weak spark, what to check? UPDATE, problem identified

[elwood440]

After the full restoration, I noticed some strangeness in running, but not knowing better figured it was just "how it is." I've finally gotten a long ride (not just around town) to spend some time on the bike and get a feel for exactly what's going on and I think it's not right.

WHAT IT'S DOING:
The first thing I noticed after rebuild was the lack of "buttery smoothness" that I've read so much about goldwings having. There is definitely an engine vibration. That is, until I "give 'er the beans." At that point it smooths out and away we go! (usually) After the longer ride, I did notice that there is a certain speed/RPM where at steady throttle and speed, it will actually surge and flip back and forth between "smooth" and "not-smooth." Also during the ride, there was a LONG straight road with no traffic, so I tried out a high speed run. From 60 in 5th gear with the throttle WFO, it got to 90 and was sloooooowly ticking up before I had covered a LOT of ground and I let the group catch up. Not the result I figured on. Seems like 100 should come and go fairly easily. The other thing it's doing is it needs a good 5 count of cranking before it will start. Once in a while it will fire immediately but not catch, then it needs a 4 count or so before firing again. The starter is STRONG and fast, and once it does start, it warms up and runs as you would expect. ..well, other than the smooth/not-smooth thing.

WHAT WE'RE WORKING WITH:
-79 GL1000
-Carbs expertly rebuilt by Pete and Moose with new vacuum cap buttons. (I'm super confident this is not carb related)
-Used Dyna S and green 3ohm coils from a donor bike. It is evident that the donor bike was "rode hard and put up wet."
-Jumper wire in place of ballast resistor
-ALL electrical connections cleaned and greased at rebuild. (ALL of them)
-All grounds clean and tight
-R/R replaced with modern FH008 unit. (13.4v at idle, 13.8v at 5k. Seems about .2 low, but the battery seems to be happy)
-Brand new NGK DR8EIX plugs, new NGK XD05FP caps with brass rod intead of resistor, new metallic 7mm plug wires, new coil end wire snap clips crimped AND soldered.

WHAT I SEE:
-I haven't looked at a lot of spark plugs, but to my uneducated eye, the spark looks thin and dim all around
-Pulling ANY one plug wire makes no noticeable difference at idle.
-Pulling 1 AND 3 changed the sound and rpm, but it still idled nicely.
-Pulling 3 AND 4 had the same effect. 2-cylinder idling nicely.
-While balancing carbs, vacuum seemed to always be wandering. I got it as close as I could and called it good.
-It will idle at 800 rpm, or possibly lower, but sounds like a rock tumbler when it's that slow. It's not until ~1250 that it gets smooth. Carb balance didn't help.
-doesn't start quickly.

WHAT I'VE CHECKED:
-Coil/wire/cap resistance (don't remember value, but it was within spec.)
-Fuel cap venting correctly (rode with cap off, no change)
-Static timing is dead nuts.
-Probing around intake and carbs with unlit propane torch had no effect on idle.
-~38MPG
-running 87 octane, and e0 when possible. Other flavors don't seem to make any difference in running.

WHAT I'VE DOUBLE CHECKED:
-Belts lined up with marks.
-Valve lash is .004 all around.
-Plugs are a lovely tan color
-Compression is ~70psi all around <edit>NOT 70psi, 150psi. I'm an idiot.
-Leakdown held 75-77 at 80psi

WHAT I'VE TRIPLE CHECKED:
-Coil wires connected correctly, primary, secondary, l/r, 1-2-3-4.
-Header temps are always within 20-30 deg of each other. (measured with IR thermometer)

WHAT I'M NOT 100% CONFIDENT ABOUT:
-Advance unit is free, but I learned later that they are not supposed to be lubed, and I used grease on it. This wouldn't explain the surging though.
-I also learned after restore was complete, that the 75-77 advance unit is different from the 78-79 unit. One of my parts bikes is a 76, so I'm not 100% which one was installed.
-Fuel pump effectiveness. It seems to be working, but I'm seeing a stain around the diaphragm screws on top, so it may be leaking ever so slightly. Also, the large clear fuel filter is never more than about half full. I imagine that's normal. But a under-performing fuel pump would probably only cause a problem at high throttle right?

