Spark plugs

[Bombasstic]

I have had a few Spark Plug fails on late. Even new plugs. I start feeling some "spluttering" under load going up hill.
After hunting and testing the failed plug I find no continuity from Terminal to Center Electrode.
I have tested my Coils and HT wires and have the correct Ohm readings - Primary and Secondary.
Could some kind of "power surge" damage a plug - if so, what could be a possible cause?
I have been advised to use High Performance plugs as the plugs of today are too "mamby pamby" for bikes of yesteryear ? ? ?
I am using NGK D8EA at the moment.

Any input will be appreciated.

[WingAdmin]

That plug should be fine for a GL1100. Most common failure for plugs is heat damage. Are you torquing the plugs correctly?

Are you seeing the plugs actually damaged - cracked, etc? Does the "spluttering" go away with new plugs? Have you tried re-gapping the plugs and see if the spluttering goes away?

[Bombasstic]

Hi, Thanks for your input. When I baught the plugs I was told they were manufactured and gapped to spec so I didn't bother gapping them. I have now taken them out and found the gaps to be on the outer limit (0.7mm). I reset them to 0.6mm and problem solved. She purrs like a kitten even under strain. THANKS from S.A.

[blupupher]

There have been issues with "fake" sparkplugs, especially from Amazon and e-bay.
Usually if you get from a brick and mortar store you are good.

[WingAdmin]

I always re-gap "pre-gapped" plugs because I often find that they are out of spec when I get them. Glad to hear you got your problem solved!

[Bombasstic]

I thought I had it sorted but sadly not. Number 4 keeps fouling up even after a very short ride. "Identified by black,dry fluffy carbon deposits" Rides beautifully . . . then starts spluttering and missing . . . clean plug and all good to go for a while. And it's only Cylinder 4.
"Weak ignition" I have checked coils and and leads, all good with correct ohm readings.
"Too rich fuel mix" I stripped and cleaned jets etc. in carb 4. All good
For good measure I reset the tappets. Still no joy.
Question - The pilot jet sets air fuel mix . . . but is this only at idle? As far as I understand, once riding, the pilot jet is then a non event as it is bypassed. If I am wrong . . . would turning the pilot jet in on number 4 give me a leaner mix while riding. ?

[Rambozo]

The idle jet and mixture screw is pretty much only for idle. It does meter fuel throughout the rpm range, but it's contribution above idle is minimal. You might want to check the main jet and needle. Measure the jet with a pin gauge or number drill and compare it to one of the others. Same with the needle. Compare the free length and wire diameter of the slide springs. Basically, keep your eyes open for any differences. On old bikes you never know who has done what. Double check float level and weigh the floats. Something is making that cylinder too rich. Make sure all the air bleeds are open.

[Rednaxs60]

My '85 is an FI model, but have looked into the 1100 OEM service manual regarding carbs because I think an 1100 or 1000 GW would be a good project. I have read that there is one carb used as the base, #3 - cannot be adjusted, and the remaining three are synchronized to this carb. Once you get through the checking for various carb components, do a carb synchronization. Good Luck.

[Bombasstic]

Hi, Watched a youtube clip re the setting of the float and how it can cause lean or rich mix.
Took carbs off and compared float setting of 2 and 4. Found both to be adjusted the same. Swapped 2 and 4 floats and took a test run. Still number 4 fouls up.
Going to do compression test tomorrow . . . holding thumbs I don't find burnt valves. Oh well, at least I will know what I am dealiung with.

[Bombasstic]

Compression tested all good +- 170psi. Problem can only be in #4 carb. Could a stuck Air Cut off valve be the problem creating a Rich mix?

[donmainier]

I have a 76 Gl1000. All of my carb problems of late have been vacuum leaks at the rubber boot between the intake manifolds and the carbs. I tightened them while hot and fixed a few of the problems. Then I put a thin coating of silicone gasket maker inside the boot and changed the O-rings at the heads. Then I tightened them while hot a number of times. Now I have no vacuum leaks and my#1cylinder is not giving me any more problems (my problem was always with the #1 not the #4). It runs better than it ever has! I've owned it for 6 years or so. I only recently got it straightened out.

[msgoodwrench]

This sounds like my '83. New plug, runs great for a short time, then starts losing power going up hill, missing...only #3 cylinder. I went thru all kinds of carb fixing, coil checking. The problem I finally found; the plug wires and caps on mine were actually separate pieces. When I took the #3 plug wire and cap assembly apart, there was definitive corrosion there where the plug wire was 'screwed into' the cap. I cleaned that all up and it ran fine after that.

[Bombasstic]

Thanks, will have a look at the wires.

