GL1200 Won't Idle (Poor Idle)

9161 Views 22 Replies 7 Participants Last post by ctrobins, Apr 9, 2013

ctrobins

Discussion Starter · Apr 6, 2013

Hi,
I just rebuild my carbs (using the Randakk kit) Yay! Even though it looks like two octopuses were in a fight on it with all the vacuum tubes etc. I'm pretty sure all the tentacles ended up in the right places.

I just balanced the carbs also.

I adjusted the Idle mix screws at '3 turns out' from seated.

Here is my situation that I'm hoping to get some advice on:
I set the choke, and the bike starts right up.
BUT, it won't idle if I set the choke completely off. Even when the engine is warm.
so to avoid the engine dying at stops, I reach for the choke as I'm slowing down and open the choke just a little to keep it running.

Should I just adjust the choke to be a 'little open' all the time? Or is there some other thing I could do to fix?

Thanks!
- Craig

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1 - 20 of 23 Posts

77Pinto

· #2 · Apr 6, 2013

ctrobins said:
Hi,
I just rebuild my carbs (using the Randakk kit) Yay! Even though it looks like two octopuses were in a fight on it with all the vacuum tubes etc. I'm pretty sure all the tentacles ended up in the right places.

I just balanced the carbs also.

I adjusted the Idle mix screws at '3 turns out' from seated.

Here is my situation that I'm hoping to get some advice on:
I set the choke, and the bike starts right up.
BUT, it won't idle if I set the choke completely off. Even when the engine is warm.
so to avoid the engine dying at stops, I reach for the choke as I'm slowing down and open the choke just a little to keep it running.

Should I just adjust the choke to be a 'little open' all the time? Or is there some other thing I could do to fix?

Thanks!
- Craig

Not the first to look for someone to tell them that keeping the choke on all the time is a good idea; its not. There is something wrong, so you should fix the problem, not the symptom.

Depending on how dirty the carb.s were, there is a good chance they need to be done again. Getting EVERY bit of crud out the first is not easy, and sometimes crud migrates shortly after the rebuild. I too have had this happen, all seems clean and good, until you run the bike a little. As a matter of fact, I have had carb. sets I needed to tear into 3 or more times.

It could also me that something is not hooked up correctly.

My advice is to take another look with them installed. If you can't find anything on the outside you should look again at the inside.

Bill

trashtruck

· #3 · Apr 6, 2013

pinto is right, it doesnt take much to muck everything up. also, 3 turns out is just a reference or starting point, they still need to be adjusted to the bike. manual describes idle drop down procedure for idle screws.

newday777

· #4 · Apr 6, 2013

What process did you use to clean the carbs?

ctrobins

Discussion Starter · #5 · Apr 6, 2013

Thanks Pinto and Truck! (I think that was the name of a cop show in the 70's

)

I think I'll work on the Idle screws first, and adjust the choke cable properly. I really want to be sure it's needed before I deal with that double-octopus again! (double-octopus = carbs)

- Craig

ctrobins

Discussion Starter · #6 · Apr 6, 2013

To clean the carbs.. I'd call it an overhaul.

I removed the whole 4-carb assembly from the bike.
Disassembled the hoses and all 4 carbs (keeping each set of parts together)
Disassembled each carb, jets, needle valve, Idle screw and meticulously cleaned each piece with Carb cleaner. Sprayed carb cleaner through ALL the ports then blew compressed air through everything. I checked each jet and verified that all the little holes and ports were clear.
I then re-assembled, adjusted the floats to 7mm.
Adjusted the Idle screw to "Seated, then backed out by 3-full turns"
I used all new vacuum and fuel lines.

The carbs did have a lot of gunk in them, and the pins on the needle valves of a couple of the carbs were stuck.. I unstuck them. I would be really surprised if there is some skunge that I missed, after all that.

I used the Randakk rebuild kit with all new gasgets and o-rings.

I'm hopeful it's just the Idle screws that need adjusting!!! The idle problem I described seems only minor, The choke just needs to barely be on for it to run OK.

- Craig

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dizzy

· #7 · Apr 6, 2013

Are you getting idle speed and idle mixture screws mixed up? The mix screws (each carb) you can 'ballpark' at 3 out and you're pretty close. You won't see these unless someone has previously removed the blind plugs or you did. There is no preset for the idle speed and you must adjust your idle to around 900-1000rpm. Maybe you just need to do that. How did you balance your carbs when it doesn't idle?

tprender

· #8 · Apr 6, 2013

The one thing that most people forget to do when rebuilding cards after the bike has set for some time is to change out all of the fuel lines. The old lines will have dried up fuel and dirt in the lines. after some gas has been run though the lines , this dirt will flake off and cloug up the clean holes that you opened up in the cleaning process. Aslo, did you soak the carbs are just spray them with carb cleaner?

dizzy

· #9 · Apr 6, 2013

That may be but if you read the OP's most recent, fuel lines have been replaced.

ctrobins

Discussion Starter · #10 · Apr 6, 2013

I did replace ALL the fuel lines.. from the petcock to the carbs, and new fuel filter.

I did NOT soak the carbs. Just gushed carb cleaner through everything.

Another 'clue' that may help with diagnosis, Is that the bike DID seem to Idle ok at 900-1000 RPM's prior to be rebuilding the carbs... so, I'm hopeful that my cleaning didn't actually introduce 'muck' into the system.

Idle speed screw vs Idle Mix/Pilot screw, I understand the difference. The Idle speed screw is set to idle a little fast (about 1,300 rpm)... I did the carb balancing with it idling this way... I think I had the choke completely off during the balancing, I'll probably need to re-check the balancing.

