78 gl1000 cylinders 2 and 4 not working


Information and questions on GL1000 Goldwings (1975-1979)
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philmore
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Joined: Tue Jul 29, 2014 7:10 pm
Location: Hamilton, Ontario, Canada
Motorcycle: 1978 gl1000

78 gl1000 cylinders 2 and 4 not working

Postby philmore » Wed Jul 30, 2014 9:15 pm



hi I new to this form , I am looking for help solving a problem with my GL1000. The cylinders 2 & 4 are not contributing. Exhausts on cylinders 1 & 3 are hot when running.2 and 4 are warm. The spark is available at all cylinders. Compression is 120 on all four cylinders. Cylinder leakage test is good. CAM timing is on the marks. Carbs have been cleaned and new O rings fuel is present when I crack the drain plugs when running.I get some backfiring through the intake and exhaust on left side.this is the way I picked the bike up I don't have much history on the bike other than the timing belts where changed at 47960 km in 2011 and only has 30 km since.This lead me to think timing issue but i have triple checked the marks they line up ok compression is a little low but even and 1 and 3 work.
I have inspected the cylinders with a camera no faults found.The ignition system is a martech electronic pickup so no points.
the coils are oe the resistance of the high tension wires are around 25000 ohms. I leaning toward a coil replacement but the way the system works doesn't make sense .Any thoughts on this problem would be greatly appreciated.



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Placerville
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Motorcycle: 1976 Naked Yellow

Re: 78 gl1000 cylinders 2 and 4 not working

Postby Placerville » Wed Jul 30, 2014 10:08 pm

philmore wrote:hi I new to this form , I am looking for help solving a problem with my GL1000. The cylinders 2 & 4 are not contributing. Exhausts on cylinders 1 & 3 are hot when running.2 and 4 are warm. The spark is available at all cylinders. Compression is 120 on all four cylinders. Cylinder leakage test is good. CAM timing is on the marks. Carbs have been cleaned and new O rings fuel is present when I crack the drain plugs when running.I get some backfiring through the intake and exhaust on left side.this is the way I picked the bike up I don't have much history on the bike other than the timing belts where changed at 47960 km in 2011 and only has 30 km since.This lead me to think timing issue but i have triple checked the marks they line up ok compression is a little low but even and 1 and 3 work.
I have inspected the cylinders with a camera no faults found.The ignition system is a martech electronic pickup so no points.
the coils are oe the resistance of the high tension wires are around 25000 ohms. I leaning toward a coil replacement but the way the system works doesn't make sense .Any thoughts on this problem would be greatly appreciated.


A question: You said, "the resistance of the high tension wires are around 25000 ohms." What are 'high tension wires?" Are you referring to your spark plug wires? If so, plug wires should have zero resistance and (new) spark plug caps should have no more than 5K ohms. From your description, it seems you have a weak spark on both #2 and #4.
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HawkeyeGL1200
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1981 GL1100 Interstate

Re: 78 gl1000 cylinders 2 and 4 not working

Postby HawkeyeGL1200 » Thu Jul 31, 2014 6:42 pm

Another member had the same problem a few days ago. He discovered water had pooled in the spark plug recess because the drain hole was plugged.

I'm not implying this is what is giving you trouble, but it is worth a look.
I am wrong as often as I am right concerning what is wrong with someone else' motorcycle without having seen the machine in person. Guessing with limited information, as to the source of the trouble, is sketchy at best.

philmore
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Location: Hamilton, Ontario, Canada
Motorcycle: 1978 gl1000

Re: 78 gl1000 cylinders 2 and 4 not working

Postby philmore » Thu Jul 31, 2014 8:11 pm

to pacervilles question my bike has coils and wires as one unit I measured resistance through the caps wire and coil.from the specs I found you are right each cap is about 5000 ohm and the coil with wires about 14000 ohms . I have looked for spark leakage even soaked coils and wires with wd40. If I start it with 2&4 wires with spare plugs grounded to the head they fire. I have spark compression and I believe fuel even went as far as introducing propane into the balancing ports of 2 and 4 no rpm change.
this is a real head scratcher anybody have any ideas thanks guys.

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Placerville
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Re: 78 gl1000 cylinders 2 and 4 not working

Postby Placerville » Thu Jul 31, 2014 10:52 pm

philmore wrote:to pacervilles question my bike has coils and wires as one unit I measured resistance through the caps wire and coil.from the specs I found you are right each cap is about 5000 ohm and the coil with wires about 14000 ohms . I have looked for spark leakage even soaked coils and wires with wd40. If I start it with 2&4 wires with spare plugs grounded to the head they fire. I have spark compression and I believe fuel even went as far as introducing propane into the balancing ports of 2 and 4 no rpm change.
this is a real head scratcher anybody have any ideas thanks guys.

Testing through your coils at the wire ends (and not through your caps) should result in 14000 ohms, just as you have.
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Old Fogey
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Re: 78 gl1000 cylinders 2 and 4 not working

Postby Old Fogey » Thu Aug 07, 2014 5:23 pm

#2 and #4 are run from different coils in any case, so tain't thems.

The only thing that can affect 2 & 4 equally is the cam timing on that side. Or slightly possible, a blockage in the fuel cross-plenum port.
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'Impossible' is just a level of difficulty! The only stupid question is the one you didn't ask first!

philmore
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Motorcycle: 1978 gl1000

Re: 78 gl1000 cylinders 2 and 4 not working

Postby philmore » Sun Aug 10, 2014 7:21 am

just an update I inspected valve timing/cam pulley marks again and removed the cam gear to check the key way .So I started it still ran on 1 and 3 checked compression all were the same 120 psi .I know its low but the bikes been sitting for years . As it runs it was popping back through # 4 intake if I pull the plug wire the popping stops . I pulled the plugs and intake runners on 2 and 4 set the valves to closed on 4
filled the intake port with brake clean to see any leakage past the valve seat the fluid level didn't drop.As a last resort I used the compresion gauge hose and applied air to the cylinder and bubbles appeared in the intake. So the head is off now and valves are out if they are bent its difficult to see . The seat looks shiny all the way around the valve and head .More testing to come I guess . Thanks guys for your input .

Jimbo Austin
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Re: 78 gl1000 cylinders 2 and 4 not working

Postby Jimbo Austin » Sun Sep 28, 2014 9:16 am

Hi philmore, did you figure this one out? I have been suffering from the same issue (2 and 4 appear to not be firing, spark and gas is getting through).

philmore
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Joined: Tue Jul 29, 2014 7:10 pm
Location: Hamilton, Ontario, Canada
Motorcycle: 1978 gl1000

Re: 78 gl1000 cylinders 2 and 4 not working

Postby philmore » Sun Sep 28, 2014 7:01 pm

jimbo yes after reseating the valves with lapping compound new valve seals it still was the same!
As I was rechecking every thing I took the rotor off the cam and turned it 180 degrees and 2 and 4 started to fire but 1 and 3 quit
it doesn't make sense as to the wasted spark system .long story short I ordered a dyna s and all 4 cylinder fire now.The old ignition was a martech not much information on this system on the net. The carbs need to be synced but Im going to remove the engine to paint it and the frame first .Hope this helps best of luck with yours.




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