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Discussion Starter #1
Hi all!

Okay so the carbs are rebuilt and the bike runs very smooth now. I synced the carbs today, but did not take the time to adjust the air mixture screws. I set them at 2.5 turns prior to installing the carbs. After test driving the bike, I can tell that the idle mixture is a little lean as there is a little bit of popping in the mufflers (unfortunately free flowing mufflers all thanks to the previous owner who sawed off the silencers).

Anyways, I tried adjusting them this evening and I honestly did not notice much of a difference in RPM with the air screws all of the way in. There was a very tiny RPM reduction (which is to be expected) with the screws all of the way in. But just as soon as I turn one open, the RPM barely increases at about 1/2 a turn from seating (zero position). I would back them out 2, 3, and even 5 turns and there was no difference; that is, no RPM increases or smoothing out.

Out of curiosity, for those who own (or have owned) GL1500's, how many turns did you have to adjust the air mixture screws? Right now I have them set at 2.5 turns just for the sake of it, but it feels a little lean.

Joe
 

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What is your rpm set t idle,750 is close,if it idles fine out will be good to go,there may a little issue causing the screw adjustment but finding it might be a monumental task,since it only effects the motor at idle just ride it with some njector cleaner in the gas and ride it,might be a change after riding a while.
 

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Discussion Starter #3
What is your rpm set t idle,750 is close,if it idles fine out will be good to go,there may a little issue causing the screw adjustment but finding it might be a monumental task,since it only effects the motor at idle just ride it with some njector cleaner in the gas and ride it,might be a change after riding a while.
I have it set about 800 RPM, which I assume is the line on the RPM gauge just below 1,000 RPM.

Joe
 

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I have it set about 800 RPM, which I assume is the line on the RPM gauge just below 1,000 RPM.

Joe
I agree with Texas. If the bike runs with the mixture screws turned in all the way, (idle mixture turned off) the engine must be getting fuel from somewhere else. I would turn the RPM down the 50 RPM and try again. It probably will not make much difference but who knows. It is fairly common to end up with this issue. If it is the only symptom it shows you might be just fine leaving it alone. Might be you have the fuel level a fuzz high. worn throttle shafts etc. If it runs good and gets decent mileage I wouldn't mess with it too much. :)
 

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Anyways, I tried adjusting them this evening and I honestly did not notice much of a difference in RPM with the air screws all of the way in. There was a very tiny RPM reduction (which is to be expected) with the screws all of the way in. But just as soon as I turn one open, the RPM barely increases at about 1/2 a turn from seating (zero position). I would back them out 2, 3, and even 5 turns and there was no difference; that is, no RPM increases or smoothing out.
Out of curiosity, for those who own (or have owned) GL1500's, how many turns did you have to adjust the air mixture screws? Right now I have them set at 2.5 turns just for the sake of it, but it feels a little lean.
Joe

Obviously not right if adjusting the fuel mixture screws has no affect. On a properly running 1500 turning the screws 1/2 turn either way from optimum makes a noticeable change. Back to the drawing board.:?
 

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Slow the idle down and try the screws,it is low speed idle and high rpm won’t give you the results you need.
 

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Discussion Starter #7
I corrected the problem. Idle was too high, closer to 1,000 RPM. I reduced it to about 700 RPM and I noticed the change in engine RPM when turning in the screws. I ended up with 3.5 turns on the right carb, and 3.75 turns on the left. I then had to re-sync the carbs, and just to be sure, I rechecked the mixtures screws, and both are now about 3.5 turns. Engine runs great! Instant power when the throttle is advanced.

So I'm enjoying my ride today, when all of a sudden, I had the same problem that I had last year on Thanks Giving. If you all recall, my bike started dying on me on the way back from the trip. I presumed it was bad fuel. Well today, it happened again only much worse. This time the bike sputtered and completely shut down. I popped the gas cap to check for it being stuck. The bike restarted but as soon as I throttled, the bike started sputtering and shut off again. Took me about 15 minutes to make it home with this condition as I was only able to do about 25mph.

I put the bike on the maintenance stand and was able to duplicate the problem by engaging the choke, which starved it for fuel. I knew at this point it was either the auto-petcock again, or the fuel pump.

Long story short, the petcock on/off seal (front one) was popped off of its bushing/holder and stayed in the close position and was also stuck to the body again. I'm thinking what happened is the rear diaphragm was trying to open the valve, but the front (on/off) diaphram was stuck, and pulled itself free from its keeper. I also noticed that the rubber was not necessarily dissolved, but very flimsy and sticky. Luckily I ordered the rebuild kit last week and it was sitting in the bike since the last time I checked it a few days ago. So tonight I rebuilt the valve, and presto! Fuel supplied much faster and the filter doesn't form air bubbles as it had been doing.

