Adjusting A/F Ratio

[klarowe]

I have had a few minor running issues lately and my dad and I both believe it may be the Air/Fuel mixture. I know that there are adjustment screws on the carbs, but how do you go about "tuning" it?? is there a simply DIY method or do I need to bring it somewhere to have it tuned?
Here is what has been happening.
Day 1 (about a month ago): Took it for about a 2 hour ride.. speed ranging from 30mph to 55mph). After about an hour and 15 minutes I lost power and died out. I let it sit for about 15 minutes and it started up and ran great. That same trip, my horn shorted out (yes, it was quite amusing when it would just randomly go off for sometimes 10 seconds or more). I replaced the horn, replaced the recently replaced turn signal relay, and put a new battery in it.
Day 2 (last week): Took bike to work, was on the highway (about 60mph) for about 5 miles and it started to lose power and ended up dying right out. It wouldnt restart at first but when I turned the fuel to PRI it fired right up and ran fine again. After a mile or so i put it back to ON and it ran fine the rest of the way to work. I checked the gas cap and it seems to be ventilating just fine.
Day 3 (Monday): Took bike to work avoiding the highway as I have been doing and it seems to do fine. On my way home it was quite warm (about 80 deg) and about 1/2 way home i come to a stop at a light and it just immediately starts to stutter and shuts off. Takes a little while to start, but eventually starts up again but will not idle on its own. I had to either keep the choke partially on or keep on the throttle. When i got home I let it sit for about 15-20min and it would idle fine again.

In addition to the above, there is always a slight hesitation anytime you get on the throttle hard, and always at between 4500rpm and 6000 rpm. Any other ideas besides A/F mixture? The carbs were supposedly rebuilt last year and when my dad and I pulled the airbox and diaphram cover off, they seemed to be spotless so I am thinking the carbs are fine.

Once again, sorry for the book, but I try to make sure you have all the details b/c I know how good you guys are... lol

Kenny

[bwringer]

Exactly what sort of vehicle might be under discussion?

Have the valve clearances been checked recently (within the last 4,000 miles)?

Are the intake boots of recent vintage? How about the o-rings, if present?

Is the airbox present and sealed? How's the air filter? If you're using pods instead, has the jetting been updated to match?

Exhaust original or aftermarket? Any jetting changes?

[klarowe]

Lol.. all the details and I leave out the most important.. lol
1) 1983 GS550E
2) I just picked the bike up about a month and a half ago. I am unsure if they were done when the carbs were redone. Is it something I can do with intermediate engine knowledge?
3) The intake boots appear fine. The clamps are missing, but there do not appear to be any leaking from the boots or airbox. I am unsure about o-rings... I dont remember seeing any when we pulled the airbox/boots off.
4) Airbox is present and sealed to my best knowledge. Air filter seems to be in pretty good shape. No pods.
5) Exhaust is original. No jetting as far as I am aware.
Thanks

[bwringer]

For starters, you definitely need to replace those missing clamps. They're less than $3 each from Suzuki. I don't know of any aftermarket or generic clamps that will work right.

You do seem to have symptoms of intake air leaks. Other problems may crop up, but first you have to fix those leaks and then go from there.

I don't think your machine has o-rings under the intake boots.

[klarowe]

what is the fluid that I can spray around that if it gets sucked up it will make the rpms raise/lower? I am drawing a complete mind blank.

[bwringer]

what is the fluid that I can spray around that if it gets sucked up it will make the rpms raise/lower? I am drawing a complete mind blank.

If you have a really large air leak, WD-40 or just about anything flammable and relatively harmless to the rubber will help detect it as you describe.

However, for most air leaks you actually see, this type of test is useless. The air leaks are large enough to affect the way the bike runs, but not large enough to suck in enough WD-40 to change much of anything.

If there are no clamps on the intake boots between the engine and the carbs, they ARE leaking air. There should be a clamp on either side of each boot. Just one loose clamp will cause a bike to run badly. Eight entirely missing clamps, well...

There should also be a clamp on the carburetor side of the boots between the airbox and each carb. These are likewise not optional.

While you're waiting for new clamps to arrive, check the valve clearances. Sorry, this is not optional and you can't judge this by the way they sound.

[klarowe]

on my bike, there are only 2 intake boots so it should be only 4 clamps. I'll see if I cant find how to check the valve clearances using the Search function... lol.
Thanks

[klarowe]

the only thing I dont get is that why is it only doing it after the bike has warmed up? also, other than the stalling out, it seems to run fine on backroads... ie, stop and go low rpm.

[Big T]

the only thing I dont get is that why is it only doing it after the bike has warmed up? also, other than the stalling out, it seems to run fine on backroads... ie, stop and go low rpm.

What's your baseline for comparison?

The symptoms you describe demand attention. Running lean will harm your engine.

What do your spark plugs look like??

BTW, the going a ways and dying is either

1. The vent in the gas cap is clogged and your bike is running out of gas
2. Your petcock is toast and not flowing enough gas
3. The floats levels are all wrong
4. The vacuum hose has a leak or is hooked up wrong

If the carbs were "rebuilt" they're probably done wrong. Take them off, pull the float bowls, check the float height and inspect jets and passages for cleanliness and blockages. All easy stuff. Check your jet sizes and compare to stock. Put them back on with the new clamps and let us know what you find

[klarowe]

ok.... i'll see what I can do... I may have to wait til after next week b/c I have my dmv road test and the last thing I want is to not be able to get it back together in time... lol. I'll just make sure to take it extra easy