Surging/loss of power at high revs, and unable to find steady idle

[jonathanhly]

I believe I have a fuel delivery problem. It is most noticeable when I "attempt" to ride the freeway. Above 60 mph and over 5-6K it begins to surge and lose all power response. Its like it irregularly gets fuel. It will pull, then bog, pull, bog. When I get off the freeway I have to keep on the throttle until I can hear the engine pick up, or else it will stall.

I also cannot seem to set my idle. With the bike warm, I will set it where it idles smoothly, and then at the next red light I'll have hanging idle. I turn it back down and then at the next light it wants to stall.   

I have just cleaned the carbs for the third time, removed the inline fuel filter, and replaced all hoses with tygon.

I haven't checked flow from the tank yet, but it did seem impeded when the filter was inline.
Float height is good. I havent checked for air leaks in a while, but last time it checked out.

I'm actually debating taking it in to a shop...
or maybe sending the carbs to buddah   

[The Buddha]

Acceleration problems are rich.

Pull bog pull bog also rich. Though its very uncommon to get that in a GS - I am not even sure I can get it to if I was trying, but my eliminator did it when I put 160 mains in it ... over the correct 150.

You have a float set waaaaaaay high ?

You may have lean idle but be rich everywhere else ... you seem like you're overflowing floats. That what is getting it to stall @ lights.

Send me the carbs fine - you have it jetted already ? Then $25 and return ship to you.

Cool.
Buddha.

[jonathanhly]

The problem does affect my acceleration, but also constant speed. Again on the highway, I can accelerate to speed and then at some point it will simply lose all power and begin to slow. At one point I had the throttle fully open attempting to stay over 50.

The jetting is stock, in fact the entire bike is stock.
The floats are a tad bit high.
The mixture screws are at about 3 turns out.

However- the plugs, as they always have other than right when I bought the bike, appear to be oxidizing, signaling a lean condition.

For 25 dollars buddah I feel like I'd be stupid not to send them to you.

[jonathanhly]

However another thing signaling running rich is that after a 30 minute ride, I got off for a few minutes maybe 10 tops, and when I got back on it wanted choke to idle. Like I was starting a cold engine.

[jonathanhly]

Well, I have checked a few things off the list.

The float height is spot on. Right at the gasket level using the U-bend method.
Fuel flow from the tank is good.

And I pulled the plugs again after a ride yesterday and if anything the bike is running lean, not rich. The plugs look brand new other than the tips that are beginning to oxidize.

I guess the next thing is to check for air leaks, maybe I have a HUGE one??

[The Buddha]

You wont be reading spot on plugs with anything even a mouse sized vacuum leak, let alone an elephant sized one.

You may have a tiny rip in the diaphragm. Or I dont have any ideas for now.
Cool.
Buddha.

[jonathanhly]

Well, I'm still having the problem. But Ive checked a lot off the list.

Carbs are clean.
Diaphram is not torn.
Jets are not clogged.
Needle appears to be fine.
Float height is perfect.
Carbs are synced
Tested and seemingly found no air leaks.
Carb vent hose is nicely tucked behind air box.
All lines and cables are perfect.

Mixture screw is now at 3 turns out.

[RossLH]

Check the valve clearances?

[jonathanhly]

They should be good. Did that a few months ago.

[oz353]

what do your carb boots look like? can you see metal around the bolt holes?

[jonathanhly]

My carb boots look good as well. I tested for air leaks again today and found nothing. I tucked the carb vent hose into the battery compartment to make damn sure I wasn't getting cross wind.

Im pretty stumped. It has gotten slightly better, most likely because I've been riding in the prime position.

I'm beginning to think it is gear related. 1,2 and 3 can all accept full throttle, as well as consistant 8k rpm. But it seems 4,5 and 6 cant even hold a steady 7k. The engine noise changes. It really sounds like its bogging and is accompanied by zero power, followed by a tendency to want to die.

Could this be gear related? 

[jonathanhly]

Well, I figured it out. My floats were set far too low.

I had been setting them with the U-bend method. Which for some reason in my case, does not supply enough fuel.

So I set them to 14 mm and the problem is fixed.

I know that the 2001 carbs are different. They have completely different float bowls.

Anyone else experience this?