GS850gl carb sync gone south

[Guest]

Having shimmed the valves earlier this summer, and fixing a bunch of electrical bubbles and bobbles... My bike has been running pretty well.. but stumbling when there is no load and coming off the throttle. It's been over 2 years since I cleaned and replaced the o rings in the carbs... so I thought I might get away with just syncing them... I was wrong again. It's been idling fine ..more or less at about 1000-1100 rpm with the occasional dip that I've become accustomed to.. I got the tank off, the alternate fuel tank placed and run.. and started to adjust the idle... that's when things went south. Upon lots of problems even getting the thing started I decided to pull the idle mix screws to see where I stood.. I pulled #4 first.. looked ok..as did 3 and 2... but when I pulled out old #1 The screw came out without the o ring and the spring... I used a small hook and pulled out the spring and o ring and the spring was broken and had a white corrosion on it. Here is a picture #2 is alongside for comparison. What do you think? replace the spring.. and continue wait for the weather to change before another carb rebuild.. or just bite the bullet and start in on the tear down now?

 

[Guest]

a picture of all 4 idle screws..

 

[Steve]

What do the mixture (pilot) screws have to do with a carb sync? :-k

Now, to answer your question: replace the spring.

You might want to find out why it got damaged, though. I must say that I have never seen a broken spring on a pilot screw, so I have no idea what might have caused it. It is quite common for the screw to come out by itself. I then insert a #6 drywall screw, turn it slightly, pull out the spring. Repeat the process to remove the washer. Sometimes the o-ring comes out with the washer, other times it needs to be pulled with a third insertion of the drywall screw.

I don't see anything there that requires a carb rebuild.

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[Guest]

What do the mixture (pilot) screws have to do with a carb sync? :-k

Now, to answer your question: replace the spring.

You might want to find out why it got damaged, though. I must say that I have never seen a broken spring on a pilot screw, so I have no idea what might have caused it. It is quite common for the screw to come out by itself. I then insert a #6 drywall screw, turn it slightly, pull out the spring. Repeat the process to remove the washer. Sometimes the o-ring comes out with the washer, other times it needs to be pulled with a third insertion of the drywall screw.

I don't see anything there that requires a carb rebuild.

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LOL... I went to adjust the idle.... THAT was my mistake.. It wasn't all that bad.. but now, I've ordered new o rings and perhaps my 3rd attempt at cleaning carbs will be the charm. But after further reflection.. I'm going to replace the spring and make sure there's nothing else down the hole... Charge the battery, reset the idle, continue with the carb sync and go for a ride.

The corrosion looks like water damage so that's odd.. maybe a dollop of grease on the top of the screw after I get things back together.

 

[Steve]

You "went to adjust the idle". :-k

Idle SPEED adjustment is done with the knob under the carbs. You don't "adjust the idle" with the pilot screws.

You mention something about a third attempt at cleaning the carbs. That brings a couple of things to mind.
1. What makes you think they need to be rebuilt?
2. What shortcuts did you take on the two previous attempts?

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[Guest]

The idle had been sporadic, meaning sometimes it idled so great I was surprised... other times it died at a stop sign.. so I was trying to make a minor adjustment at the pilot screws (idle mixture) to see if that would even out the idle... it was a mistake.. but now that I found the corroded spring and lose o ring it's a mistake that probably needed to be found. #3 was 1/2 turn from bottom.. #4 was 3 turns (full 360 deg turns) off the bottom and #2 was 2 1/2 turns off bottom and #1 was... who knows how bad that was because the o ring and the spring were off the taper of the screw. I may have a sticky float causing my idle to hang a bit and my mixture also might be lean because it would idle fine and then drop to below 500 rpm and sometimes die... That's why I "messed" with the idle mixture... Also the engine was stumbling when coming off load and as my spark plugs are fouling when I take the engine even close to red line without a load.. I figured that there are other issues with my amature attempt at rebuilding the carbs the last 2 times... as I said, 3rd time's a charm... and what I've learned about me in my 65 years...sometimes it takes me 3 times to finally figure out to follow ALL the steps in the instructions... so i get it right... This will be the 3rd time... but I am going to replace the spring and the o ring.. and let the full clean/rebuild happen when the weather is too cold to ride this fall. (I've adjusted the valve clearance twice too... thinking I followed the manual pretty well..but in reading it again.. I may have had the cam lobes in the wrong position while measuring..so there's another thing I've got to check) Before you all get condescending about my repair and maintenance routines, remember I've only been riding and working on motorcycle (this one) for 6 years So every excursion into the workings of the motorcycle is an adventure, and a learning experience. I wouldn't do it if it wasn't fun and interesting.. but sometimes.. fun and interesting can be frustrating too..

 

[Guest]

The idle had been sporadic, meaning sometimes it idled so great I was surprised... other times it died at a stop sign.. so I was trying to make a minor adjustment at the pilot screws (idle mixture) to see if that would even out the idle... it was a mistake.. but now that I found the corroded spring and lose o ring it's a mistake that probably needed to be found. #3 was 1/2 turn from bottom.. #4 was 3 turns (full 360 deg turns) off the bottom and #2 was 2 1/2 turns off bottom and #1 was... who knows how bad that was because the o ring and the spring were off the taper of the screw. I may have a sticky float causing my idle to hang a bit and my mixture also might be lean because it would idle fine and then drop to below 500 rpm and sometimes die... That's why I "messed" with the idle mixture... Also the engine was stumbling when coming off load and as my spark plugs are fouling when I take the engine even close to red line without a load.. I figured that there are other issues with my amature attempt at rebuilding the carbs the last 2 times... as I said, 3rd time's a charm... and what I've learned about me in my 65 years...sometimes it takes me 3 times to finally figure out to follow ALL the steps in the instructions... so i get it right... This will be the 3rd time... but I am going to replace the spring and the o ring.. and let the full clean/rebuild happen when the weather is too cold to ride this fall. (I've adjusted the valve clearance twice too... thinking I followed the manual pretty well..but in reading it again.. I may have had the cam lobes in the wrong position while measuring..so there's another thing I've got to check) Before you all get condescending about my repair and maintenance routines, remember I've only been riding and working on motorcycle (this one) for 6 years So every excursion into the workings of the motorcycle is an adventure, and a learning experience. I wouldn't do it if it wasn't fun and interesting.. but sometimes.. fun and interesting can be frustrating too..

