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Discussion Starter · #1 ·
I used the search bar, but I couldn't find anybody else with the symptoms that I am having.



Yesterday, after I filled up with gas, my bike started to die while idling. Now it WILL stay running with a little coaxing of the throttle, and I did have it going earlier with the gas cap off, and the choke on. As soon as I killed the choke it stalled. Bummer. And I haven't been able to duplicate the results. I remember the bike doing this to me once before, a few weeks after I got it, but it went back to running fine the next day. Both times, I had just filled up with gas, so I'm really stumped... I was thinking the air hole in the gas cap may be clogged, but I fooled with it and that doesn't seem to be it. Any help would be greatly appreciated.
 

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Mine has been doing that too but it seems to be in direct relation to the mixture screws for me. I'm always adjusting and noodling and changing things and if I have them set overly rich then the bike will stall on me when I come to a stop at a light or stop sign. I have been slowly leaning out the needles and then readjusting the idle screw and it's been getting better. Seems like there is that small window where the mixture screws and idle match up and when I hit that magic setting the bike runs awesome and idles smooth and consistent, and thats also when my plugs are looking just right as well. Could be something entirely different in your case but you never know.
 

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Must be the alignment of the planets or something strange like that
LMAO

My GL500 has just started doing this as well in the last couple of days
 

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Discussion Starter · #5 ·
Alright, I think I've ruled out the vent hole in the fill cap, and I'm trying to move on to the next option. Should I try and adjust the idle screws? I'll check the fuel filter in the morning. What about petcock problems? Any sugeestions on petcock troubleshooting? Sorry guys, just trying to figure this out so I can ride it to work tomorrow worry-free...
 

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That seems to have happened to me too, after I would add some seafoam, or recently, after my cousin poured in some lucas oil cleaner. It runs better now, It just needs calibrated better with my mixture screws I guess. I have a tacho on the way to do that.
 

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I'm guessing since you have a 78 you have the early gravity feed petcock/carb setup, with the fuel intake on the left side? If so it's pretty easy to see if you have fuel flow, that's what I would check first. After checking that it could be many things, like Dave said check your spark. Also, what shape are your carbs in?
 

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I just went through something similar...my end result after thinking of and testing what seemed like everything under the stars was what I will call an air-leak. I did clean the carbs though, so it could have been debris or dirt in the smaller jets...but I think it was loose clamps.



Confirm the three basics before moving to anything else...Air, Fuel, Spark, then start to move on to other things.



Check your clamps that hold the carbs, both sides...I believe that was the culprit on mine. My most recent post on the Technical Forum has lots of good info from a lot of different people, all great advice.



Its been asked what shape are your carbs in? have you ever cleaned had the low idle jets out and cleaned them? The one I am talking about is the middle one contained by the rubber plug--this one is the most problematic for most bikes.
 

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Discussion Starter · #10 ·
I can't get that little clamp off the fuel hose leading from the petcock to the carburetor. So frustrating.



Also, noob question here, what is the correct way to check for spark and air? This is my first time actually working on the cycle since I got it in March.



And about the carbs, I personally have done no work to them since buying the motorcycle, and the guy I bought it from wasn't sure either. So they may never have been messed with. I also want to adjust my cam chain and tappets, but I'm not real confident I can do it properly.
 

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I can't get that little clamp off the fuel hose leading from the petcock to the carburetor. So frustrating.



Also, noob question here, what is the correct way to check for spark and air? This is my first time actually working on the cycle since I got it in March.



And about the carbs, I personally have done no work to them since buying the motorcycle, and the guy I bought it from wasn't sure either. So they may never have been messed with. I also want to adjust my cam chain and tappets, but I'm not real confident I can do it properly.


Those stock clips can be a small challenge...I use a tiny pair of hooked needle nose, insert the tips into the little holes and open them up and push the wire clamp back. Once you get the clamp back, removing the older hose can be a challenge too...just be patient, and you can often time gently pry the hose off using a flat screwdriver. Sometimes the hose will get 'stuck' onto the hose barb, and can take a little finess to break its seal.



You can remove the plugs, insert the plug into the cap/plug wire, and with the threads touching a solid ground like the frame, you can roll the motor and watch for spark. Just be cautious as you can get quite a jolt if you are touching the frame or plug...make sure you are clear.



