Project: 1985 GS550ES

Pilot Screws 1 & 3 Still Stuck - I Give Up!

Well, not really. Today I took my carbs to a local custom shop that swore that they had the tools, time, experience and patience to either get the stuck pilot screw out or at least not destroy the carbs while trying.

I have no carbs and therefore no bike until at least Tuesday. Until then, I'm crossing my fingers and toes. [-o<

I couldn't make it bigger without blurring it - but if you notice, there is a picture of a fire extinguisher too (in case anyone reads this thread and decides to use propane - lol).

A fire extinguisher (at LEAST one) s/b part of EVERY garage/work space.

Yeah, I've seen the manometers before. Just haven't ever laid hands on one. The http://www.carbtune.com/ looks like the best, but it's a bit pricey.

Right column - 2nd pic down is a mannometer



I couldn't make it bigger without blurring it - but if you notice, there is a picture of a fire extinguisher too (in case anyone reads this thread and decides to use propane - lol).

I have two motorcycles - the Honda carbs have a screw on each boot from the carb to engine that has to be removed then the vacuum hose is inserted and sealed - there are 4 on the Honda and yes, you are right dual carbs on the GS 550 so I would only need two vacuum hoses for the Suzuki. I should have explained I would be using this for both bikes.

The mannometer I saw the guy use on my honda when I had them synced was his own design - he measured the vacuum of each carb then adjusted the air/mixture screws on each carb to get it to idle correctly. There was just one screw that was out of sync by a hair that was causing it to idle erractlically. If I remember correctly, he had a gauge at the end of each hose that looked much like a tire pressure gauge (not the pen type gauges - the circular ones that has a needle) and set them all to 30 psi on the nose. I will do an internet search and see if I can find a picture of what I am trying to explain in words.

Since you have the dual carburetors, you can build your own carb balancing tool easily. I did a search and found an example on a BMW site since the BMW's are two cylinders. Its pretty basic: A 20' section of clear rubber hose with some liquid in it. You put each end of the hose on the vaccum port of each carb. Then you loop the center of the portion of the hose into a tall "U" shape and attached it to something (like a yardstick). This means that when the left carburetor pulls more vaccum than the right, the left portion of the "U" shaped water column will pull up, and vise versa for the right carb. When the carbs are balanced, the "U" shaped column of water will be level at the tops. I have some pictures at home of how I did mine. I'll post them later. Sorry, this is, once again, something hard to explain in writing.

I also learned on "Bill Nie the Science Guy" how to make a volcanoe out of vinigar and baking soda...maybe I'll start a different thread for that.:-D

I'll definitely take a look at your own picks and any links you might have to the BMW setup. Thanks!

Vinegar + baking soda = volanco? Sounds more like an episode of Mythbusters.

I am going to see if I can get some tire pressure psi gauges - four 3 foot 1/4 inch hoses, and something I can use to place in the intake boot screw holes and attach to the hoses. I am also going to use a 2 litre coke bottle to put gas in, run tubing to the main gas line and plug the petcock vacuum hose as I adjust the carbs. Maybe then I will have solved part of the mystery of the high idling.

Four? I think we only need two since we can only adjust the 1&2 together against 3&4 together.

Intake boot screw holes? I don't understand...

I like the two liter "gas tank" idea.

PS: Is your Suzuki really a "CB" 550 E? (Check your signature)

I tried this and it didn't tell me anything, but my leak was on the vacuum hose.
Have you replaced your hoses with clear ones? The local shop just gave me a few short lengths of this to replace my old black ones. This will help you diagnose.
good luck
j

Yeah, I'm pretty much not gonna mess with propane. :shock:

Actually, I'm planning on getting new fuel and vacuum lines tomorrow.

Thanks!

Since you have the dual carburetors, you can build your own carb balancing tool easily. I did a search and found an example on a BMW site since the BMW's are two cylinders. Its pretty basic: A 20' section of clear rubber hose with some liquid in it. You put each end of the hose on the vaccum port of each carb. Then you loop the center of the portion of the hose into a tall "U" shape and attached it to something (like a yardstick). This means that when the left carburetor pulls more vaccum than the right, the left portion of the "U" shaped water column will pull up, and vise versa for the right carb. When the carbs are balanced, the "U" shaped column of water will be level at the tops. I have some pictures at home of how I did mine. I'll post them later. Sorry, this is, once again, something hard to explain in writing.

