84 gl1200 carb problem?


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virgilmobile
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84 gl1200 carb problem?

Post by virgilmobile » Mon Nov 14, 2011 1:27 pm



Sounds like it's lean,stumbling from 2000-3000 rpm.Add a little "choke" or fuel enrichening and it smooths out.
Popped the carbs off and gutted them.Checked the float level,inspected all the jets,ports,air passages,air valves,etc,etc.Everything is spot on and clean.No contamination.
I can't find any reason for the lack of fuel in that rpm range.Even the enrichening valve is ported from the idle jet as are the 4 midrange holes.So it's not a idle jet problem.
Some reading mentioned adding a spacer under the main jet needle,other increase the jet size,and some say a pulse coil gap problem.
This idles great and pulls smooth from 1000-1800 then again from 3000 up.
When at 2500 rpm,it sounds and feels like a twin.Add a little choke and it sounds and feels like it's firing on all 4.(not a ignition problem)?.
I checked the cutoff valve and the reed valves(working,no leaks).All the hoses are clean and pliable.
Original hoses however.
I'm stumped on this one.
I can't point my nobby finger at a single defect.
Help??? :)



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tricky
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Re: 84 gl1200 carb problem?

Post by tricky » Tue Nov 15, 2011 9:50 am

how about checking the fuel pump and or filter, especially the filter.
unless of course you already have.
I know some of the fuel filters have been breaking down recently

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virgilmobile
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Re: 84 gl1200 carb problem?

Post by virgilmobile » Tue Nov 15, 2011 11:42 am

Been there,fixed all that(even the noisy ticking pump).The bike pulls fine above 3000 rpm,so not a fuel flow problem.
I've been reading that the 84 had a factory mod for this problem.
I'm researching adding a 3mm shim to lift the needle up and changing from a #35 pilot jet to a # 36. :?:

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virgilmobile
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Re: 84 gl1200 carb problem?

Post by virgilmobile » Tue Nov 15, 2011 4:10 pm

Here's the most common info across the board about the 1200 carb problem.
I got the stuff to try it....http://www.goldwingfacts.com/forums/forum1/50239-1.html.

I'll know in a day or so and I'll post my pix of the work.

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virgilmobile
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Re: 84 gl1200 carb problem?

Post by virgilmobile » Wed Nov 16, 2011 3:12 pm

Update so far,mosquitoes are eating me alive,and I found some problems in the carbs.
2 pilot jets near plugged
1 spring on a needle valve seized
Out of 4 idle mixture screws,not any one were set the same,eg.1and1/2 to 3 and1/4 turns out.
All the slides were scuffed up and MAY have been dragging.
Other than replacing the pilot "O" rings,the only mod is I added a shim under the main needle metering rod.
Here's the pix.
Hope to finish tonight and sync tomorrow.Gonna be 78 this weekend :)
scuffed slide bore
scuffed slide bore
Attachments
cleaned all the pilot jets
cleaned all the pilot jets
farm fresh slides
farm fresh slides
polished the slides with 2000 grit
polished the slides with 2000 grit
added a shim to let in more gas
added a shim to let in more gas
drilled the pilot cap
drilled the pilot cap
heat needed to remove the cap
heat needed to remove the cap
popped right off
popped right off
polished the bore with 2000 grit
polished the bore with 2000 grit

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seabee_
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Re: 84 gl1200 carb problem?

Post by seabee_ » Thu Nov 17, 2011 10:09 pm

I was going to suggest the mixture adjustments but I see you already found that. I was also going to recommend synching the carbs. I had a KZ400 that had the same symptoms and rebuilt the carbs thinking that would fix it. In the end found the idle mixture screws way out on adjustment and carbs way out of synch even after bench synching with feeler guages. Built a homemade manometer and synched the carbs. Man, what a difference that made.
By the way, nice pics on the progress.
Paul
CE1 Navy Seabees/RET
1981 to 2002
ASE Mechanic

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virgilmobile
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Re: 84 gl1200 carb problem?