I saw that the rubber in the new kit was much stiffer than the one I pulled out.

On a side note, I've been running Shell Nitro Premium in the bike because of its cleaning attributes. When I rebuilt the carbs a few days ago, there was almost no corrosion, all thanks to the Shell Nitro fuel. Unfortunately, the chemicals they are using in Shell Premium might be destroying or dissolving rubber seals and needle tips. I'm going to run a test on it and I'll share the result if you are all interested in my findings. Shell claims that they've spent millions of dollars in researching the best E10 fuel that will protect classic vehicles with carburetors. While it may clean them, the problem is the damage it does to plastic and rubber. Shell Nitro Premium destroyed my fuel pressure gauge (tool) by dissolving the rubber o-ring inside of the tool. I suspect it is doing the same thing to my auto-petcock.

So tomorrow I'm headed to the fuel station to fill up with non-ethanol fuel.

Joe
 

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Just low octain,works fine 87. Glad the idle fixed the issue.
 

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Discussion Starter #10
Just low octain,works fine 87. Glad the idle fixed the issue.
Yep! And I'm done with Ethanol. I still think this was all intentional to ruin older vehicles with the use of alcohol and possibly the additives (BTEX), which we now know destroys rubbers, and corrodes copper.

She's gonna get a nice fill-up of 87 non-ethanol fuel today.

Joe
 

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Discussion Starter #11
if you can find Pure Gas, stick with that.... ethanol dissolves carb parts.
Yep. I of course was testing the Shell Nitro claim that their fuel additives SUPPOSEDLY protects carb components. I'll say this much; Shell Nitro Premium is great for keeping carbs cleaned. I used it for almost a year and the inside of the carbs were completely clean. Unfortunately this comes at the cost of rubbers and seals, which the additives and the alcohol dissolves them. I'm done with this crap. I spent too much time and effort restoring the fuel system and I don't care to do this anytime soon. :grin3: Gonna fill her up with non-E fuel today.

Joe
 

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Hi all!

Okay so the carbs are rebuilt and the bike runs very smooth now. I synced the carbs today, but did not take the time to adjust the air mixture screws. I set them at 2.5 turns prior to installing the carbs. After test driving the bike, I can tell that the idle mixture is a little lean as there is a little bit of popping in the mufflers (unfortunately free flowing mufflers all thanks to the previous owner who sawed off the silencers).

Anyways, I tried adjusting them this evening and I honestly did not notice much of a difference in RPM with the air screws all of the way in. There was a very tiny RPM reduction (which is to be expected) with the screws all of the way in. But just as soon as I turn one open, the RPM barely increases at about 1/2 a turn from seating (zero position). I would back them out 2, 3, and even 5 turns and there was no difference; that is, no RPM increases or smoothing out.

Out of curiosity, for those who own (or have owned) GL1500's, how many turns did you have to adjust the air mixture screws? Right now I have them set at 2.5 turns just for the sake of it, but it feels a little lean.

Joe
Quick question on how you are turning the screws with the carbs installed?
I am thinking there is a tool, but haven’t bought anything...
 

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you have to use a very long "screwdriver" from the front. easier to remove the right side fan, but doable w/o doing that.

the screwheads are 'D' shaped... when in OEM condition, they have a plastic cap over them... those get lost quick after the first time someone tries to sync the carbs.
 

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Quick question on how you are turning the screws with the carbs installed?
I am thinking there is a tool, but haven’t bought anything...
I bought a tool years ago made for adjusting these screws has an assortment of tips for different carbs but can't remember where I bought it.
 

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I bought a tool years ago made for adjusting these screws has an assortment of tips for different carbs but can't remember where I bought it.
took a lot of searching, but it was found from our own forum several years ago, MotionPro still has it.





But at $75.00 for the complete set, I think I would just buy the D shaped bit.



at $5 plus shipping
 

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Quick question on how you are turning the screws with the carbs installed?
I am thinking there is a tool, but haven’t bought anything...
To really do it right with engine running and air box off you need this complete tool with the D bit and then set slight lean. In a pinch use the stubby Valk tool. Tie a string to it prior to using because chances are it will get dropped never to be found again in the area under the carbs, the string brings it back home in that case.


Going in from the front by the radiators as the manual recommends is an exercise in futility, lots more show than go.

.

The "90 and up models use the D bit. The "88 uses a slotted screw head on the fuel mixture screws with limiters which need removal for full adjustment. Have not had an "89 through the shop yet to comment. :unsure:
 

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I do have the Honda tool as well and is a pain to install unless you have two then it could be ok

has anybody used the motionpro tool 90 deg multiple bit on a gl1500 ?
 
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