Little bit stumped looking for a few ideas

Hey all, I am back asking for some advice. I have my suspicions but the issue is a little vague and I need to develop a methodical approach so I can narrow down the culprit without taking the whole bike apart heh...

The bike starts and idles fine, I can take it out on the road and things are running good. I go for a while though and I noticed today that the bike starts missing and bogging a little. It happens very erratically. I will notice it and the bike will lose power and then I will pull over and look a the spark plug wires refitting and such and then after I kick it over I can roll on for a while till an undetermined time it happens again. Intervals of this happening are unexpected and there seems no pattern. My suspicion is a grounding fault or something with electrical. I just don't have a solid way to trace it all down.

Anyone have a process that they can share? Am I possibly barking up the wrong tree?

71' engine
JS 32mm PWK flatslides
Power Arc ignition
New spark plugs gapped at .025 BPR7ES
Battery is a little old but it reads like its good. 100% and I can turn on the headlight etc.

I have gone through the electrical as best I can with the ignition leads and such, I solder all the connections I work on but I still have a few of those Lucas connectors.

It seems like it bogs or starts failing to spark the plugs. At least that's how it feels.

I value any and all input, Thanks!

Poor gas venting (tank) resulting in a slight staving feel?

lbridges said:

Poor gas venting (tank) resulting in a slight staving feel?

Click to expand...

Gas venting? I guess I could look there too.

I am wondering the ohm value my spark plug wires should test at too,

Since it clearly sounds like an ignition system, start with the fuel. Is the breather cap vent blocked?

Have you had a look at the plugs after it boggs? What are they telling you. How do the plugs look while underway and everything is running fine?

Under what type of riding does the symptoms appear - motoring in traffic, WOT on the highway? Has a WOT plug chop been done and what does it indicate?

Did these symptoms appear after many changes to the configuration of the bike or was this a gradual change? In otehr words, did the symptoms appear after adding the carbs, ignition etc?

Does turning the headlamp on exasperate the symptoms - could indicate a dodgy battery.

Intermittent water in the fuel? Clogging fuel filter?

I changed alot in the last year. Ignition and carburation. I am a glutton for punishment I guess.


I didn't check the gas tank vent and if its clogged. The issue happens when at speed on highway, not a traffic thing but it could happen at any time I guess.

I have these cool spiral core suppression spark plug wires, how may Ohm should they be showing on the meter? My meter set at 20k is showing .73??!!? it doesn't seem right, aren't I supposed to have 6.xxx?

I hate electrical crap.

1.) What are your plus gapped at? According to the directions they need to be 0.025".

SPARK PLUGS
You must use a resistor spark plug with electronic ignitions. Spark plug gap should be limited to as small as possible, while still maintaining performance.
A wide spark plug gap can cause the following problems: Hard cold starting, misfires during rich or lean fuel conditions, and reduction of upper rpm range.
Initial settings for spark plug gaps should be set at 0.025".

2.) Are you using the Taylor plug wires? Are your caps resistor? The cap set that OB sells look like theirs aren't.

SPARK PLUG WIRES
Choice of spark plug wires is an important consideration when using an electronic ignition system. You must use resistor spark plug wires (carbon core or spiral wound with at least 800 ohms per foot). Other spark plug wires will damage the ignition module and void the warranty!

3.) Are you using a relay to power the ignition? There are a lot of switches, connections, and buttons that you can skip with a relay.

rpatton said:

1.) What are your plus gapped at? According to the directions they need to be 0.025".

SPARK PLUGS
You must use a resistor spark plug with electronic ignitions. Spark plug gap should be limited to as small as possible, while still maintaining performance.
A wide spark plug gap can cause the following problems: Hard cold starting, misfires during rich or lean fuel conditions, and reduction of upper rpm range.
Initial settings for spark plug gaps should be set at 0.025".

2.) Are you using the Taylor plug wires? Are your caps resistor? The cap set that OB sells look like theirs aren't.

SPARK PLUG WIRES
Choice of spark plug wires is an important consideration when using an electronic ignition system. You must use resistor spark plug wires (carbon core or spiral wound with at least 800 ohms per foot). Other spark plug wires will damage the ignition module and void the warranty!

3.) Are you using a relay to power the ignition? There are a lot of switches, connections and buttons that you can skip with a relay.

Click to expand...

.025 yup
the wires that came with my power arc were moroso blue max spiral core emi suppression wires. I want to know the ohm reading i should expect when testing them.

I don't have any relays or anything to the ignition, its wired in as the instructions listed without anything extra done.

So if my tester is set to 20k and my reading is .73 then that's 730 ohms? is this good? The length of wire is 11.5 inches.

I have had a similar symptons on two different bikes. Both times it was a faulty ignition switch. Apparently the vibes while riding cause an intermittant short. Stop the bike, no vibes, it would be fine. The next time it does it try wiggling the key and see if that helps. If it does replace the switch. Intermittant shorts are one of the hardest troubleshooting puzzles out there.

