Gearshift sensor and timing advance

Information and questions on GL1200 Goldwings (1984-1987)
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Posts: 2
Joined: Fri Aug 02, 2013 9:16 pm
Location: Pennsylvania
Motorcycle: 1987 GL1200I Interstate

Gearshift sensor and timing advance

Postby Davethemotorhead » Sun Aug 04, 2013 1:13 pm

Hello, I am a forum newbie and found goldwing docs while searching for info for my 87 GL 1200 interstate. The bike had a number of issues when it was purchased last year. And most issues have been resolved and the bike is running mush better. What I am trying to solve now is poor power and acceleration at highway speed (65 and above) and/or climing an incline. I have read that the 1200"s like higher RPM and on your typical 2 lane, if you drop it to 4th it takes off. But if your at highway speed on an incline and roll the throttle it stumbles as if it is not in time. I've come across posts on checking ignition and timing components and have started this process. I checked the gearshift selector sensor by unpluging the sensor wire below the instrument panel and checking continuity through the Sensor plug side Lg/R neutral, R/W 4th gear and G/O overdrive wires. All tested fine which brings me to my questions. 1st on the wiring harness side of the connection what wires carry current? 2nd how does the shift sensor send the electric signal to the ignition contol unit? For reference I have power from the wireing harness plug in the Lg/r (N) and G/O (od) wires. There is no power in theR/W (4th) when the ignition is turne on.
Thanks for any help!!!!

Posts: 55
Joined: Sat May 19, 2012 9:33 am
Location: Port Orchard, Wa and John Day, Oregon
Motorcycle: 1984 GL1200i Interstate

Re: Gearshift sensor and timing advance

Postby BigBro » Mon Aug 05, 2013 9:11 am

Hi Dave, Welcome to the forum.
In reading your post not sure which way you are looking exactly.
Might be a good start to give a little history of what you have done to the ride since you got it.
Some of the things we all get into can also create problems for ourselves on these older rides.

Also having a little history might help one of us point to something you may have overlooked.

There are also downloadable manuals linked on this site and of course others that may also help out.

What you are describing sounds similar to a problem I had with my 1200 except mine would not idle well without choke.
She would pull well when wound up, but was "boggy" when she was down in the 2k-3K range, 5th gear is overdrive and 3k rpms is around 60ish mph. Next time your are out riding try pulling the choke on some see if that changes any symptoms you are experiencing. It really is a fuel ratio enrichment system and that can tell you a lot.

I found numerous problems with it as I worked through my winter maintenance. Most of my issues were related to vacuum leaks (hole in the IAC valve) and failed work(adjustments to correct for other problems) by the PO or their mechanic.

Having the manuals gives you something to reference, having the history of what you have done helps us help you find your problem.

Anyway, stand by I am sure someone more knowledgeable/experienced than myself will be along shortly.

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Posts: 7581
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: Gearshift sensor and timing advance

Postby virgilmobile » Mon Aug 05, 2013 4:30 pm

I've never measured for volts on those wires before but the theory is that the switch grounds a wire as the engine is put in that gear.The ECM module normally supplies some voltage(bias) down the wire and monitors when it goes to ground and responds to that change.
I've heard/read/seen that the ignition timing is altered by 2 possible features....One is the vacuum line and the second is the gear selector position...I think it's in the manual.
I have verified this with a timing light,engine running,in neutral and shorting the wire to ground.I think it's suppose to allow the ignition to advance up near 38* btdc and only 25* or so without the connection made.No visile change at a idle,just above 3000rpm or so.

Posts: 2
Joined: Fri Aug 02, 2013 9:16 pm
Location: Pennsylvania
Motorcycle: 1987 GL1200I Interstate

Re: Gearshift sensor and timing advance

Postby Davethemotorhead » Tue Aug 06, 2013 5:52 pm

Thanks for the welcome and response to my post. I do have a down loaded version of a Haines manual but also found a OEM Honda manual to use as a resource. Virgilmobile - your response confirmed my thought process. My brother-in-law discovered the #2 carburator wasn't getting fuel. We believe the issue was when we took the carbs out to clean & rebuild, the cleaner we used left a film on the float needle which dried and stuck the needle fast. Thus, the bike was only running on three cylinders. Runs great now! Lesson learned: after cleaning & reassembling your carbs, make sure to hook up a short fuel hose & run gas in your carbs to make sure they're working before reinstalling them in the bike! Thanks everyone!

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