An added thought, I've constantly been getting between 30 and 33 miles per gallon.. I keep reading and hearing I should be closer to 40 mpg I would REALLY like to figure that out because with 3.3 gallons my range is about 110 miles which limits some of the routes back here in the west. Those extra few miles per gallon would surely add some confidence in my travels.

 

[2BRacing]

.. I pulled #4 first.. looked ok..as did 3 and 2... but when I pulled out old #1 The screw came out without the o ring and the spring... I used a small hook and pulled out the spring and o ring and the spring was broken and had a white corrosion on it. Here is a picture #2 is alongside for comparison. View attachment 56212 …...

Reading the section from your original post that I have made Bold above, you do not mention the washer. I have to ask if you have the small washer between each o-ring and spring? Difficult to see exactly in your photos.

 

[Guest]

No, there was no washer on the end... I'll be doing some fishing... the other 3 DO have that washer....

 

[2BRacing]

On my 850, the pilot screws all ended up between 2 to 3 turns out from lightly seated for best idling and response.

Your sporadic idling could have been caused by #3 only 1/2 turn out, together with uneven pressure on #1 o-ring because there was no washer.

Hope you get it sorted out soon!

 

[Buffalo Bill]

I really can't answer your first question, that's up to you.

I really can't answer your first question, that's up to you.

I don't see a broken spring here. Count the spring coils and they're both the same. The short one seems to have been over compressed, just stretch it out until it matches the others.

 

[Steve]

An added thought, I've constantly been getting between 30 and 33 miles per gallon.. I keep reading and hearing I should be closer to 40 mpg I would REALLY like to figure that out because with 3.3 gallons my range is about 110 miles which limits some of the routes back here in the west. Those extra few miles per gallon would surely add some confidence in my travels.

Yes, there is definitely something necessary in the adjustment department. I still need to fine-tune my bike, too, as I am getting a bit less than I would like.

As an example: we just got back from a week-long ride that totalled 1659 miles. The bikes were well-loaded.

Here is a record of my gas mileage for the trip:

The first tank was at higher speed, just getting across oHIo. The second tank got us into the mountains of WV, including being stopped by a multi-car accident and the detour around it. After that, it wasn't so bad, but could have been better.

How much better? Here is the record for my wife's bike. Note that both of our bikes are 850s.

Her bike has always gotten better mileage than my bike. I know it's not just the carbs, as I have swapped carbs for a solo trip, and got about the same on my bike, so I'm not sure what all it might be, but your 30-ish MPG is definitely low.

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[Guest]

I'm now wondering where the washer went... did I not put it on during the rebuild?... was it made of a different metal and THAT's the white "corrosion" on the spring? The spring itself is fine.. but, like has been mentioned, it is over compressed.... I have until friday for the new mixture screw kit gets here.. as the other 3 look fine I ordered 3... I told the guy I bought them from on ebay, " I only need one..but I will have the other 2 to add to my collection of bits and pieces that I hope to never need again."

 

[Guest]

One of these things is not like the other... one of these things just doesn't belong....

 

[Guest]

ya think this might have been part of the problem?

 

[jsandidge]

ya think this might have been part of the problem? View attachment 56216

No doubt about that. You find all kinds of PO shenanigans.

 

[Guest]

No doubt about that. You find all kinds of PO shenanigans.

Oh.. I can't blame that one on the PO... if anything it was MY lack of attention to detail or understanding of things.. I had one of the tips break off and went through hell and even designed my own tool to remove the tip from the body. My guess is I had the 3 already installed and when the new airscrew arrived I just got it in without checking if it matched the other 3.... another lesson learned.

 

[Guest]

Got the new idle air mixture screws... because of the wear on one of the "good" ones.. I replaced two of them (mis matched #1 and #3 looked a bit worn because it was closed for years?), backed them off the soft seat 2.5 turns.. got all ready to sync the carbs... and started the bike to let it warm up... after about 6 or 7 minutes.. the bike is idling better than before.. LOTS better than before. I guess having having one that was miss matched and one that was screwed all the way down.. was affecting it more than I had guessed.

 

[Guest]

Was running pretty good. As I was buttoning it up, getting ready to test the carbs on the road... I sprung a leak in the fuel supply line.... to get to the root I took the airbox off so that I could get to the hose clamp I have on the carb. after replacing the fuel line I spent about an hour trying to get the air box boots back on... then I remembered they go on better when they are attached to the carbs and then the whole shabang is remounted together... well, while the air box was off, I figured it was a good time to clean my air filter.. and then I got to looking the sad job I did on my repaint... So, already long story made longer.. I stripped the old paint off, cleaned and primed and re-painted the air box. This is the stripped box. almost a shame I need to repaint it.. a bit more shining and it would look better this way.

 

[Steve]

... so that I could get to the hose clamp I have on the carb. ...

What are you using for hoses? If you use OEM hoses, you don't need any clamps.

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