'85 GL1200i Single Cylinder Misfiring


Information and questions on GL1200 Goldwings (1984-1987)
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jtprouty
Posts: 8
Joined: Sat Jul 13, 2013 1:50 pm
Location: Wichita, Kansas
Motorcycle: 1985 GL1200I Interstate

'85 GL1200i Single Cylinder Misfiring

Postby jtprouty » Tue Apr 28, 2015 7:36 pm



Hi All,

My GL1200i sat for 6 months while I waited for warmer weather and the opportunity to change the camshaft seals and timing belts. Got it back from the shop after the repairs and now one of the left cylinders is running rough/intermittent. The garage cleaned the carbs and suggested that I run some fuel system cleaner through it and run it for around 100 miles to see if that helps. I only have about 40 miles on it but I'm not seeing much improvement. Any suggestions? It has over 156k miles on it and I don't know when the plugs were last changed.

Thanks,

Jimmy



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virgilmobile
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Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
Previously owned
78 GL1000
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84 GL 1200 I

Re: '85 GL1200i Single Cylinder Misfiring

Postby virgilmobile » Wed Apr 29, 2015 11:33 am

If the "garage" cleaned the carbs,there's little use in running Sea Foam.
Start from scratch.Spark,compression and fuel.Which one is wrong.
Start with the easy stuff...swap plugs.test.Check spark on the same side..both front and rear for similarity.
Compression test...
If all that turns out OK,pop the carbs off and go over them.
Or take it back to the repair shop and let them figure out what happened.
Maybe a tooth or two off on that timing belt?Plugged idle jet?carbs not synced?
Bad spark plug.?

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virgilmobile
Posts: 7650
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: '85 GL1200i Single Cylinder Misfiring

Postby virgilmobile » Wed Apr 29, 2015 11:37 am

I identify which cylinder is having a problem by starting the engine from dead cold...keeping the rpm near a idle,not revving it up at all...let it idle for 8 seconds or so then shut it down.Lightly tap each exhaust header pipe.The one that's cold is your problem cylinder(s).
And yes I've seen the wing idle on just one cylinder too.

jtprouty
Posts: 8
Joined: Sat Jul 13, 2013 1:50 pm
Location: Wichita, Kansas
Motorcycle: 1985 GL1200I Interstate

Re: '85 GL1200i Single Cylinder Misfiring

Postby jtprouty » Wed Apr 29, 2015 12:27 pm

Thanks, guys.

It seems to run better at higher RPM and cuts in and out at lower RPM. I'm a bit leery about taking the carbs apart for fear of changing something that will cost big bucks at the garage to get fixed. I'm an aircraft mechanic but work jets (don't have carbs) - carbs scare me. :shock: I'll figure out which one's not running properly and then try changing the plugs.

They did change the timing belts but wouldn't that be a problem on all 4 cylinders if it was off?

Thanks again,

Jimmy

User avatar
virgilmobile
Posts: 7650
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: '85 GL1200i Single Cylinder Misfiring

Postby virgilmobile » Wed Apr 29, 2015 1:15 pm

If one timing belt were off its mark,it certainly can affect just that one side of the engine and seemingly one cylinder more that the one next to it.
Carbs are generally robust simple mechanisms.Theres just a bunch of parts times four.
"Cutting in and out"is the problem for me.process of elimination first.Spark,compression then fuel.One step at a time.
Even a weak spark from a poor coil can show up on just one cylinder.
Look at the plugs as you remove them.There condition tells much about how that cylinder is firing.Find the one that isn't like the rest.

jtprouty
Posts: 8
Joined: Sat Jul 13, 2013 1:50 pm
Location: Wichita, Kansas
Motorcycle: 1985 GL1200I Interstate

Re: '85 GL1200i Single Cylinder Misfiring

Postby jtprouty » Wed Apr 29, 2015 2:25 pm

Thanks again! Spark was going to be my starting point a d your advice confirms my choice. I'll dig into it and post what I find.

Thanks again,

Jimmy

User avatar
virgilmobile
Posts: 7650
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: '85 GL1200i Single Cylinder Misfiring

Postby virgilmobile » Wed Apr 29, 2015 3:06 pm

Ya might have a read through this saga ....viewtopic.php?f=5&t=26826

jtprouty
Posts: 8
Joined: Sat Jul 13, 2013 1:50 pm
Location: Wichita, Kansas
Motorcycle: 1985 GL1200I Interstate

Re: '85 GL1200i Single Cylinder Misfiring

Postby jtprouty » Wed Apr 29, 2015 6:07 pm

Wow, great read! Thanks.

jtprouty
Posts: 8
Joined: Sat Jul 13, 2013 1:50 pm
Location: Wichita, Kansas
Motorcycle: 1985 GL1200I Interstate

Re: '85 GL1200i Single Cylinder Misfiring

Postby jtprouty » Sun May 03, 2015 11:01 am

Finally over my cold well enough to do some troubleshooting. Was planning on testing the spark plugs today and, since I don't have any history on the old ones, I stopped and bought some new to install after testing the system. The first plug I pulled didn't look very bright so I installed a new on and tested it - she purrs like a kitten! It was either a bad plug or the cap wasn't installed correctly. I also found that the plugs didn't seemed to have been seated properly either. Both came out without having to put my socket wrench on the socket.

Took her for a quick run around the block and she didn't miss a beat, even without letting her warm up. Got lucky on this one! $1.88 for a plug and I'm back up and running again.

Thanks again for your help! Really appreciate everyone's advice.

Jimmy




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