You could try popping the gas cap open to let air in during one of your test rides, Did you install in line fuel filters ? they could also be restricting the flow when you have a higher load on the fuel system. Cj

I would clean the kill switch and take a ride If thats not it I would clean the ignition switch thay can be taken apart with a little common sense.Do one at a time so you know witch one was the problem.

Phil

Norton-Villier said:

I would clean the kill switch and take a ride If that's not it I would clean the ignition switch they can be taken apart with a little common sense.Do one at a time so you know witch one was the problem.

Phil

Click to expand...

I pulled the cover and cleaned the ignition switch mechanism, I also replaced the battery. I don't have a clue how old my battery is, It seemed fine but I will do that and the ignition switch first then keep pushing forward.

I also took apart the gas cap assy and blew air through the breather hole.

I had a zip tie holding the battery in and that was lame so I took this chance to try something new. I placed industrial strength Velcro to the battery bottom and backside. Maybe that will hold...

Thanks for all the tips!

I had similar symptoms a while back and change the battery and now all good. Mine would mis-fire then stop. Then after some head scratching would go again, for a while. I like the idea of the relay in the ignition module power supply, that would isolate a lot of potential high resistance items such as kill switch and ignition key switch.
Good luck
Richard

you mentioning changing the battery hold-down mechanism reminds me of a problem I had once after pulling and replacing the battery. It seems I put enough stress on the wire that the inline fuse holder barely made contact. Mine would just die (not stumble) then come back, but it's something free & easy to check.

I just installed a power arch and was worried about those wires, and all the warnings in the directions about voiding the warranty and such. Fred told me the wires were good, I also called power arch and they said "of corse those wires are good, they got them from me" both parties said they're working on rewording the instructions a tad

I don't know if this is related to your problem or not but I found that when testing the power-arc ignition on my test rig the processor would easily loose sync with the timing disk if there were any runout or play in the end of the camshaft. Each time it would loose sync it would put out miss-timed sparks for several revolutions until it would gain sync again. So you might want to check you camshaft runout and bushing wear if you don't find a simpler cause for the problem. Jim

As mentioned prior that as it sure seems electrical in nature - so the next thing I'd think to check is all the carbo fasteners and balance tube and pilot jet and for water in the bowl.

I had a problem a while ago that had identical symptoms to the ones you are describing .
Mine was blocked fuel filters in the tank and fuel lines , cleaned both and no problem since .
Easy to do and well worth a try .

Well I replaced the battery and re-checked the wiring and also cleaned the ignition switch. After doing this I set out to test ride again. I got about 30 miles away and all was good. Lots of wind but the bike was running flawless. I found my destination and decided to turn around, turned around and headed back . On a long uphill grade I felt the bike studder for a bit. I slowed down about 15mph to 50mph, I reached down to the spark plug wires to give them a giggle, nothing changed... Then I slacked off the throttle and the bog subsided. I This bog lasted about 5-10 seconds. I am convinced it is a loose conneciton or some type of bad ground or something.

I carried on to home the next 20 miles with no problem. My speeds were from 50mph to 70mph and the bike was running great. I have a 19 tooth front sprocket so I am winding out healthy at 70mph heh.

With my power arc there comes a white wire that needs power or if cut off it changes the spark map to something other like an advanced curve or something. I am suspect against this wire as I took my extra slack from the install and tucked it above the dual coil unit. I am still thinking electrical for sure.


The new battery had 1hr of charge before I headed out oin the road as well. I generally dont like to do htis as I think a new battery should be trickle charged for 8 hours before use. I didnt want to wait though so....


I think I understand the stupid bell idea the harley guys have, maybe that is my electrical problem, I need the faggy little bell. Just as a afterthought I remember passing a Harley rider with a tow truck on this ride.

iceteanolemon said:

Then I slacked off the throttle and the bog subsided.

Click to expand...

If there was ever a case for a fuel issue. Have a go at confirming adequate fuel supply.

Once resolved or confirmed adequate then do a plug chop WOT and then do a plug chop WOT when the bike begins to bog.

I also think its fuel. If you look at the fuel cap, you'll see a little hole on the ridge of the metal disk that holds the rubber gasket. That hole and ridge are the vent for the tank. There's a hole on the top of that disk, 180 degrees from the bottom hole on that same ridge. A common occurrence is that vent path gets blocked, either by varnish or by rust, and air doesn't come into the tank to replace the fuel consumed.

You may notice you can go further on a half tank before issues than a full tank (more air in the tank, so vacuum builds up more slowly), or that you can go further at slower speeds than high speed (slower fuel consumption also means vacuum builds up more slowly).

Try cleaning out that vent ridge with a wire (single wire strand off a broken cable works pretty well) and some compressed air. Also check the filter screens on the fuel taps and inside the banjo on your carb

I drilled out the original rivet on my cap to better clean the disk, then tapped the post for re-attaching the disk with a screw.