The Idle Mix (Pilot) screws were all exposed already, and I took them out, inspected cleaned and re-installed replacing the o-rings and washers (from the kit). I did read in the manual about the 'Pilot Screw Adjustment'.

(I appreciate all your input!)

- Craig

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dizzy

· #11 · Apr 6, 2013

Unless the carb synch is massively off you should still be able to get idle at near spec. Adjusting the synch at very fast idle or with enrichener opened will get you less than satisfactory results. I usually think of carb balance as the 'finishing touch' on bike that already runs OK. You may want to redo that eventually. However, from your description it sounds like you may have some residual contamination that has found it's way into your pilot jets/circuit.

You're probably gonna have to reclean the carbs...but here's a 'quick and dirty' you can try. Remove the mix screw, spring, washer and oring from each carb. Drain and remove the drain screw from each carb (both done without removing carbs from bike). Take a good fresh can of carb cleaner, put the tube into each mix screw hole as far as it goes and give it a good flush. Put a rag under the carb to catch the carb cleaner that comes out the drain (sometimes it's hard on the engine paint) Reinstall all parts and give it a try...first start you might want to hold throttle half open as the carb spray will have flooded the intake manifolds. Sometimes this works if the slow circuit contamination isn't really stubborn.

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ctrobins

Discussion Starter · #12 · Apr 6, 2013

Thanks Dizzy! Thats the kind of tip I can live with (jet streaming with the carb cleaner.). Because, I REALLY hope I don't have to take that carb assembly apart again.

I'll try these various suggestions out, and post back the results.

77Pinto

· #13 · Apr 6, 2013

dizzy said:
...but here's a 'quick and dirty' you can try. Remove the mix screw, spring, washer and oring from each carb. Drain and remove the drain screw from each carb (both done without removing carbs from bike). Take a good fresh can of carb cleaner, put the tube into each mix screw hole as far as it goes and give it a good flush. Put a rag under the carb to catch the carb cleaner that comes out the drain (sometimes it's hard on the engine paint) Reinstall all parts and give it a try...first start you might want to hold throttle half open as the carb spray will have flooded the intake manifolds. Sometimes this works if the slow circuit contamination isn't really stubborn.

Yes, you can try what he says, but if you used compressed air on those before and they were clean before you installed them as you said, then if they are still clean they are not the issue now and you need to pull them apart again. If they are now clogged (or just one) you need to un-clog, and even if you can do that with the carb.s still in the bike (and not damage/loose any of those small parts, or ruin your paint), the stuff doing the clogging came from somehere, and EVERYTHING needs to get checked again (pull them out/apart).

dizzy said:
.....You're probably gonna have to reclean the carbs.......

I agree 110%, reguardless of wether or not he does what you posted.

ctrobins said:
Thanks Dizzy! Thats the kind of tip I can live with (jet streaming with the carb cleaner.). Because, I REALLY hope I don't have to take that carb assembly apart again.

I'll try these various suggestions out, and post back the results.

Shortcuts can and will leave you stranded, and maybe have you doing far more work in the long run. Also, you might be amazed on what you find if you go back into them; I know I have.

Bill

dizzy

· #14 · Apr 6, 2013

If the slows were clean before and some miniscule bit has become lightly lodged this procedure might clear it and flush the float chambers. I've done this many times and sometimes it works, sometimes it doesn't. I usually figure it's worth a try.

ctrobins

Discussion Starter · #15 · Apr 6, 2013

I tried the 'back flushing' that Dizzy suggested. I did it on just 2 cylinders... the right side (which is where I suspect the issue was coming from.) I THINK IT WORKED!

The bike WILL Idle now without the choke... but, the idling is very rough. I will try to balance the carbs again and see where it leaves me.

tire joe

· #16 · Apr 7, 2013

CT is the fuel tank clean?

ctrobins

Discussion Starter · #17 · Apr 7, 2013

Ugh... I don't know if the fuel tank is clean! I did put a new fuel filter... But, I know the bike had been sitting for some time (maybe over a year) prior to me getting it 2 weeks ago, so I bet there could be some filth in the tank as well. I'll check that out!

Thanks for the suggestions!

newday777

· #18 · Apr 7, 2013

Best way to check /inspect the tank is remove the fuel level sender from the tank. Must be below 1/2 tank level or better yet empty.

77Pinto

· #19 · Apr 7, 2013

ctrobins said:
I tried the 'back flushing' that Dizzy suggested. I did it on just 2 cylinders... the right side (which is where I suspect the issue was coming from.) I THINK IT WORKED!

The bike WILL Idle now without the choke... but, the idling is very rough. I will try to balance the carbs again and see where it leaves me.

I stand by my statements in post 13.

If the carb.s were clean when you put them back in, and 're-cleaning' just part two of the carb.s has now made the bike run better indicates that there was more crud in them that had to come from somewhere. The likelyhood of even more crud hiding in the carb.s is very high, so my question is: Would you rather deal with it now, or would your rather take a risk and have it re-crud when you are 100 miles from home?

Bill

ctrobins

Discussion Starter · #20 · Apr 7, 2013

UPDATE:
I looked down the filler neck of the gas tank. It looks like there are spots of rust, or some other form of contamination lining the inside walls. There may still be some 'old' gas in there too. When I bought the bike it had about 2 gallons of fuel in it (I don't know if it was new or old gas), and I filled up before I drove it home.. so maybe it's 50/50 bad gas.

1 - 20 of 23 Posts

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