Oh No, yet another carb thread... [hesitation at 6-7k,...] [Update Mar 25, 2008]

[simon79]

Hello, all.
Riding season has begun for us in the northern hemisphere, so I can test-ride my bike a little better now.
A few months/weeks ago I checked and adjusted my valves (.06-.07 mm now all of them) and changed oil & filter.
Everything as per the manual and so.
Now,
I'd say the bike is running well, BUT not so well as I'd expect (or I'd like to be).
Here's what makes me think.

• i) I get some throttle hesitation around 6000-7000 rpm under load (say 4th-5th gear?), nothing dramatic, but it feels like that;
• ii) fuel mileage is not bad altogether, I get 50-55 mpg. Thing is, I read about people doing 60-65 or even more...and I usually shift at 5000-6000 rpm, rarely more than this. Hmmm, there's something I don't get. I think I should get better mileage given my riding style.
• iii)Something happened the other day during a ride with a friend. We were going uphill on a very tight and slopey (sp?) curve, I nearly stopped to make a slow-speed maneuver...I stood still with front wheel uphill for a few seconds, and my GS nearly died as if it were drowning. A couple throttle twists got it back, but I was surprised. A few seconds up a slope IMHO shouldn't cause and (even carburetted) engine to nearly die.
• iv) Maybe linked to i), I seem to get little high-end power. My bike will struggle getting 100 mph (not that I want always go that fast, rather the opposite...speed is not my cup of tea), and even then it feels a bit rough. Tested it today on the motorway.
• v) When I rev the engine in N, rpms go back down a little slowly. (lean??)
  

Now, a few things about my bike.
As said, valves are ok, adjusted not so long ago (say 600 mi?), and oil and filter are new.
Plugs are more or less like #23 on this page, maybe the threads are even cleaner than this.
Idle is ok, normal operation is quite smooth.
'01 model, 32800 km (20385 mi) of which 8000 (4980) done by me.
All stock (dunno about the carbs, perhaps PO had an aftermarket exhaust on it, so it might be custom jetted).
I'm afraid it's finally time to tear the carbs apart.
Thoughts anyone?
thanks in advance.

PS: I know there are plenty of threads about carb problems, I read many of them and gathered some useful info from there, but I decided to post my symptoms 'cause I seem to have a combo of both "lean" and "rich".

[ohgood]

i wonder if your intake pipes are cracked. mine are. it sucks - er it sucks more air in, a little leaner and runs like crap. i rigged up some rtv to see if it helped. it did. i wouldn't ride like that though. little piece of something could wreck the engine.

[simon79]

^^^^^
Thanks mate.
I gave a look under there. Didn't take off the carbs yet (not something I feel comfortable working on, I admit... ), anyway I noticed that three intake boots fasteners out of four (excluding left airbox side) weren't quite tight. I tightened them up, went for a short ride and seems to have improved, no hesitations anymore. I recall having done this another time before. Vibrations maybe...
Air mixture screws could help?
Any more suggestions/thoughts welcome.

[ohgood]

ya, you could do that. if you search the forum for 'plug chop' you'll find a way to determine which area needs attention.

so long as it's running right and it's not lean, <shrug> just ride it. no need in introducing it to problems

[simon79]

"Plug chop"...yes, I read about it some time ago, I know more-or-less what you're talking about. Might well give it a try if issues persist. Thanks again.
...I agree with you, that's why carbs scare me to hell

[simon79]

Update March 25, 2008.
Something happened in the last few days.
I decided to give a try on the air mixture screws located underneath the carbs, giving 'em both half a turn in (=leaner mix). Together with the carb boots' C-clamps tightened, things actually improved, for the last few days my bike ran like a champ.

Till today.
On a quick town ride, the engine started to bog, so I assumed (realistically) that I was low on fuel, so I switched to reserve. After a few hundred metres, I realized that low fuel was not the issue. The bike was running really poor. So I pulled over, trying to give throttle, but it would drown. Idle would go up and down erratically, adjusting it with the screw was of little use. And a pool of gas was coming out of the drain hose. Bloody hell.
And now I remember:

iii)Something happened the other day during a ride with a friend. We were going uphill on a very tight and slopey (sp?) curve, I nearly stopped to make a slow-speed maneuver...I stood still with front wheel uphill for a few seconds, and my GS nearly died as if it were drowning. A couple throttle twists got it back, but I was surprised. A few seconds up a slope IMHO shouldn't cause and (even carburetted) engine to nearly die.

So back at home I went, took off the tank to see if I'd done something wrong last time, but I was skeptic at it since I'd been riding several kms during Easter weekend, without no issue whatsoever.
All clear, except for a terribly sooty right plug.
I went to my local Suz dealer (a couple mins from my place), who took a quick look at the bike and said, -One [or both] float valve needle is prolly shot, no time until next week to fix it... Gas leak from the drain hose is a clear sign.-
And I assume he may be right...I checked float levels a few mins ago, both seem to be a bit (5-6 mm?)(1/4''?) above gasket level.
Time for a carb job/clean/sync I think...next week hopefully.