Fresh Carb Cleaning, Tune but Still

1242 Views 14 Replies 8 Participants Last post by tjradphilly, Oct 14, 2009

tjradphilly

Discussion Starter · Oct 11, 2009

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Ok, I cleaned the carbs, checked the vaume lines, hooked up the Mamo and tuned her. She's running real strong except one issue that seems to be cropping up. When at lower idle speeds or down throttling around 2k I get a cough back through the 2 and 4 carbs. 1 and 3 seem to have no problems....

I pulled the carbs again, checked all my seals and re cleaned my jets. check plugs they were clean and re-gapped at 28.

The bike is older 84 GL1200and was not cared for properly. The tune was way out when I first fired her up before doing my work.

At speed, on excel and on the highway not a problem. An occational cough at idle.

I'm not sure where to look or if this is characteristic of the older opposing motors. I remember having an inconsistent idle on my R60 BMW and was told by two dealer mechs that it wasn't out of the ordinary and the bike was running fine.

Should I be looking at anything else?

Does anyone else have or had the same issue?

Otherthen this issue she's running like a champ.

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fgh

· #2 · Oct 11, 2009

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Check your coils. You'll have to pull the false cover. The plug on an 83 is on the left behing the steering stem. There will be three wires, probably blue, yellow and black. Open the connector and clean the plug on the loom side with CDC or some electric cleaner. Pull the coils and clean all connection on them including the spark plugs. Check the primary and secondary coil resistances and replace any coil that is out of spec. Check the resistance on the plug wire and cap. It should be 5K +/- 10%. Hope this helps. LOL!!!

tjradphilly

Discussion Starter · #3 · Oct 11, 2009

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Thanks, I will check that out ASAP.

DaveO430

· #4 · Oct 11, 2009

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It is probably still a little lean on those 2 cylinders at least. I would turn the mixture screws out 1/2 turn each and see what happens. Ignition problems tend to show up under load.

tjradphilly

Discussion Starter · #5 · Oct 12, 2009

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That sounds good. Because under load the bike is running it's best.There are no other signs of ignition problems. Plugs are clean engine is smooth even through the coughs it catches right back up.Under loadit's pulling the mixture harder and I have no problems. I'll move them a 1/4 at a time and see what I get while riding to work in the morning.

I wanted to make sure I'm on the right track with this unfamiliar motor.This is my first wing and I wanted to make sure I wasn't trying to fix a characteristic of the bike since it's running so strong at speed and really this is only the occational cough.

Thanks again.

tjradphilly

Discussion Starter · #6 · Oct 13, 2009

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Ok got it figured out, there was a combination of issues. First, did the small on road adjustments and nothing.

So when I got home I checked out the ignition system all checked good. Then I hooked up the mamo and got ready to check it. Started fine then drew down slowly to a stall and wouldn't restart. Needless to say this was confusing because I assumed that I over adjusted. However, after backing off to the previous settings still nothing.

Talk about scratching your head. I continued to back off the adjustments and still nothing. Just cranked over with no spark. So I grabbed the started fluid just to give it a shot and see if I had spark and what do you know. Fires up and stalls. Hummm.

So I packed it in for the night to think about it. Today when I got home I decided to check the fuel pump first on a long shot. low and behold no pressure. I had a spare pump so I put it in and still nothing. No fuel flow. So I pulled the Fuel Pump relay plug and bypassed it and the pump came on.The bikestartedthen faded off and stalled.I pulled the relay its self out and the back had literally blown loose and smelled like burnt plastic.

Off to the local scrap yard. $20 for a new/used one. I put it in and bingo she's back running. I think my old fuel pump went or the relay popped either way I'm leaving the newer fuel pump in. Ok one problem solved tuned her up gain and still coughing. Ok now I'm frustrated, I thought that the bad relay may have cause some inconsistent pressure in the fuel lines giving me the heartburn in the first place. NOOOOO can't be that easy

.

Ok the only vacuum I hadn't checked was the intakes. So I fired her up and used a little starter fluid around the base of the carb intakes to check the seals forleaksand the engine ran up on two of the cylinders. I have two bad O-rings. Simple is usually the hardest to find. This would also account for the inconsistency in the coughing.

At least the fuel pump relay went now and not on the road. :clapper:

I'll pick up some new O-rings this weekend and I should be good. Wheew.

:cheeky1::cheeky1::cheeky1::cheeky1::cheeky1::action::action::action::action:

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CaptainMidnight85

· #7 · Oct 14, 2009

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That's a lean-out condition alright.
Now if I can fit just one more card into my gray-matter file.... :cheeky1:
Murphy-Simple is what I like to call it.

Edit: good job chasing it down.:clapper:

Armo

· #8 · Oct 14, 2009

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here is EXACTLY what's wrong, (in my humble experience).
Each Carb has a Pilot Screw, this is covered by a plug, this plug must be drilled out and remove first, not hard and doesn;t have to be replaced.
But before unscrewing out the pilot screw, FIRST screw it in and write down the number of turns it takes to turn it in, each carb may be different, then you can remove the pilot screw, and clean it out, it takes a VERY thin wire to pass it through the hole, if you can't pass a wire through it, then apply heat from a torch, then you would be able to pass a wire through it.

Armo

· #9 · Oct 14, 2009

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okay, I didn't read ALL the posts, so sue me!

tjradphilly

Discussion Starter · #10 · Oct 14, 2009

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:cheeky1:

Not the suing type but the pilot screws were on my list if all else failed. I don't like digging into them unless I absolutely have to. I have found that in most cases you can fix it with outremovingthe pilots. I have had to do it before just not preferred by me.

escogold

· #11 · Oct 14, 2009

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went thru the carbs on one of my 12's and she's running great except still have a noticeable bog under load off idle up to around 15 to 1,800 rpm. still haven't figured it out yet but this topic has given me some fresh ideas. i'll stay with it and post when i get it solved. thanks y'all.

Redeye1620

· #12 · Oct 14, 2009

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A question from a newbie, What is a Mamo? Thanks.....-Rich

satan

· #13 · Oct 14, 2009

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Could be just me, but I've read it ("Mamo") as a misnomer for 'manometer' (a cluster of vacuum gauges in this case for carb-balancing; likely liquid-filled)

CaptainMidnight85

· #14 · Oct 14, 2009

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Manometer... it's a set of guages (1,2 or 4 usually - sometimes called vacuum guages byus biking crowd) used to synchronize, or balance equally the air intake of your carburetors. Measures the air volume in pressure under vacuum from the carburetors to the combustion chambers via the individual intakes. One carburetor is set to factory specification, and the rest are balanced to that one. Some further the process by balancing the left and right banks additionally. Different manometer fluids within each given set of manometers give different levels of accuracy as we're measuring vacuumagainst the specific gravity of the involved fluid. Mercury, light oils and water are some of the fluids used. Some of us make our own set of guages for a number of reasons. This is simplified of course, but try drawing water out of a cup through a straw, and then try drawinga milkshakethrough the same straw,... it takes longer.

Edit: Didn't mean to post over top of you satan. This time of day I'll start a response that I may not get posted immediately, sometimes over- lapping others.

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tjradphilly

Discussion Starter · #15 · Oct 14, 2009

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satan wrote:

Could be just me, but I've read it ("Mamo") as a misnomer for 'manometer' (a cluster of vacuum gauges in this case for carb-balancing; likely liquid-filled)

Couldn't have said it better myself.

Mine are Mercury filled.

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