82 GS550 starting/running woes

[VinnySem]

I have an '82 GS550 that has trouble starting and staying running once I get it turned over.
I just completed cleaning up the carbs; I completely disassembled, dipped & sprayed, replaced all the O-rings and gaskets, and bench sync'ed, per the CV carb docs here and on BassCliff's site. I installed new intake boots & O-rings. I replaced the petcock vacuum tubing.

Symptoms:
The engine will not fire without a shot of starter fluid. Once it starts, it will not stay running without some choke, even once warmed up. If I give it any throttle, the engine dies. I have the idle maxed, and idle RPM is less than 1K. If I partially block the air intake with my cupped hand, the idle races to over 3K. I checked the fuel flow; with the petcock set to PRI, gas will run freely out the float bowl drain if I open one. All cylinders are getting spark. The engine does not run rough or backfire.

Can anyone offer some troubleshooting steps?

Thanks for the help,
Vin

[hikermikem]

do you have the airbox installed??

Have you adjusted the valves yet??

[VinnySem]

The airbox is installed, without the filter.

I have not adjusted the valves. Does the mileage on the bike matter with respect to the valves needing adjustment? The engine has just over 10K miles.

One thing that was suggested to me by a very knowledgable mechanic was that i may have backed out the mixture pin too far (2 turns) and the mix is too lean. Thoughts?

[duaneage]

Check the diaphragm covers to make sure the screws are tight and they are sealed. Leaks there will dilute the mixture and muck it up. The boots need to be tight on both sides of the carbs and the air filter should be in place. The restrictions provided by the air filter draws fuel into the venturi. Check the sealing rings for the choke valve, on the side, where the choke rod actuates the choke for tightness and leaks.

I assumed you set the float levels right, usually 22 mm from the gasket edge with the carb upside down to the float tang.

I think there are air leaks somewhere, PM TheBigRed and talk to him about what he found because he has the same engine and had similar problems after the rebuild

[VinnySem]

Thanks! I will try that when i get home from work.

[hikermikem]

The airbox is installed, without the filter.

I have not adjusted the valves. Does the mileage on the bike matter with respect to the valves needing adjustment? The engine has just over 10K miles.

One thing that was suggested to me by a very knowledgable mechanic was that i may have backed out the mixture pin too far (2 turns) and the mix is too lean. Thoughts?

Put an air filter in the airbox before adjusting the mixture... I believe the mixture richens up as you turn them out, not gets leaner...

According to the Suzuki service manual your valve clearances should have been checked almost 4 times by now (600, 4K, 7K 11K)... I would buy an OEM valve cover gasket & check them... tight valve clearances contribute to hard starting.

Do all the stuff duaneage has recommended as well - air leaks are a constant issue here.

good luck,

mike

[duaneage]

turning the air screws to the left adds more air to the mixture. This only matters at idle since above idle the air screws contribute very little.

[BassCliff]

Greetings and Salutations!

Hi Mr. VinnySem,

How did you slip in here without me giving you the unofficial welcome? I know you've seen my site, but let me roll out the welcome mat for you...

Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Pay close attention to the "Top 10 Common Issues" there in the mega-welcome. Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[hikermikem]

turning the air screws to the left adds more air to the mixture. This only matters at idle since above idle the air screws contribute very little.

Thanks duaneage, I had it backwards !!

[VinnySem]

Thanks for the tips and the welcome mat!

So turning the airscrew clockwise richens the mixture, correct?

I will install the air filter first, and order the valve cover gaskets from Bike & Bandit.

BTW, a tip I'd like to share: to clean out your jets, try using a piece of high-E guitar string from an 8 gauge set, and a piece of low-E from the same set as a feeler gauge from the same set

[VinnySem]

Ok, the more I get into this bike, the more I wonder WTF the previous owner was doing. I think he may have mixed up the spark plug cables! I have a repair manual but have not been able to find a cylinder layout diagram or firing order. Can someone help me out?

[BassCliff]

Hi Mr. VinnySem,

Cylinder #1 is by your left leg as you sit on the bike. On my bike the firing order is 1, 2, 4, 3. Yours should be the same. The GS bikes use a "wasted spark" system. That means it also fires on the exhaust stroke as well as the compression stroke.

Did you download the Suzuki Shop Manual from my website? There are manuals for the 8-valve and 16-valve (TSCC) versions.

Thank you for your indulgence,

BassCliff

[duaneage]

The spark plug boots on the wires are different, usually the longer one goes on the inner spark plug. They should be marked too, but not always. After you figure this out use a permanent marker to label the wires

[atchbo]

Hi. I'm a total newbie, but from what I've read, if you don't have the filter on there, you'll be totally lean (even without any other leaks). That might explain why the choke helps.

Atchbo.

[VinnySem]

So just to make sure, the cylinders are numbered from left to right 1-2-3-4, and the firing order is 1-2-4-3.

I bought the original repair manual, instead of downloading and printing. Strangely, I couldn't find the info.