Post by virgilmobile » Fri Nov 18, 2011 9:18 am

Thanks for the info.Here's the final results...
Note:prior to repairs,,at 2500 rpm in the shop,if I add a little "choke"the rpm would climb to just over 3000 rpm.Now if I add a little choke the rpm drops.This indicates the fuel mix is about right.
1.found 2 idle jets near plugged.I could see through them,but only barely.
2.the slide bore and slides were scuffed,not really bad,so I polished them anyways.After I put them back,I used a vacuum cleaner hose to watch the movement of each one,simulating the engine demand and slide response.
3.I found the idle screws were set from 1/2 to 3 turns out.I replaced the "O" rings and set them to 3-1/2
4.I added a 0.033 washer under the main needle to lift it and hopefully get a little more overall fuel delivery.Just trying to get rid of the lean condition.
5.I replaced all the rubber hoses and "O" rings on the down tubes.
6.Mechanically set the throttle and re-assembled the bike.
7.Synced the carbs at 700 rpm.
8.Adjusted the idle jets at 900 rpm > I turned them IN till I saw and heard a idle drop and then turned them 1 full turn back out.Each one ended up being 4 turns from the bottom.
9.Re-synced the carbs again to the nats ass.

I held the throttle at 2000 rpm and applied a little choke and the rpm dropped.Just what I'm looking for :D
It was 37 degrees when I finished,so a test run this weekend,79 degrees. :)
The throttle response is much snappier and I have a hard time trying to hold it at 2500 rpm.It just seems to go from a idle to 5 grand with just a little tweak on the throttle. :o




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Re: 84 gl1200 carb problem?

Post by new82 » Thu Dec 01, 2011 8:45 pm

virgilmobile wrote:Update so far,mosquitoes are eating me alive,and I found some problems in the carbs.
2 pilot jets near plugged
1 spring on a needle valve seized
Out of 4 idle mixture screws,not any one were set the same,eg.1and1/2 to 3 and1/4 turns out.
All the slides were scuffed up and MAY have been dragging.
Other than replacing the pilot "O" rings,the only mod is I added a shim under the main needle metering rod.
Here's the pix.
Hope to finish tonight and sync tomorrow.Gonna be 78 this weekend :)
Hi Virgil - Are you really 78?? you looked a LOT younger when I met you. congrats on a life well lived.

I'm still playing with getting my carbs syncéd (still rough from idle to about 2200, & lots of primary chain rattle) but i was wonderring if the 1200 needle shims would help the 1100. seems to me the ethanol problem would be same for 1100s & even 1000s

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virgilmobile
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Re: 84 gl1200 carb problem?

Post by virgilmobile » Thu Dec 01, 2011 10:40 pm

Well sometimes I FEEL 78,but I'm not quite there yet.I do qualify for the senior discount at Goodwill tho.
I really don't think that lifting the needles in the 1100 or 1000 may help much.After I polisheed the carbs in the 1100 really,really good and adjusted the snot out of them the bike will pull off at a idle(900 rpm) ,Idle down the road and twist the throttle half way and it just pulls smooth through 7 grand.
Lifting the needle .033" on the 1200 provided just a bit more fuel to help with a little lean condition.I really think the sticking slides and mis-adjusted idle screws had a big part in it.That is what cleared up the 2000-3000 rpm lag problem.

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Re: 84 gl1200 carb problem?

Post by Hawkengl1000 » Thu Apr 13, 2017 6:25 am

I know this is a very old post but does any one know what the diameter of the shim I'll need.

Thank you

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virgilmobile
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Re: 84 gl1200 carb problem?

Post by virgilmobile » Thu Apr 13, 2017 10:13 am

Not a clue. I pulled a needle and went to home depot.Found a small box of very small flat washers.Nothing special ordered.The measurement of thickness was after I smoothed it on a bit of 1500 grit paper.
The hole was probably metric..Maybe 2mm or around 1/8".Outside about 3/16" If its tight,it can be reamed out or trimmed down.
Its only purpose is to lift the needle a bit higher to increase the fuel mix in the power range.
Even a hobby shop should have an assortment of flat washers.

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Re: 84 gl1200 carb problem?

Post by Hawkengl1000 » Thu Apr 13, 2017 10:19 am

Thank you for your reply. I did the same I bought a box of multiple sizes. Put two in as they were very thin an looked around .03 but engine is lagging so I'll remove one when I get home again and try it again.

