Low Fuel Mileage????

Information and questions on GL1200 Goldwings (1984-1987)
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Posts: 8
Joined: Sat Oct 08, 2011 10:20 am
Location: Bellevue, NE
Motorcycle: 1984 GL1200A Aspencade
1977 GL1000
1986 Suzuki GS550L

Low Fuel Mileage????

Post by DRDIESEL77 » Fri Oct 31, 2014 4:23 am

I have a 84 Aspy and i am getting terrible mileage. I am averaging 18-22 mpg and the bike smokes raw gas out the exhaust. I had starting issues where the bike wouldnt start, but that is fixed, (timing belts were stretched and engine was not in time). I had a local shop look at the bike and they found the timing issue. they got the bike running but said it ran rough and they said that they adjusted the carbs to get the bike to run better. That was the end of last November and i didnt have a chance to ride it after i picked it up. This year when i started the bike up and was riding it, it was backfiring really bad. I found that 2 and 3 spark plug wires were backwards on the coils. Swaped the wires and the bike runs great except for the poor mileage. i did have the carbs cleaned and rebuilt before i started having the starting/running issues. The shop i took it to and got it running said that i needed the carbs rebuilt again and that I had a broken pilot screw on #1 cylinder. The shop owner retired and moved to a warmer climate and I have no way to ask them what they adjusted. Is it possible that they adjusted the sync on the carbs to compensate for the 2 wrong plug wires and or what other adjustments could they have done??? I havent had a chance to check the carb sync because I need to get a gauge set. i was planning on rebuilding the carbs again this winter but if it is something as simple as resync the carbs could that take care of the mileage??? Aslo when i fire up the bike it smokes terriblely and really heavy fuel. it will almost burn the eyes if i start it in my garage even with the doors open. Any advice would be great. Thanks

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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: Low Fuel Mileage????

Post by virgilmobile » Fri Oct 31, 2014 7:35 am

I guess I'm most interested in the "broken pilot screw" part...
if the tip was broken off and the threaded part of the pilot screw simply put back in the carb..that one carb will run very rich..
Add to that an attempt to adjust the carbs with one having a known problem and 2 cylinders not firing is just putting a band aid on it to get the bike out of the shop...(Yup...we got it runnin..) Sheesh.

The sync is most likely out of whack....There is a way to get them close without gauges...It's simply getting all 4 throttle valves to close and open at the same time....Not very accurate but enough to get by with.
For me,my first look would be with a small screwdriver and gently removing each idle screw while the carbs are on the bike...one at a time...inspect them...good ones are turned back in till they seat(just snug) then backed out around 3 to 4 turns..
this is a starting point....
Then fiddling with the throttle screws to see how they actually operate each carb(open/closed).
The carbs must be synced before the "fine tuning" idle down pilot screw is adjusted again.

Or just pull them and take a day and go over them yourself..bench test and adjust before you put them back on.
By the way..My 84 interstate ran 30-40 mpg and I did a few mods to the carb too.

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Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (wife's!)
1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer

Re: Low Fuel Mileage????

Post by WingAdmin » Fri Oct 31, 2014 11:39 am

Might want to check the compression to rule out valve damage from the timing issues.

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