[grahamlang]

the adjuster screw between cyl 1 and 4 carb is to sync that pair together. the adjuster screw between cyl 2 and 4 syncs them together. the ajuster at the rear of no 4 is to snc1 and 3 to 2 and 4. so you sync the right side then the left then sync the two sides. thats the way i was told and shown when i attended the technicians course all those years ago. as for the plug gap causing funny running why isnt it affecting the other cyls. you say you have cleaned the jets. if the jets were blocked it would run weak. the fact its fouling the plug says its rich. you need to check all the air passeges are clear. including the 4 plenum chamber feeds to the slow running jet. good luck. post what you find.

[Bombasstic]

Mind is boggled. Stripped the carbs again. Cleaned and blew out every jet and hole. Fitted new air cut off valves, accelerator pump, float needles . . . all good. Start up and idle is good. Firing on all 4. Go for a short ride and as soon as I get to 3000 / 3500 rpm she starts spluttering.
Inspect and find 3 plugs good but #4 is coated with black soot.
Believing the carb to be good, I swop HT leads . . . still same. Swop coils . . . still same. Swop spark units . . . still same result. #4 plug is sooted after short ride.
IT CAN ONLY BE THE CARB - but what???
I have swopped carb #3 and #4 Main jet, Float, Pilot screw, Jet needle . . . still same result. #4 plug is sooted.
The one thing I can't confirm to be clear is the idle jet (is that what you call the slow running jet?) I have cleaned and blown out the best I could but it is pressed in and non removable. I doubt that this could be the problem . . . but hey, I'm open to anything at this stage.

[OldguyGlen]

Maybe it's oil fouling the plug. Left side exhaust smoking? Valve seals, or bad rings. Just a guess...phantom problems can really be frustrating.

[Fatboy46]

ALWAYS gap your plugs... consider that they come in a small box. They get loaded up in bulk. They get dropped on workbenches or into the sack at the parts store. and maybe the tool they used at the factory is worn out?

[Tparr]

I thought I had it sorted but sadly not. Number 4 keeps fouling up even after a very short ride. "Identified by black,dry fluffy carbon deposits" Rides beautifully . . . then starts spluttering and missing . . .

my Initial thought is oil fouling like Oldguyglen mentioned. How about taking a picture of the fouled plug and sharing it with us.

[Bombasstic]

I thought I had it sorted but sadly not. Number 4 keeps fouling up even after a very short ride. "Identified by black,dry fluffy carbon deposits" Rides beautifully . . . then starts spluttering and missing . . .

my Initial thought is oil fouling like Oldguyglen mentioned. How about taking a picture of the fouled plug and sharing it with us.

Thanks for reply. I have taken the heads off just to make sure that there are no valve problems. There aren't.
I will post plug pics as soon as I've got her running again.

[Tparr]

It sounds like you have been through the carbs numerous times so I'll rule that out for now.
Compression test of 170 on all four cylinders is very good.
You pulled the heads so any sign of oil fouling or a coolant leak would be obvious.
Did I miss that you performed a vacuum synchronization?
Let's look at the ignition a little closer. Swap the spark plug wires for cylinders 3 and 4 and see if the problem follows the wire. Are you using the original coil and wires and caps?

[Bombasstic]

Unfortunately, I need to wait +-30 days for my Top End Gasket kit to arrive before I can put it all together again.
In the intrim I am cleaning up everything I can . . . Checking all wiring . . . Derusting the gas tank (if needed).
I am not going to touch the carbs (again) as yet.

I did all the tests of swopping coils, HT wires etc. Confirmed that the Compression is good. Checked tappet settings. Now checked Valves.

I will do all the swopping again when I've got it all together . . . and if I find the same result . . . I am back to the carb ?

Thanks for input

[Tparr]

While you have the engine out replace the timing belt, check/replace the coolant pump and check the stator. Also a good time to clean and inspect the mechanical advance unit and pick up coil.

[joecoolsuncle]

while waiting, order OEM main jets and float valves. you never know what or who have deviated from stock. immediate fouling at 3K rpm, but nowhere less, is indicative of only one thing. too much fuel or two little air.
if it was ignition, it would foul at least two plugs.
if it were oil, it would nt be rpm sensitive
if it were air, it would be across all cylinders
if float or float valve, it would be worse at lower rpm, better at more rpm.

it is carburetion on one cylinder only (based on info you hve given).
main jet loose? needle jet worn? jet needle worn? diaphram spring missing/broke/weak?
most likely.........main jet too large, needle and or jet worn.
peace

[msgoodwrench]

I had 'ignition' problem on my '83 Aspencade, only fouled ONE plug - #3. It was corrosion in the connection between the cap and the wire. That is a vulnerable place, just basically screws together, and there was green corrosion in there!

[Bombasstic]

Thanks for all replies. Appreciated.
As soon as I've got it all together, if the problem persists then it can only be the carb.
I will then swop single carb components one at a time until I find the problem has moved to another cylinder.