Why is my bike riding so lean?

[KatCycle]

I have a 2007 gs500f and I'm stumped! My bike is running very lean and has no bottom end power. I've gone through my carbs several times, checked for vacuum leaks and maxed out my valve clearances. My air filter is filthy and my oil is oddly clean after several hundred miles of riding. A few things I haven't tried yet: changing my plugs, taking out my secondary air filter system. I'm not going to change my air filter until I fix my lean running because I want to upgrade to pod filters (and get rid of that stupid box) and my bike should be running very rich with a dirty filter. Any ideas?

Unrelated question: What do the white caps on top of my carbs do exactly?

-Katlynn

[xunedeinx]

I have a 2007 gs500f and I'm stumped! My bike is running very lean and has no bottom end power. I've gone through my carbs several times, checked for vacuum leaks and maxed out my valve clearances. My air filter is filthy and my oil is oddly clean after several hundred miles of riding. A few things I haven't tried yet: changing my plugs, taking out my secondary air filter system. I'm not going to change my air filter until I fix my lean running because I want to upgrade to pod filters (and get rid of that stupid box) and my bike should be running very rich with a dirty filter. Any ideas?

Unrelated question: What do the white caps on top of my carbs do exactly?

-Katlynn

If its stock, and its running lean, then it may just be stock.

Maybe your choke cable is jimmied up.

Sure its lean? Pull the plugs and take a pic, if its whiter then new Hampshire winter, then its lean, if its black then its rich.

Could just be the bike. Unless im above 4-5k rpm, its gutless.

[Big Rich]

 Bear with me, I just woke up.....

Aside from loss of power, why do you think it's lean? If your air filter is dirty then air isn't going thru the carbs, which means no air/gas mix going into the engine. And you said you haven't changed the plugs, but have you pulled them out? They could be slightly fouled as well.

[KatCycle]

Yes yes I've pulled them out, white as paper. I don't think its the bike. My power issue may be just the bike and I can probably fix that by rejetting but no bike should be running this lean with a filthy filter. Thoughts?

-Katlynn

[gs500e]

You say it has no bottom end power.

What about mid & top end power?

I'm guessing a fuel flow issue (if mid and top are not real great either).

[Big Rich]

That's what I was about to say. With no air coming through the filter, it can't suck any gas out of the float and into the cylinder.

Can't the OEM filters be cleaned delicately with gasoline and a brush? Personally, I would change to whatever filter you plan on using and just rejet and be done with it.

[ballyhoo]

Be sure that the petcock is fully on. It has to be lined up perfectly open or it may result in reduced fuel flow. From off position, if you turn it too far, it starts to close again. It needs to be turned 90 degrees from fully off. I had a puzzling problem with shut-downs and stalling after high spreed runs, and the problem was a partly-open petcock.

[ben2go]

Check the tank petcock and make sure it is turned on completely.Then bypass the frame petcock and see it's better.If it is,then the frame petcock is bad.Make sure the vacuum line from the carb to the petcock is in good condition and connected.

[KatCycle]

My vacuum line is connected and in good condition, I'll check out the tank petcock. If all else fails I'll just rejet and put in pod filters. And my power is just fine in mid and top end to answer gs500e's question. Thanks for the advice guys! You'll probably be hearing more from me later.

-Katlynn