacing the ignition coil, which solved my problem. In addition, I replaced the plugs, and wires and the air filter. It ran great for about 250-300 miles, then mid ride, it started missing and bogging down about half throttle and higher. It backfires a lot, then catches and revs for a few moments, then misses and backfires and bogs down again. Since the problem, I double checked the connections connecting power to the coil and inspected wires. Then same from the coil to the plugs. I drained the gas, replaced the fuel valve filter/screen in the tank. Replaced the plugs again (one looked a little cooked) did an oil and oil filter change. Used a fuel additive (octane booster) with the new fresh tank of gas and still my problem persists. Please help me diagnose this. I can’t keep dumping money on “maybe this is it!” Sorry this is so long, thanks for your time.
Hi, Check you ignition connection on the motor and and see what is fitting eg: Dyna, Twin Tech or any other model because I had a similar issue on My 98 xl when it got hot it started to brake down I had to change my ignition modal to fix the issue.
 

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Double on the ignition module located behind the 'points cover'. Pop the cover off and see if the module looks melted, time to replace that.
 
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