misfires both up and down


Information and questions on GL1200 Goldwings (1984-1987)
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MNAspencade
Posts: 22
Joined: Wed Aug 21, 2013 7:02 pm
Location: Jacobson, Minnesota
Motorcycle: 1985 Gl1200 Aspencade

misfires both up and down

Postby MNAspencade » Wed Feb 26, 2014 6:31 pm



I recently aquired an 85 aspencade. after a bit of battery fuse work got her running - barely. It popped up through the intake and took a fair amount of choke to get it going. Before the snow flew I had the carbs off and cleaned them. But at the time I did not know about the hidden pilot screws. Planning on taking them off again and cleaning them up. Does anyone have a source for just the washers and o-rings for the pilot jets? While I had the engine running I put a inductive timing light on each plug wire and noticed that the rear cylinders were flashing at a much faster pace and more erratic than the fronts (seemed normal). Once the weather gets above freezing ( and zero ) new plugs, wires, and boots will be going on as a matter of routine maintainence (not sure what all the PO did). Also while it was running I noticed it would backfire sometimes through the intake plennum ( right rear ) and occasionally through the exhaust. One question I have for the electrical gurus is what would cause the erratic pulses on the rear plugs? could it be a pulse generator issue, an ECU issue, or just nasty carbs, and would this cause thetwo side backfire issues? I would prefer not to just throw parts at the issue without sound advice.

Thanks
Ride safe



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virgilmobile
Posts: 7647
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: misfires both up and down

Postby virgilmobile » Thu Feb 27, 2014 9:46 am

MNAspencade wrote: erratic pulses on the rear plugs? could it be a pulse generator issue, an ECU issue, or just nasty carbs, and would this cause the two side backfire issues?


Usually backfiring just in the carbs is a "lean" fuel condition..
Backfiring in the exhaust is a "rich" condition...
Seldom do they both exist....
Given the unknown history,I'd be inclined to test everything...
First...verify compression....The numbers are not as important as how close they are to each other.
The ideal range is at least 135 psi with less than 5 psi difference.

The erratic spark...Hmmm...The 1200 uses 2 pulse coils,one ignition module and 2 ignition coils....
A 4 wire plug to the left of the battery contains the pulse coil wires...2 for each coil..
This plug,as well as the 3 yellow wire stator plug, are always subject to corrosion....inspect and repair as needed..
I just bumped mine and killed the ignition..there's just a tiny voltage on these wires so any corrosion is bad.
Look for corrosion at the ignition module plug also...(while your there,inspect the rectifier/regulator connections too)
***Good battery voltage is a MUST...Any electronics do not work well with low voltage....
On the bike,for good spark,you really need to have at least 12.5 volts at the battery contacts while running the engine....If it drops below 10.5 volts,the ignition gets "iffy"....
***Measure the battery volts at 1500 rpm....expect no less than 13.2 volts...And should never exceed 14.5 volts at 3500 rpm....
The last is the ignition wires from the coil....Go "buy the book" resistance measurements of the caps,wires and coil....Easy first test...Ohm measure between the front 2 plug caps...then the rears..
A poorly running 1200 is usually associated with carbs...Mine was the worse case...one cylinder dead,backfire in the carbs,won't idle smooth.etc etc.
A detailed cleaning,pre-alignment of the carbs,then a good sync at 1000 rpm fixed it good.viewtopic.php?f=5&t=9179
A lot of electrical problems associated with the charging system were resolved too...viewtopic.php?f=5&t=12522

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MNAspencade
Posts: 22
Joined: Wed Aug 21, 2013 7:02 pm
Location: Jacobson, Minnesota
Motorcycle: 1985 Gl1200 Aspencade

Re: misfires both up and down

Postby MNAspencade » Sun Mar 02, 2014 10:38 pm

Thanks for the reply. My first crack at getting some work done ( after the temps start to move into the positive numbers) will be getting the pilots checked out, floats set to a gnats arse, and a synch if I can get it running well enough. I am figuring I will nee/want to replace the o-rings and likely the small washer with the pilot cleaning. does anyone know of a source for just these parts short of buying a whole carb kit?

As it warms up I will let you know how it goes.

Ride safe!

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MNAspencade
Posts: 22
Joined: Wed Aug 21, 2013 7:02 pm
Location: Jacobson, Minnesota
Motorcycle: 1985 Gl1200 Aspencade

Re: misfires both up and down

Postby MNAspencade » Wed Mar 12, 2014 3:20 pm

With temps up into the 20's I finally got the carbs off and the pilot screw plugs out. only one carb had the screw at 2 1/2 turns out, the other three were only 1/8th to 1/4 turns out. I do not know how these needle screws could work their way IN - especially with the spring giving tension?? The passages were all clear. the o-rings were as flat or flatter than the metal ones ;) . Trying to locate some o-rings and going to get the shims and do the main needle mod before buttoning it back up.

User avatar
virgilmobile
Posts: 7647
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: misfires both up and down

Postby virgilmobile » Wed Mar 12, 2014 9:06 pm

Pre-test and adjust the carbs before you put them back on.I use a shop back to see the slides work.A mechanical adjustment of the throttle plates helps for a pre-sync setting. Adjust all 4 idle mix nets at 2 and 1/2 turns from bottom.It's a reasonable starting point.
Fill the carbs with gas and check for bowl leaks.

User avatar
MNAspencade
Posts: 22
Joined: Wed Aug 21, 2013 7:02 pm
Location: Jacobson, Minnesota
Motorcycle: 1985 Gl1200 Aspencade

Re: misfires both up and down

Postby MNAspencade » Thu Mar 13, 2014 6:24 pm

I am going to try the shop vac test of the slides before installing them again! think I will fit new timing belts and clean up around the pulse coils before I get too far along. Now to dig up that Gates part number for those belts.

Thanks for the help !

Ride safe




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