'76 GL1000 Crankshaft Replacement


Information and questions on GL1000 Goldwings (1975-1979)
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ryannealenglish
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'76 GL1000 Crankshaft Replacement

Postby ryannealenglish » Fri May 08, 2015 11:22 pm



Okay, this is a bit confusing, so I'm going to tell the entire story, provide all the symptoms, and see if anyone can provide me with any information. Thank you so much in advance for any help at all. I'm at my wit's end.

I own a 1976 GL1000 that has been rock solid since I purchased it almost two years ago. It's my first GL so, mechanically, I'm at a loss.

I was riding down the road today and while merging onto the interstate I gunned it to get up to speed. When doing so, I heard a POP. I didn't notice anything on the road that I ran over, so I continued riding. However, from this point further, the bike was not running correctly. I have done a bit of ride-testing and this is what I have found thus far.

The bike is running fine. It idles great. It revs from idle to redline while in neutral and with the clutch pulled in just fine - no hitches there.
The problem is when the bike is under load. When taking off the bike is a big sluggish, but takes off slower than before. As I transition through the gears, around 3k RPMs the bike begins to shudder, almost as if I was taking off from a dead stop and released the clutch too early. In 4th and 5th gear the bike will barely accelerate. Eventually it can attain speed, but it struggles to get there.

My first thought was fuel, however I doubt that it's the carbs for two reasons:
1. For two years this bike has been running flawlessly without even a single hiccup. Why would the carbs suddenly stop feeding fuel correctly after such a great length of time?
2. The bike still idles correctly, revs great when not under load (when the transmission is not engaged) so it doesn't make sense. The top end cycling is not being hindered.

My second thought was the clutch, but I doubt that as well primarily because if the clutch was slipping I would be getting revs but no power. However, I'm not getting the revs unless the transmission is disengaged. Therefore, it cannot be an issue with the clutch.


Here's where the story gets interesting.


I proceeded to call my local motorcycle shop to speak with the resident Goldwing Guru. He told me that he's witnessed these symptoms only twice in his career, and ONLY on 76 GLs. He said that on the "hot cam" early models the crank shaft would actually break in half, but due to the pressure (thanks to their superior construction) would hold themselves together just enough to allow proper turning at low RPMs, but begin to slip at high rpms. When I asked what the remedy was, his answer was that he advised I get an entirely new engine due to the high number of hours required to pull a GL engine, split the case, reassemble, and reinstall the engine.



Does all of this sound accurate, or am I being played? Is this diagnosis feasible? Are there any other diagnoses that could fit my symptoms? If not, is a broken crankshaft something that can be replaced by an amateur mechanic, or should I leave this to the professionals?

Please! I need help! Any and all suggestions are welcome.



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dingdong
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Re: '76 GL1000 Crankshaft Replacement

Postby dingdong » Sat May 09, 2015 6:30 am

I haven't thought this through yet as to what may be the problem but I would be looking elsewhere. That would be the last place I would consider if at all.

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SteveB123
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Re: '76 GL1000 Crankshaft Replacement

Postby SteveB123 » Sat May 09, 2015 7:42 am

If your camshaft is broken, your engine stops. There is no "slip" of a camshaft...if it gets mistimed, pistons meet valves and hard parts break. Sounds like your Goldwing Guru is talking out his ass.
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robb
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Re: '76 GL1000 Crankshaft Replacement

Postby robb » Sat May 09, 2015 8:05 am

Similar encounter with a 1983 Ford F250's 6.9 diesel. Could not have been any more happy with truck until 30k miles when it started loosing top end while towing. Flat ground was OK but hit a hill and loose all momentum. Ford replaced the timing chain and 1 week later the injection system. Idle was great and allow to slowly accelerate without trailer I thought it was getting better. It was suggested that I take truck 70 miles away to a Ford Commercial truck center since the diesel was new to Ford. They put truck on a dyno and could clearly see a lack of power under heavy acceleration. They tested again with 2500 pounds in bed of truck and engine shut down. Upon removal and tear down of engine the crank had twist in half. Five cylinders turning the flywheel while the other three were binding the engine when a load was applied.
Ford did me right, a new truck swap for my trouble.