[elwood440]

I always try to make these things short and sweet, and then I look up and I've written a novel. Sorry about that.

[CYBORG]

The compression numbers you stated seem a little low to me. Was it done with wide open throttle?

[Whiskerfish]

If you are pulling plug wires and there is no change at idle then odds are very high it is not idling/ hitting on all 4. Start it up from cold and if you have an IR gun or access to one use that on the headers. If not use a mist spray bottle of water and check the header temps for evenness.

[CYBORG]

Often the spark might LOOK weak... But if you are in doubt, hold the end of the wire while cranking If the color is blue your good.

[Whiskerfish]

My poor little brother. For years I abused that kid with spark plug wires while I was kicking over bikes. I think he still hates me to this day about that.

[CYBORG]

Have to say, I've been bit a time or two. Usually by a bad wire,... or wire end

[Track T 2411]

I agree that the compression numbers are low. Anything under 90 psi is most certainly going to affect performance. I'm also curious why you removed the resistors from the plug caps. Not that I'm much of an ignition master, but I've read that the resistor helps 'shape' the strength and duration of the spark.

[CYBORG]

I agree that the compression numbers are low. Anything under 90 psi is most certainly going to affect performance. I'm also curious why you removed the resistors from the plug caps. Not that I'm much of an ignition master, but I've read that the resistor helps 'shape' the strength and duration of the spark.

Don't know about that, but I run molded automotive wires, (no resistors), and the spark is strong

[RB]

70 is WAY low..manual recommends rebuild below 140..I'd say that's youir problem..bad rings, bad valve/seats..weird they are all 70..testing with throttle wide open, all the plugs out, bike warm or cold??, Also weird that is runs Ok with two cylinders unplugged?? one OK but two..should sound really bad.

[robin1731]

I agree with those low compression numbers. Did you do a leakdown after that? That should have been the next step with numbers that low.

.

[gltriker]

I agree that the compression numbers are low. Anything under 90 psi is most certainly going to affect performance. I'm also curious why you removed the resistors from the plug caps. Not that I'm much of an ignition master, but I've read that the resistor helps 'shape' the strength and duration of the spark.

Don't know about that, but I run molded automotive wires, (no resistors), and the spark is strong

good reading material, from Mike Nixon's library.
http://www.motorcycleproject.com/text/plugwiretech.html
Nothing is mentioned about added resistance promoting spark shaping and duration, though.

[elwood440]

Sorry, I'm an idiot.

My crusty memory was digging up differential test numbers. Straight up compression (can't find where I recorded the exact numbers right now) was more like 150-155. I did a full valve job during restoration, If I got 70 I would have failed miserably.

IMG_1955.JPG

If you are pulling plug wires and there is no change at idle then odds are very high it is not idling/ hitting on all 4. Start it up from cold and if you have an IR gun or access to one use that on the headers. If not use a mist spray bottle of water and check the header temps for evenness.

I regularly use my IR gun to check header temps and they are always within 20-30 degrees of each other. I agree though that it seems like its not hitting all four, but header temps and spark plugs all read the same.

When I pulled plug wires, the results are the same for ANY wire I pulled. I pulled all four, one at a time, and none of them seemed to make a difference I could detect. Only after I pulled a second one off could I notice a difference.

[elwood440]

I agree that the compression numbers are low. Anything under 90 psi is most certainly going to affect performance. I'm also curious why you removed the resistors from the plug caps. Not that I'm much of an ignition master, but I've read that the resistor helps 'shape' the strength and duration of the spark.

Don't know about that, but I run molded automotive wires, (no resistors), and the spark is strong

I removed the cap resistors because I'm running resistor plugs. The wire is automotive copper core (non-resistor) wire.

IMG_2012.jpg

[CYBORG]

I read it, and take from it two things. The automotmotive type wire I use has the resistance built in, so the resistor in the cap is not needed. And that Automotive wire should not be used. I agree with the first, but in my case, I have to take issue with the second. I have an automotive type system. (C5) on my 78 and it is an engineered system that works flawlessly. And the 1200, with stock ignition, using automotive wires, also works flawlessly. Many thousands of miles on both. But I ride for the ride. Not to listen to a radio. And parked, running, next to my cars and trucks, cause no problems with reception. Back in the day of AM Radio it was more of an issue. Not so much with FM