Power problen

[Brandon.paul01]

Hey yall. I bought a 2009 gs500f almost a week ago and it does not have much power. Now i know that this bike is not a speed demon but i have trouble getting over 70. 6th gear gives me nothing but maintains speed and 5th doesnt do much. Most of my power is in 3rd and 4th gear. Ive been told that it maybe the carbs need cleaned? Better air to fuel ratio? Im not a super experienced rider and im very far from any sort of mechanic so if anyone could maybe give me some help and tell me what it might be?

[Bluesmudge]

Where are you located? In Europe some GS500s were sold with air/fuel restrictions to meet power requirements of lower level moto licenses.

Assuming you are in the US, something is definitely wrong because you should have no problem hitting 90+ MPH indicated. Are there any other symptoms like poor fuel economy, flat spots in the rev range, vibration, smoke, or smells?

[Brandon.paul01]

No other isues at all. Everything runs fine ive put over 150 miles on it since i got it and its done exceptionally well except for the power.

[herennow]

Are you using the full RPM range (not lugging the engine?)

[Brandon.paul01]

Yes full range. Shifting at 8000-9000

[The Buddha]

Lets go Brandon.

BTW you sound like a dirty air filter to me.
Yea maybe carb need clean, but air filter is easier to get at. Check and clean with gas outside to inside or replace it first.

Lets go Brandon.

Cool.
Buddha.

[tbeers]

I did this to my bike recently but haven't started it since (wrecked the bike a while ago and currently trying to solve problems) but a mechanic at my local suzuki shop told me if I put an extra washer under the needle that goes into the main fuel jet (you need to take the carbs out, pull the needle out from the diaphragm, and there will be a tiny washer around the needle. The extra washer lowers the needle out of the jet a tiny bit, but it's enough to let just enough more fuel into the jet to make a noticeable difference.

The extra washers are already in my carbs, as soon as I solve my bike's problems I'll let you know how much of a difference it makes!

[mr72]

that's known as "shimming the needle", and it actually raises the needle, doesn't lower it. It won't make any more power, it'll just make it slightly more rich at part throttle and lower RPM.

The needle limits fuel flow in the jet. Given a certain rate of air flow, the needle is raised or lowered so it meters fuel according to the part of the taper that's within the top of the emulsion tube. Putting a shim in the needle basically changes the static position of the needle so it's always richer between idle and WOT. But it'll be the same at WOT, and at idle.

IDK what the OP's power problem is, but it could be caused by a bulk vacuum leak which causes the slides to not come up at all, or stuff like torn diaphragms in the carbs or some other condition causing the slides to stay down. Or it could be caused by something like putting pod filters on and not sorting the jetting.

In any case, the solution is to do the procedure in my signature as a starting point. Just make sure the carbs are working correctly and no vacuum or fuel leaks, parts are all there and intact, and it's assembled correctly with stock parts.

[herennow]

If you have more than a few KM on the bike the Needle + needle jet is probably already worn and is already running a little rich at midrange....

[The Buddha]

If you have more than a few KM on the bike the Needle + needle jet is probably already worn and is already running a little rich at midrange....

I have rarely seen this happen on a GS. And those cases have mostly been run with a K&N left dirty in dusty conditions for a long long time. And those have worse wear on the slide and guide than the needle anyway.
Cool.
Buddha.

[herennow]

At 60k KM my jet and needle measure out of spec. Considering how small the annular ring is when the needle is at half throttle even tiny amounts of wear can be problematic.  I think that normally this is fine as bikes in the 80s were jetted leaner and leaner so a bit  of richening up is a good thing. Richening up with wear and a washer is probably too much for an old bike.

Im my british bikes I change needle and needle Jet every 20 k km on the new premier carbs. IN the old days they were done annually when folks commuted on them.  Slides are now anodised so they last much longer then before.

Coming to think of that, does anyone know where to get GS needles and needle jets. I might invest in a pair for the next service. Be interesting to compare the old and the new, especially against the Mikuni specifications.

[johnny ro]

There is a person named Derek at Moto-labs, in western USA.

He sells carb jets and can sell what you need. Has a dyno and lengthy experience. The real-deal smart guy. Sells non-EPA OEM stuff for EPA OEM equipped bikes.

I think he will agree on carb parts being replaceable wear parts.

If / when I get my GS running again he will set me up on those carbs. He was excited when I mentioned it, he worked with GS500s in his career.

[The Buddha]

There is a person named Derek at Moto-labs, in western USA.

He sells carb jets and can sell what you need. Has a dyno and lengthy experience. The real-deal smart guy. Sells non-EPA OEM stuff for EPA OEM equipped bikes.

I think he will agree on carb parts being replaceable wear parts.

If / when I get my GS running again he will set me up on those carbs. He was excited when I mentioned it, he worked with GS500s in his career.

Oh noooooooo....... I sell jets for your setup too. LOL, yea I have started back up recently though after having almost quit a few yrs. Better yet, I only sell GS jets and still own several, a couple which might even run. LOL.
Cool.
Srinath.

[sledge]

Everyone always says ITS THE CARBS!!......but try something easier first.

Count the number of teeth on the sprockets. Stock is....Front: 16 teeth. Rear: 39 teeth.

If the previous owner has been f%$king about with the ratios it will give you similar symptoms.