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Re: '76 GL1000 Crankshaft Replacement

Postby bustedwing » Sat May 09, 2015 4:16 pm

I have heard of the problem you are talking about, but as someone else said that would be the last resort. I would start with a compression test to figure out the status of the engine. If that checks out good, then I would look at how much resistance each spark plug wire has. As the wires age they gain resistance and as you demand more work from the engine( higher rpm ) the spark has a harder time getting through the wire and actually retards the timing instead of advancing like it should be. I hope that gives you some ideas of what to look for. The crankshaft replace is a big job and one that you hopefully don't have to tackle.
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SteveB123
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Re: '76 GL1000 Crankshaft Replacement

Postby SteveB123 » Sat May 09, 2015 5:01 pm

bustedwing wrote: As the wires age they gain resistance and as you demand more work from the engine( higher rpm ) the spark has a harder time getting through the wire and actually retards the timing instead of advancing like it should be.


Whoa. The speed of electricity doesn't change with resistance.
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PoolDude
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Re: '76 GL1000 Crankshaft Replacement

Postby PoolDude » Sat May 09, 2015 7:24 pm

Sorry, I have to say that unless the crank is broken after #4 cylinder all that would happen is the engine would grenade. If it was broken and started slipping then it would soon wear the ends smooth and sit there spinning while making a terrible noise so that would be the very last thing I would look for. Lose of power under load sounds more like fuel/air/exhaust restriction. If it can't breath it can't pull. Look for restrictions in the air box, a choke that isn't completely opening or even a clogged exhaust. In cars those symptoms often point to clogged catalytic converters. Another possibility is the high tension wiring insulation breaking down but that seldom happens all at once and is easily checked by running the engine in the dark and looking for sparking where it shouldn't. Or you could fire it up and have your nosy neighbor run his/her hand over the wires.

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Re: '76 GL1000 Crankshaft Replacement

Postby bustedwing » Sat May 09, 2015 9:03 pm

I like pool dudes Idea, just make sure that you wash your floor first! The rest of his ideas are good. Good luck, ride safe, let us know what you find.
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Re: '76 GL1000 Crankshaft Replacement

Postby tom84std » Sat May 09, 2015 11:40 pm

While your description of the problem is pretty thorough. I'm sure there's a lot getting lost in propagation. You say that things seem fine in neutral or running with the clutch disengaged. This really makes me wonder about the universal joint and the final drive. On your list of things to look at, if you haven't found it yet how about putting it on the center stand. With the transmission in neutral, spin the wheel feeling and listening for anything out of the ordinary. It would really be better to spin the splined output shaft with your hand while the wheel's off. If you feel anything other than smooth rotation, something's wrong there. I've also run mine with the wheel completely off to help locate unusual problems. Unless you find someone who's experienced the exact problem, really best guesses are about the only thing we can offer. This is a very curious problem and I'd like to know what you find.

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Re: '76 GL1000 Crankshaft Replacement

Postby WingAdmin » Mon May 11, 2015 9:30 am

I'm still thinking fuel. A "pop" could be from a lean-running cylinder. If there was a sudden partial obstruction somewhere in the fuel system (most likely a jet) that carb would run lean. Enough fuel could get through to support running under a no-load condition, but when under load, it could not supply enough fuel to run properly, the affected cylinder would quit, and the engine would bog down.

I would check the fuel filter and fuel pump to begin with, they are low-hanging fruit. Check the flow rate to ensure enough fuel is getting TO the carbs in the first place.

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Re: '76 GL1000 Crankshaft Replacement

Postby virgilmobile » Mon May 11, 2015 2:30 pm

I don't know how far you've gotten but the first thing I'd look at is the timing belts and then stick a mirror in the plenum box.Pop the throttle and verify each of the 4 slides do move.
Third is ignition timing.




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