I have had an issue for a long time. I originally thought it was a fuel issue. I have rebuilt the carb—last year—same issue. This is what happens. If the bike sits for a few days is when this is most pronounced: After starting the bike—which fires off easily—about 1-2 minues into the ride, the bike bogs down like it is not getting fuel—like half power. The sound also changes like one cylinder is lost. I can throttle it UP and it accelerates, sort of, but it is like I am running on half power and it sounds like it is chugging. Then there is a slight pop through the tailpipe (not loud) as it kicks into full power mode and TAKES OFF with an immediate jerk. The change moment there is a jerk like everything is firing nicely and I rarely have the issue again on the ride. Sometimes, I have to turn off the bike and restart.. All wiring on the front end has been replaced—rewired with Deutsch plugs. This used to happen more pronounced before I changed out the ignition switch—but it always happened even with the new switch.

I decided to change out the coil first to see if MAYBE that might be the problem. When I installed—and placed all the wires on it correctly. No start. Maybe a cough and backfire though. So, now I am waiting on a new ignition module and decided to go with the HI-4N.

If I recall, the original came with a sensor and a module screwed to the bottom of the oil tank on these models. I can still see mine barely with a light, and the wires they cut and just left dangling.

 

What year? On my 94 FXSTC, I removed it module from under the seat completely, everything comes through the new HI-4N pickup module in the nose cone.

 

Mine is a 1988 FXSTS. I have an OLD Crane Cams HI-4 on there now.

It looks like the old module cannot be removed without removing the oil tank?

 

I guess I thought the Hi-4 was completely in the Cone??? So, I'm Zero Help...

 

I did not believe they actually make that early unit anymore and when they stopped making them 25 years ago we would leave it in place — most today are in the cone using the brass colored cup not the silver colored one - why remove it its a lot of work when all you me need to do is cut the wires and re configure the harness

 

What is in the nose cone? Oem sensor? If it is, you might want to look under the cover. If OEM, they have a history of some failures.

 

Something new in 1970
'71 on Sportsters..

 

If you had a cough and a backfire, then you had spark. Not sure if your year of bike had the vacuum operated pet ****, but if it did, that could be your problem. Also you might want to recheck the wiring on the coil as if it ran before and now it doesn't you might have them hooked up wrong. It is pretty easy to fry the ignition module in the cam cover by hooking up the wires wrong.

A couple of ideas. Usually if something is electrical related it just plain cuts out. You could get an intermittent spark loss due to a bad plug wire but that would usually happen at idle/low rpm as with the increase in rpm's the spark will jump and fire the plug. Get the bike running and if you have a timing light hook it to the spark plug wires and make sure each cylinder is firing. Fuel flow could cause your symptoms as well.

My bike when I bought it had a version of the H1-4N system that used the stock pickup in the nose cone. I never could get the bike to run right so I replaced the whole ignition system with a Dyna 2000i electronic ingnition. Much simpler, just hook up the wires to the coil and blue wire to the VOES. It was like getting a new bike, it ran much better.

You might want to put it back the way it was and see if the bike will at least run. If it does then you know your problem is elsewhere.

 

Something to look at

https://www.hdforums.com/forum/touri...on-module.html

 

Thought I would update: Problem seems solved.

First let me clear up something I caused by my poor explanation. I had a Crane Cam HI-4 in the bike. I discovered wierd and stray wires coming from under the oil tank and never knew what they went to, until I started investigating this issue. I noticed the original module was still screwed to the bottom of the tank. I trimmed the wires and left it. Will remove it when I remove the tank one day (when I upgrage the oil lines in the future).

At any rate, all my intermittent and odd problems started before I changed the coil. But when I changed the coil, it would not start. The only thing I touched was the wires coming from the Crane HI-4. The casing was HARD. I assumed I busted a wire internally somewhere. I should also add, I had a wierd slow intermittent hesitation on low throttle and like a jerky missing symptom since I had the bike (for over 2 years now). This went with the chug and pop on soon after startup that always happened, but corrected if I kept going, with a JERK and then the bike sounded like it was firing on all cylinders again.

OK, so, I got the HI4N in the mail

I spent yesterday and today changing out the old Crane Cam HI4, adding a deutsch plug for the ignition system ,and I also changed out the ignition switch—I have a new working bar bell type that never seemed to work with the CRane-HI4 for some reason.

I installed it per spec of S&S and even followed their timing instructions, marking the flywheel at TDC so I could shoot the back timing light through the primary cover opening. VERY HELPFUL.

At any rate, she fired right up, and I timed it to the mark at 35 degrees. Then took her out for a ride after putting it all together.

WOW. My bikes moves now. No hesitation, lots of power now, no missing like symptoms. Runs a LOT smoother. Hard to believe an expensive, but small piece like that caused so much of a performance issue.

This HI4 issue of mine is one of those Ignition modules (in the cone) that seem to work, but you know something is off. After I emlinated a fuel problem—rebuilt the carb last year) I knew that it had to be something electrical. The HI4 was the last thing I had on my list. It was hte most expensive is why. I rewired the entire font end last year changing out the stock plugs to Deutsch. Highly recommend btw. Most of the wires were awful, worn, and some lost their casings.

Knowing the electrical on the front end was now ok (new) the problems I mentioned above persisted. But it ran, so I kept riding it with all the little hiccups, until the events that transpired I originally stated in this post.

At any rate: problem solved: It was a faulty intermittent problem with the Crane HI4.