1975 gl1000, cylinders 2 and 4 won't fire


Information and questions on GL1000 Goldwings (1975-1979)
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Jimbo Austin
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1975 gl1000, cylinders 2 and 4 won't fire

Postby Jimbo Austin » Mon Sep 22, 2014 6:00 pm



I am trying to figure out why my wing has been lacking power for the last two weeks and I give up. I have found that cylinders 2 and 4 aren't firing based on both exhaust headers being cool to the touch while 1 and 3 are hot. I've replaced the spark plugs and found 4 was fouled (black) but assumed it is overnight oil sepage from using the sidestand. Spark plug wires have been switched and the issue persists. In a nutshell, it seems to run on all 4 cylinders when it hasn't warmed up yet. Once I've been running for 10 or 15 minutes, power drops drastically and when I check the left exhaust pipe, its barely warm. I've synced the carbs, run sea foam through 2 and 4 fuel bowls, checked for vacuum leaks, replaced plugs and fuel filter, nice blue spark from all plugs when pulled and grounded, bypassed the fuel filter, gas cap is venting, confirmed fuel pump is working, rebuilt petcock and cleaned out tank suction lines. This issue started after a carb syncing at which point the fuel filter and plugs were replaced. I haven't taken the carbs apart as that is beyond my capabilities at this point (this is the first bike I've owned). The bike had an electronic dyna ignition and accel coils installed by previous owner.



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ka4yqi
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Re: 1975 gl1000, cylinders 2 and 4 won't fire

Postby ka4yqi » Mon Sep 22, 2014 9:06 pm

If this is the same coil that is fire both of the cylinders. sounds like it has gotten weak. You may want to change coils and then see what it doing.

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WingAdmin
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Re: 1975 gl1000, cylinders 2 and 4 won't fire

Postby WingAdmin » Mon Sep 22, 2014 9:07 pm

You've verified you have spark, you've got fuel - do they fire if the throttle is opened, or are they not firing no matter the engine RPM?

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HawkeyeGL1200
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Re: 1975 gl1000, cylinders 2 and 4 won't fire

Postby HawkeyeGL1200 » Mon Sep 22, 2014 9:27 pm

ka4yqi wrote:If this is the same coil that is fire both of the cylinders. sounds like it has gotten weak. You may want to change coils and then see what it doing.

1 & 2 share a coil and 3 & 4 share the other one.

I had a similar "thing" happen to me on my 1200 this week, except mine isn't firing on the right side (1 & 3)... I determined my trouble to be fuel pump failure or relay failure... fortunately, I have another MC to ride while I fix the 1200...

I'm puzzled by either a "right" or a "left" side failure to fire... as they don't make as much sense as a shared coil pair of cylinders not firing.
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.

Jimbo Austin
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Re: 1975 gl1000, cylinders 2 and 4 won't fire

Postby Jimbo Austin » Tue Sep 23, 2014 6:51 am

Hi guys, thanks for the interest. The weather is low 70's for the rest of the week and I'm going mental having to be back in a four wheeled vehicle. Once the bike is warmed up, it doesn't matter if it's low or high rpms I get the same loss of power and popping from the left exhaust (2 and 4). Once I get up to highway speeds, I can't seem to get the rpms past 4000 and speed won't go much above 50 or so mph (I read in another post that the gl1000 top out at 50mph on half the cylinders?). I did have it running well after syncing it on the weekend and left the guages attached while I went for a test ride (yes, they sat in my lap while I drove around). I put my vacuum tubes back on and it ran well for another 10 minutes, and then the same old loss of power and popping started. Last night I fired it up after putting a bit sea foam directly in 2 and 4 fuel bowls and it blew smoke for several minutes as it burnt it off, throttle response was there, no popping and then it went back to it's lame state after about 5 minutes while ideling in the driveway. Heat seems to be the enemy here which would make me think it's electrical/ignition and not fuel delivery. Thanks again for the help!

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RBGERSON
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Re: 1975 gl1000, cylinders 2 and 4 won't fire

Postby RBGERSON » Sun Oct 05, 2014 9:14 am

If both 2and 4 aren't firing not the coils if they are hooked up correctly as one coil fires 1/2 and the other 3/4..and 2/4 are the ones on the left side of the bike. Seems like a fuel issue or lack there of...could be a blocked galley in the carbs teh one that goes from #3 to #4 and then to #2. Two bad plug wires?, or caps seems unlikely but could be.
HAD LOTS OF GOLDWING 75-83
NOW INTO 1500'S..RIDING A 1998 SE

FAIR WINDS,
RB

Jimbo Austin
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Re: 1975 gl1000, cylinders 2 and 4 won't fire

Postby Jimbo Austin » Sun Oct 05, 2014 12:19 pm

Yes, plugs and wires were replaced with no change. I'm having the carb opened up this week for some exploratory surgery. I'll update once the patient has stabilized.

Jimbo Austin
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Re: 1975 gl1000, cylinders 2 and 4 won't fire

Postby Jimbo Austin » Tue Oct 07, 2014 11:21 am

Good news! The carbs were all opened up yesterday and all were full of very, very fine particles, likely sediment from the tank or through the air filter (I'm missing a snorkel-like tube off of the front of the air box apparently). The straw that broke the camel's back were the small fuel bowl inlet screens were very dirty, with number 2 in bad shape and number 4 pretty much completely blocked. The mechanic is cleaning everything up and suggested we jet the carbs to line up with PO's previous upgrades to the bike (K&N air filter, Accel coils/dyna ignition, and Harley pipes). I can't wait to get it back as there are a few decent weeks of riding left before the snow starts to fly.

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WingAdmin
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Re: 1975 gl1000, cylinders 2 and 4 won't fire

Postby WingAdmin » Wed Oct 08, 2014 3:10 pm

Perhaps replacing the K&N might help - they aren't exactly known for being the best at filtering particles out of the intake airstream (pretty much the opposite - they usually test as the worst).




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