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virgilmobile
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Re: 84 gl1200 carb problem?

Post by virgilmobile » Thu Apr 13, 2017 12:33 pm

Can you add a bit of choke and eliminate the lag?

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Re: 84 gl1200 carb problem?

Post by Hawkengl1000 » Thu Apr 13, 2017 12:35 pm

Yes if I pull the choke it's fine

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virgilmobile
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Re: 84 gl1200 carb problem?

Post by virgilmobile » Thu Apr 13, 2017 12:45 pm

OK.Ill pole around and get back asap

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virgilmobile
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Re: 84 gl1200 carb problem?

Post by virgilmobile » Thu Apr 13, 2017 12:51 pm

Did adding the washers help at all?

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Re: 84 gl1200 carb problem?

Post by Hawkengl1000 » Thu Apr 13, 2017 12:54 pm

Before it was carb popping. Now it's lagging so I just take it's got too much fuel now

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Re: 84 gl1200 carb problem?

Post by Hawkengl1000 » Thu Apr 13, 2017 12:59 pm

It's ok I'll take one out when I can and I'll let you know how I get on.

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Re: 84 gl1200 carb problem?

Post by virgilmobile » Thu Apr 13, 2017 1:09 pm

No.Don't remove the washers.Popping is lean.lifting the needle helped..now lagging..add more fuel(choke) clears it up.
Its still lean.
Did you add the washer to all 4 needles?

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Re: 84 gl1200 carb problem?

Post by Hawkengl1000 » Thu Apr 13, 2017 1:12 pm

Yes I added them to all of them. Should I add another one

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Re: 84 gl1200 carb problem?

Post by virgilmobile » Thu Apr 13, 2017 2:15 pm

No.We may be going down the wrong rabbit hole.
Go back to the original problem.Popping in the carb.Did you solve this before adding the washers?

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Re: 84 gl1200 carb problem?

Post by Hawkengl1000 » Thu Apr 13, 2017 2:16 pm

No I hadn't. As I understand it the popping in the carbs is caused by it running too lean. Then I've come across multiple post saying about adding a shim.

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Re: 84 gl1200 carb problem?

Post by Hawkengl1000 » Thu Apr 13, 2017 2:26 pm

Basically bike had been sat for 8 years I've put new breaker points on. Gone through the electrics. Stripped the carbs. It's had been synced before I stripped them for the second time. I have 180 psi on compression test on each cylinder. I've put a new kit in the air cut off valve. So that's what brought me to the shim. I should have said mine is 78 gl1000

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Re: 84 gl1200 carb problem?

Post by virgilmobile » Thu Apr 13, 2017 2:41 pm

Does this bike have points and are they set by the "split the difference method" Adding the washers helped but didn't cure the original problem.It just masked it.Yes it does fix a lean midrange condition but you started with a overall very lean condition.
Back away from the washers as a fix.It won't work.
Popping in the carbs...first.
I'll list stuff to do first.
Leave the washers in there.
This is gonna take a while.
Disassemble each carb one at a time.Polish the slide bore and slides with 1500 or 2000 grit paper.
Clean each jet by hand.Readjust each idle jet to the factory specs.
Measure the float height exactly..just resting on the pin.
After there done, use a shop vac and operate the throttle.verify each slide operates exactly the same.Mechanically sync the throttle plates,verify the quality of the carb mount "O" rings.Mount the carb and secure the rubber coupler clamps(I forgot that once).Vacuum sync the carbs as close as possible at 1000 RPM.
Any one of these steps missed can cause a lean condition.

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Re: 84 gl1200 carb problem?

Post by Hawkengl1000 » Thu Apr 13, 2017 3:46 pm

The carb popping only happens in low revs after 3000 it's beautiful. Everything I've read just pointed at the shim.

I haven't polished the slide bores or synced the carbs since I've cleaned the carbs.
The o-rings are new on the carb manifolds, floats were measured to around 22mm but not sure what you mean by resting on the pin. I'm sure in manual it says 22mm.

You say readjust the idle jet as in 2 1/2 turns out?
I used carb syncing kit before but don't know what you mean by mechanical sync.



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