GL1200 I Poor Power


Information and questions on GL1200 Goldwings (1984-1987)
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mainer4
Posts: 8
Joined: Tue May 21, 2013 10:56 am
Location: Limington, Maine
Motorcycle: 1985 GL1200 Interstate

GL1200 I Poor Power

Postby mainer4 » Tue May 21, 2013 11:46 am



Just bought my wife's dream bike, a baby blue GL1200 with 40K miles on it and in excellent physical condition. Went for a ride on Mother's day and I was quite disappointed in the bike's performance. I have owned SOHC 750's for many years and my current ride is a beautiful '75 Supersport that could so leave this GL1200 in the dust. So I know the 1200 is not running right, I could hear occasional small backfiring at up to 45 MPH. Idles well once warmed up but just goosing the throttle it doesn't sound right and on the road trying to accelerate it acts like it is running on 3 cylinders and sounds thumpy. The harder you accelerate the thumpier it gets. Pulled the plugs and noted that front fight cylinder's plug looks varnished yellow on the electrode while the other three look normal tan color. Compression check confirms all 4 cylinders are within 5PSI. Close inspection of carbs indicates that a vacuum line is disconnected from the suspect cylinder. All 4 carb intake manifold clamps are very loose. Reconnecting the line and tightening the clamps makes no difference in how the machine runs. (New gas btw and cleaned all 4 plugs). Same backfire. Possible bad spark or lean carb condition I suppose. Played with the sync on that carb bank but no difference with +/- 1/2 turn. Exhaust pipe is hot though, so it does seem to be firing, but the pipe is not as hot as the other one on the same bank. I am thinking of swapping plug wires to see if that makes a difference since the plug swap made no difference to start with. I read in the manual that timing is not adjustable and the valves are hydraulic so assume no adjustment possible there either. Hate the idea of jumping into a carb cleaning expedition, but what else? Wingadmin has a carb rebuild article, but how to find it - is there a link?



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virgilmobile
Posts: 7663
Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
Previously owned
78 GL1000
81 GL1100
82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: GL1200 I Poor Power

Postby virgilmobile » Tue May 21, 2013 3:02 pm

Couple of things...The 'sync'screw.....was it the sync adjustment screw between the carbs or idle mixture adjustment on the side of the carb....?

Next,run the bike in second gear and hold it around 2500 rpm...Slowly operate the "choke" lever...See if it smooths out.....It may be fuel starved.
Different color plug indicate a different running condition.A lean condition...perhaps a partially plugged jet.

By the way,my 84 was the same way....just poorly.....After tending to the carbs....it was a hard pulling rocket smooth from idle to red line.

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virgilmobile
Posts: 7663
Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
Previously owned
78 GL1000
81 GL1100
82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: GL1200 I Poor Power

Postby virgilmobile » Tue May 21, 2013 3:09 pm

Also..."search" gl1200 carb (advances forum search).....it yeilds many hours of reading...
Even mine...viewtopic.php?f=5&t=9179

mainer4
Posts: 8
Joined: Tue May 21, 2013 10:56 am
Location: Limington, Maine
Motorcycle: 1985 GL1200 Interstate

Re: GL1200 I Poor Power

Postby mainer4 » Tue May 21, 2013 6:14 pm

Hi, yes it was the spring loaded interconnection between the two individual carbs on the right side.
I did read your mentorship of another lister who rebuilt his carbs under your tutelage - very nice of you to help someone so wonderfully! These bikes are far more complex than my simple CB750's and with all the plastic stuff getting in the way, quite daunting to think about tearing into it. I was kinda disappointed about the whole state of affairs as I really wanted to own one of these GL1200's (as opposed to the 1500) but I really knew nothing about them mechanically. I do like the way the bike takes the bumps of our roads in Maine. The CB750's are all much lighter and sprung as sport bikes, so much tougher on my wife's rapidly deteriorating spine.

Visited Randalsomething's site and read all about their rebuild philosophy and kits. Also called around to see how much people get for synching, but I have a 4 guage synch setup already so probably will do it myself. Watched a utube video of someone doing it, had the same setup I do from JC Witless even...

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virgilmobile
Posts: 7663
Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
Previously owned
78 GL1000
81 GL1100
82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: GL1200 I Poor Power

Postby virgilmobile » Wed May 22, 2013 8:59 am

I was a bit overwhelmed too when I got my 1200.
A few weeks later and many hours of undivided attention took care of that.
It's just 1 carb,1 cylinder,1 spark plug times four. :D
When you sync the carbs,continue to keep the RPM around 1000 rpm after each adjustment.
Adjust one carb,adjust the rpm.Over and over.
When completed,each carb will pull the same vacuum at 1000 rpm,then idle it back down to 850.

Run the bike after it's warmed up.It might growl a bit but not rattle and pull smooth to red line.
Keep us up to date.When tuned and proper,it's a rocket.

mainer4
Posts: 8
Joined: Tue May 21, 2013 10:56 am
Location: Limington, Maine
Motorcycle: 1985 GL1200 Interstate

Re: GL1200 I Poor Power

Postby mainer4 » Mon Jul 15, 2013 11:20 am

So for an update, here is what I did
1. Replaced plugs
2. Replaced wires with HONDA OEM
3. Replaced all O rings on the intake manifold and internal on all 4 carbs
4. Set air intake valves to California setting (was set to 49 state setting) since this is a California bike
5. Synced carbs
6. Replaced fuel pump after confirming it was bad (my fault I think).

