Intermittent loss of power

[CatatonicBug]

How long do plugs usually last? I'd guess I'm up to 20k miles on these.

[BA80]

Irridiums should last for just about ever but being exposed as they are on a bike could change longevity considerably.

I don't suppose you have an old set of ANYTHING you could stick in there just as a test?

[CatatonicBug]

Nope... Maybe I should go and buy a set of cheapo plugs to test with. $12 for all 4 might be worth it for troubleshooting.

[BA80]

Pull your plugs and take a look at them. Very possible you can get a clue there. If 1 or 2 show evidence of gas fouling move them to a cylinder that looks normal. If the problem follows the plug, it's the plug. If not you're still looking.

[motoman]

I have been chasing my tail on this one, so before I go and spend more money to replace parts that might not need replacing, I figured I'd ask the collective mind...

Bike starts fine, idles fine, and even runs the freeway fine - most of the time. It seems that lately, I'll be tearing down the freeway, and I suddenly feel like I'm running on 2 or 3 cylinders! I can maintain about 70-75mph on flat ground, but no more than that. It will drop out, then return, sometimes a few times per second. Usually, the problem lasts for several seconds to many minutes (i.e., the rest of my ride home). If I turn off the bike, and restart, the problem will go away for a few seconds, then return.

There is no correlation to speed, or RPM, as this has even happened in a parking lot. It does seem to wait until the engine is fully warmed up though. I have taken the TCI apart and re-sweated the contacts, I have cleaned all the terminals on it too. I did notice that my battery will need to be replaced soon, as I let it dry out this summer...

My only thoughts at this point are:
1. Might the dying battery cause this? I doubt it, since it is so intermittent, with the same AMOUNT of power lost all the time.
2. Am I missing a different loose connection somewhere?
3. Possibly a spark plug going bad? At $14/ea, I don't want to replace them AND the battery if I don't need to.

Any thoughts or insight would be appreciated.

Haven't read thru all responses, but I believe a voltage drop to coils is taking place. I would remove and carefully disasemble kill switch as it complets the circuit while running besides acting as a shutdown function, I'd remove it carefully so tiny spring doeasn't fly off looking for a new home. drop all pieces including swirch itself in a cup of Evapo-Rust overnite. Remove and wash pieces off with water and dry. Rs for creating a voltage dropp Reassemble and install. This piece IS notorious for a voltage drop location, as are the coils when they get hot. May wanna check ohms across the two poles of each coil to see if they meet ohm specs. Check that voltage to coil plug-ins are samw 12+ volyge with key on also.

[BA80]

Haven't read thru all responses, but I believe a voltage drop to coils is taking place. I would remove and carefully disasemble kill switch as it complets the circuit while running besides acting as a shutdown function, I'd remove it carefully so tiny spring doeasn't fly off looking for a new home. drop all pieces including swirch itself in a cup of Evapo-Rust overnite. Remove and wash pieces off with water and dry. Rs for creating a voltage dropp Reassemble and install. This piece IS notorious for a voltage drop location, as are the coils when they get hot. May wanna check ohms across the two poles of each coil to see if they meet ohm specs. Check that voltage to coil plug-ins are samw 12+ volyge with key on also.

Do you have that response in a file somewhere and just copy and paste it Brant?

[skids]

Any thoughts or insight would be appreciated.

Try this: When the bike drops a couple of cylinders, try switching the petcocks to prime.

[jwhughes3]

I may have missed your response but did you test the pickup coil wires? Tugging gently along them while idling to check for a break?

Sure sounds like what happened to Great Ranger when those pickup coil wires went bad.

John

[ViperRon]

I have had my pickups fail before and it acted just like this before you work on something that is not broke get a meter and ohm those pickups while moving the advance back and forth. It will probably be best to warm up the bike first. Check them at the TCI you may have a connection in-between bad. The connector can build up with road scum and develop a intermittent short or wires in the harness can crack and moisture can get in and do the same.

[Eveready1100]

Pull your plugs and take a look at them. Very possible you can get a clue there. If 1 or 2 show evidence of gas fouling move them to a cylinder that looks normal. If the problem follows the plug, it's the plug. If not you're still looking

If you check what Greg has suggested, and there's no sign of fuel fouled plugs, have a look at the fuel cap breather. If it's starting to clog up, it can make the motor start to misfire as it's starving for fuel.

[dbeardslee]

I have had my pickups fail before and it acted just like this before you work on something that is not broke get a meter and ohm those pickups while moving the advance back and forth. It will probably be best to warm up the bike first. Check them at the TCI you may have a connection in-between bad. The connector can build up with road scum and develop a intermittent short or wires in the harness can crack and moisture can get in and do the same.

If you're going to check the resistance on your pickups you should do it cold to insure they're in spec. When the bike warms up the resistance will rise maybe 100 ohms, which can freak you right out if you're not ready for it. DAMHIK

[CatatonicBug]

Ok, a few new pieces of info for you guys to chew on.

I warmed up the bike, and as I was taking the seat and lowers off, the problem began. So, I decided to pull the plug wires to see which plugs were the problem. Turns out, it was 2&3 - Both of them.

Took the plugs out, they all look pretty. No difference between them. So I put them back in, and switched the plug wires to see if the problem moved with the wires. I then remembered that I had to swap the power leads to the coils as well. So, that means the 1&4 coil is now running 2&3, but the power leads remain with the original cylinders. The problem did not move! This means the coils and plugs themselves are NOT the problem, but the power going to them.

This is where I get stuck. I traced the problem to the gray wire coming from the TCI. I went so far as to de-solder and re-solder the posts for that AND the orange wire (the one for the other coil), but while the problem was gone last night, it was still there this morning when I started it up to head to work.

Does this help anyone in the diagnosis? I could not find a connection with a gray wire in it behind the fuse panel.

[dbeardslee]

That's sounding more and more like a problem in the pickup circuit - either in the wires or the thing that sends the signal to the wires - the TCI. I'd check the resistances from the tci and see if they change when you jiggle the wires around at the pickups. I've got a spare TCI that I'd let you use for diagnostic purposes, but unfortunately it's a 2H7-10 and you probably need the 4RO.

I had another problem on Betsy years ago that was sort of similar. Down where the wires come out from the timing cover there's a factory splice inside the gold colored sheath - close to where the wire for the neutral switch comes out. Oil had run down the side of the motor and gotten inside the sheath and was shorting things out. That one's kind of a long shot, but I mention it anyway.

[CatatonicBug]

Ok, I have replaced (spliced) several sections of wire coming out of the timing cover, but that's all I've ever done. Honestly, I don't know how to go about checking the resistance. All I know is that there are several wires that come out of a rotating, spring-loaded device, actuated by suction from carb #2. I don't understand the "magic" behind the pickup/timing circuit in the least.

If someone can give me detailed instructions (pictures help, if possible), I will dig into this again tonight.

[dbeardslee]

Just pull the four wire connector off the TCI, and connect a DMM to the contacts inside the connector. They're in pairs - two wires go to one pickup and the other two go to the other pickup. When the bike is cold you should get a reading of 720 ohms, plus or minus 15% IIRC. When it's warm the reading could be up around 850 ohms, so it's best to do it cold.