I also learned on "Bill Nie the Science Guy" how to make a volcanoe out of vinigar and baking soda...maybe I'll start a different thread for that.:-D

I am going to attempt to build my own mannometer

I am going to see if I can get some tire pressure psi gauges - four 3 foot 1/4 inch hoses, and something I can use to place in the intake boot screw holes and attach to the hoses. I am also going to use a 2 litre coke bottle to put gas in, run tubing to the main gas line and plug the petcock vacuum hose as I adjust the carbs. Maybe then I will have solved part of the mystery of the high idling.

I also heard one person say you can use propane to tell if there is a leak in your boots (I wouldn't try it myself though). The concept is to turn the gas on while the engine is running and place the gas near the boots, if the engine fires rapidly then there is a leak. I wouldn't want to find out the hard way if the propane gas ignites (I don't understand enough about it to try).

I tried this and it didn't tell me anything, but my leak was on the vacuum hose.
Have you replaced your hoses with clear ones? The local shop just gave me a few short lengths of this to replace my old black ones. This will help you diagnose.
good luck
j

No, your plug read is off. Your plugs are slightly white. That means lean, which indicates carb boot leak. Did you replace your carb boot o-rings? The ones I pulled off of my 83 cracked when they fell to the ground. They were D E A D.

In the process now. I've gotten the old ones off. However, neither the boots or the rings look particularly bad. As far as I can tell, the rings are bit flattened (as you'd expect) but everythings still pretty soft and maleable. Next session I'll be putting the new stuff on and doing everything I can to seal as I go.

[Nerobro]

No, your plug read is off. Your plugs are slightly white. That means lean, which indicates carb boot leak. Did you replace your carb boot o-rings? The ones I pulled off of my 83 cracked when they fell to the ground. They were D E A D.

Noticed your from MD - DC area. I went to Gallaudet University for 6 years (am deaf) on Florida Ave NE :-D I know a deaf mechanical wiz in Laurel named Dusan Jaksic whom may have a mannometer. I also heard one person say you can use propane to tell if there is a leak in your boots (I wouldn't try it myself though). The concept is to turn the gas on while the engine is running and place the gas near the boots, if the engine fires rapidly then there is a leak. I wouldn't want to find out the hard way if the propane gas ignites (I don't understand enough about it to try).

Yep, I know Galludet. I've been by there many times. I was always fascinated that they had a football team and I learned that they used a drum to "call the snap"...I still think that's genius!

I don't think I'll be going the propane route. :-| I'm currently replacing the intake boots and o-rings as they're the likely culprit. I aslo need to address the union of the air box and boots. After that, I'll get into the finer carb tuning and I may very well contact you about getting in touch with Dusan Jaksic. Thanks!

Noticed your from MD - DC area. I went to Gallaudet University for 6 years (am deaf) on Florida Ave NE :-D I know a deaf mechanical wiz in Laurel named Dusan Jaksic whom may have a mannometer. I also heard one person say you can use propane to tell if there is a leak in your boots (I wouldn't try it myself though). The concept is to turn the gas on while the engine is running and place the gas near the boots, if the engine fires rapidly then there is a leak. I wouldn't want to find out the hard way if the propane gas ignites (I don't understand enough about it to try).

I have a 1983 Nighthawk CB 700 SC that did the exact same thing you are describing. High idling. It would actually idle at 2,000 rpms when cold then shoot up to over 5,000 rpms and stay there. I could not figure out what it was and took it to a friend of mine who used a mannometer (sp?) to synchronize each carb. That did the trick. Each jet needle has to have the same vacuum pressure if my understanding is correct. There were 4 on my Nighthawk and there are 4 on my GS 550 E.

You might want to see if your carburator linkange is bent as well. OEM?

Well, I've done the bench syncing. Once the carbs are back on and I've looked at all the air leak stuff, I'll defintely have to properly sync the carbs given your experience. Thanks.