If the carbs have never been serviced that you are aware of, I would assume the have not been touched, or for that matter somebody did fool around with them and you have no idea where things are at.



I would HIGHLY recommend Larry Cargill's carb book. I bought it and it helped me get through mine. Well worth the money.



Start with those things and then worry about the tappets and cam chain when you get her at least runnin steadily.



A couple things come to mind as to why it is stalling...either an air leak, or a blocked or clogged up Low Idle jet/circuit inside the carbs.



As far as air, check your air filter...maybe you need to replace it.
 

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Discussion Starter · #12 ·
As a beginner, how difficult would it be for me to properly rebuild my carbs following Larry's book? Also, what would be the length of time my cycle would be down, if I worked on it religously all day for 2 days? What materials (kits) would I need? I'm on a super tight budget, with really no more than $30-40 to spend on this right now. I've got me a baby on the way!!!
 

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Congrats on the soon to be new arrival...THAT is the good stuff!!
I have two myself.



Check around as I am sure there are some people in your area that might be able to lend a hand. Depending on the condition of things you may need some rebuild kits as the gaskets can get pretty cruddy, brittle etc. 30 to 40 IS a very tight budget to do the carbs via Larry's way...I think its doable though depending on how the insides and gaskets look.



You can do a good cleaning even without the ultrasonic cleaner, maybe someone close has an ultrasonic cleaner they could let you borrow--as this IS the best way. You will have to break down the carbs though and evaluate the pieces parts and determine what ABSOLUTELY has to be replaced and go from there.



The biggest thing is to be patient--its tough. I have waited my whole life for a bike, and to get mine rolling well took me nearly 8 months. I am a single income and don't make a killing at work, but you'll find the money, it just comes down to that patience game.
 

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If you have Larry's book you should be able to do a pretty good job of cleaning them without having to spend much money. The 2 parts I can think of that usually need replacing are the rubber bowl gasket and the ACV's, but if your gaskets are in good shape you can reuse them and if the ACV's are perforated you can just make a solid disk and plug them. Like Rick said, be patient and DON'T force anything, I ruined a set of carbs trying to unscrew the low jet and ended up having to buy a whole set from Larry.
 

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I have some tools I could loan to you, I might have some old parts that could work depending on the condition of yours. I even have a couple extra rubber stoppers for the inside of the carbs if you need them. I got my ACV's (air cut-off valves) from Sirius Consolidated Inc and I think I paid 15 dollars for the two of them?



Make sure you don't just soak the carbs without understanding what's involved in rebuilding them Some cleaners you may use EAT rubber and some of the important bits like the ACV's...gaskets etc.



Larry's book is invaluable and worth the purchase price...I understand you are on a budget too. There are a lot of disucssions on here about the carbs though...maybe work to take them down, dissassemble them without splitting them (separating them from the brackets that hold them together) There are a couple of tricky parts along the way, but if you have any questions, search first, ask after searching, all of this before you move or work on them so you don't break anything or impart any damage.
 

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If this was the first time you filled the tank all the way and you don't have an inline filter for the gas, I would suspect maybe you flecked off some rust from the upper reaches of the tank, which are now in your carb.
 

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If this was the first time you filled the tank all the way and you don't have an inline filter for the gas, I would suspect maybe you flecked off some rust from the upper reaches of the tank, which are now in your carb.


haha...having gone through this, and still having a lightly rusted/frosted fuel tank this is a strong possibility.
 

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Discussion Starter · #18 ·
Well, I fooled around with the motorcycle today, and the carbs look to be in okay shape, as far as I can see, but I couldn't get them all the way out to break them down. I couldn't seem to get the trottle cables loose, and just got frustrated and hot, and bolted them back in. Brought it home to my house (was working in my dads shop) and parked it until I really have some time to work on it. I guess for the time being, I am cycleless.




PS: There was a bunch of grime on the outside, and they did look like they probably haven't been messed with for the past 33 years.
 

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Discussion Starter · #20 ·
Alright, I finally got to do a little tinkering last night, for the first time this week, and I've narrowed it down to air. When I half-assedly-gave-up pulling the carbs, I managed to kink the choke cable, making it completely unusable. So, I while trying to get started last night, I pulled the clutch on the carb by hand, and noticed what felt like something spinning against my finger. After much thought about that, I'm damn near convinced that was an air leak I felt on my finger. So I'm guessing one of my carb boots has a hole in it.
 
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