The bike has more power and is much smoother on acceleration (actually accelerates now). 40MPG on the road with two riders.
All good, but still spits (small misfires) in the 2000 to 2700 rpm range. I am running 91 octane fuel. I am thinking this bike is running too lean but am not very excited about taking everything apart again to try to resolve. Really, what were they thinking?? this is the biggest PITA to work on of all my Honda's - even my 1975 400F is easier!

I have read somewhere that there was a HONDA factory correction for drivability problems for these bikes that included a revised main jet spacer and needle or some such thing. Anyone know if my symptoms are what this is supposed to fix and what a part number might be or what to ask for. Maybe a Fall project....

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virgilmobile
Posts: 7663
Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
Previously owned
78 GL1000
81 GL1100
82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: GL1200 I Poor Power

Postby virgilmobile » Mon Jul 15, 2013 11:30 am

The sputtering.Confirm why before any mods.I could hold 2nd gear at 2500 rpm,add a touch of "choke"and the bike would smooth out.This confirmed a lean condition.I removed the carbs again and added a small washer under the needle to lift it.This took care of the stuttering.

organgrinder
Posts: 5
Joined: Mon May 27, 2013 9:33 am
Location: Olympia, Washington
Motorcycle: 1985 GL1200i Interstate

Re: GL1200 I Poor Power

Postby organgrinder » Tue Jul 23, 2013 8:10 pm

My 1985 1200i stutters a little in second gear and needs a little choke. It was purchased as a high altitude bike before I moved to sea level. When touring and back at 4,000+ elevation (mountain west and beyond) it purrs with no issues. No choke needed at highway speeds at sea level. 48 mpg solo and 43 mpg two up and loaded.

mainer4
Posts: 8
Joined: Tue May 21, 2013 10:56 am
Location: Limington, Maine
Motorcycle: 1985 GL1200 Interstate

Re: GL1200 I Poor Power

Postby mainer4 » Thu Aug 01, 2013 8:06 am

So while getting my 1975 CB750 Supersport inspected at the local Honda dealership I asked about this sputtering issue with the GL1200. The mechanic asked me what I was using for gas and I said 91 octane. Wrong gas he says, you should be using the cheap stuff, it burns faster. Try that and your problem should go away. Haven't filled the tank since as it has been raining so much here in Maine this summer I am not getting much bike time in, so I am not sure if he is all wet or if it will cure it. Sounds a little strange but I will give it a try.

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virgilmobile
Posts: 7663
Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
Previously owned
78 GL1000
81 GL1100
82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: GL1200 I Poor Power

Postby virgilmobile » Thu Aug 01, 2013 10:13 am

The wing was designed to run on 86 octane....use it.
It's some magic formula some geek came up with that has to do with compression ratio/ignition timing/octane rating/torque curve,etc,etc,bla de bla bla bla.... :roll:

mainer4
Posts: 8
Joined: Tue May 21, 2013 10:56 am
Location: Limington, Maine
Motorcycle: 1985 GL1200 Interstate

Re: GL1200 I Poor Power

Postby mainer4 » Thu Aug 01, 2013 10:24 am

hehehe... :D

I am one of those geek types.

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virgilmobile
Posts: 7663
Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
Previously owned
78 GL1000
81 GL1100
82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: GL1200 I Poor Power

Postby virgilmobile » Thu Aug 01, 2013 11:21 am

So you read the owners manual too?
It talks about octane in there somewhere.I just look at the pictures.
Unlike other publications that I get for the great articles. :mrgreen:

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Coolride
Posts: 15
Joined: Mon Jun 10, 2013 9:57 pm
Location: Sebring,FL
Motorcycle: 1984 1200 aspencade

Re: GL1200 I Poor Power

Postby Coolride » Thu Aug 08, 2013 7:09 am

It's more than likely carb related. That bike should give the super sport a good run, at power to weight 7.9 vs super sports 7.3. per horsepower.

mainer4
Posts: 8
Joined: Tue May 21, 2013 10:56 am
Location: Limington, Maine
Motorcycle: 1985 GL1200 Interstate

Re: GL1200 I Poor Power

Postby mainer4 » Thu Aug 08, 2013 8:31 am

I finally rode the bike enough to empty the gas tank and refilled with the mechanic recommended 87 octane. Absolutely no difference in performance. At this point I can only conclude that the bike is running way too lean and Virgil's solution will likely be my solution. No one had come back with the information on Honda's fix for the problem (jet and needle change) so I will try the other forums and Honda dealership. It is surprising to me the previous owner would have run the bike like that for 20 years! With it running this way it does not give me much confidence while riding it. I certainly can't drive it with the choke on! :lol:

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virgilmobile
Posts: 7663
Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
Previously owned
78 GL1000
81 GL1100
82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: GL1200 I Poor Power

Postby virgilmobile » Thu Aug 08, 2013 9:45 am

Before you pop the carbs back on,hook a shop vac to each tube and watch the slides as you operate the throttle.Each one should rise smooth and drop the same with the throttle.Check each one.
Also get the dust caps off and pre-adjust the idle mixture screws.




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