Venting, Charging System, Ignition

Q: Dear Fix My Hog,
I always read your e-mails! I have your Fix MY Hog DVDs for my cruiser. I also own the manual by Haynes Service & Repair for the Sportster
1970-2008 models.

I have a 2002, HD 1200 Sportster, Custom

The problem : On longer rides (> 8 miles) the bike suddenly begins to miss fire – so badly that it often cuts out, then after a brief rest period it works perfectly, only for a short time before repeating the cycle, on a previous occasion it rode longer each time this cycle repeated but this last time it limped home miss firing.

What I have done so far:
Repaired the rubber hoses to the tank/carburetor section – breather tubes/fuel diaphragm tube, etc
Cleaned the fuel filter & Tank. Install new plugs – the new fancy type that has no adjustable electrode gap overhauled the carburetor (It is now set to run just a little leaner than before). I checked the wires to – the ignition, regulator, coil and plugs. I have reset the primary chain tension by adjusting the nut to give the tension advised in the manual (but I noticed that I had to reset it again yesterday.)

My first suspicion was that I had a fuel supply and control problem!
– since then I have focused on timing & ignition areas. By the time you read this I will have changed the oil and the oil filter. (the level is OK, but oil could do with a change)
Do let me know what you think the problem is.
Thanks for your assistance in advance,
Over & Out

A: George, a few things. First is easy. Make sure that the gas cap is venting correctly. If You put it to your mouth, you should be able to suck air thru it. Next, test your charging system. If that checks out. I would look at your ignition. Make a jumper wire. You will need 1 small eyeloop (for coil terminal), 1 larger eyeloop (for battery positive post), 1 male spade terminal, 1 female, and maybe, 3 feet of wire. Run the wire from the coil post where the white wire was (remove the white wire for now), to the positive battery post. The spade terminals should be in line where you can easily get to them. The spade terminals will be your “quick disconnect”. Ride your bike this way. *Remember you will only be able to turn off the bike by disconnecting the jumper (pull apart the spade terminals). Wiring the coil this way isolates your ignition from the rest of the bikes electrical system. If your problem persists; your ignition is, more than likely, the culprit. If this seems to stop the problem, something else in your bikes electrical system is effecting your ignition system.

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