under hard throttle sounds like a rev limiter

[Michael woods]

I have a 81 GL1100 I fully restored this bike that's the one that I've been working on for the past 6 months now I got it on the road and as long as you accelerate normally it'll go through the gears it'll go through the RPM range just fine smooth this silk. But if I get on it 3/4 throttle or more as soon as you hit 4500 to 5,000 RPM it's like it has a rev limiter even sounds like it has a rev limiter and it will not accelerate any further unless I let off the throttle a bit. I rebuilt the original carbs and done it with those went through them two or three times, so I bought a set of 83 carbs from Phillip Dan's he knows the carburetors well. I rebuilt these carburetors they are tip top perfect shape I have been rebuilding carburetors for a very long time so I know it is not the carburetors. Compression good on all cylinders 150 to 155 great spark but I do not know what is causing this problem has anyone ever had this kind of problem with their GL1100 I'm wondering if it has something to do with the pulse generator please any help would be fantastic . Things I know it was not it is not the carburetors two sets same problem it is not the valves compression good no problem there. It almost acts like it is starving for fuel has plenty of fuel flow though. This bike has had all I repeat all required maintenance done required to bring an old wing back to life head gaskets water pump belts valves lapped carbs rebuilt synced two different sets

[Rambozo]

Sounds like a weak fuel pump. Put a pressure gauge on it and go for a ride.

[Michael woods]

What should it be running?

[Rambozo]

A couple of pounds. Just make sure when you open the throttle the pressure doesn't fall.

[WingAdmin]

There's a test you can do to see if it's a fuel pump.

Accelerate hard until the engine starts to bog down, then twist the throttle to idle for a few seconds, then open it up again. If the fuel pump is struggling, it will start to refill the carb float chambers when you let off the throttle, and once you get back on the throttle you will have power again (until it runs out of fuel reserve in the float chambers again).

But you said it sounds like it's hitting a rev limiter, which to me sounds like spark.

If it's fuel, the bike will bog down like it's running out of gas. If it's spark, it will jitter like it's hitting a rev limiter.

Under hard acceleration, you need more power to generate spark, so if any part of your ignition system (coils, wires, plugs) is weak, it will lose power under heavy acceleration.

[Michael woods]

Yeah I think it might have something to do with spark I'm doing the neon coil upgrade mod on it right now if that doesn't work I want to pull the pulse generator off and see if maybe the spark advancer is not moving the mechanical one

[Michael woods]

So my problem showed finally I'm running rich. At full throttle so took the carbs back out put different needle valves in because the springs on the others where fully fatigued set the float to 16mm instead of 15.5 and it helped tremendously. However it is still somewhat there at 5000rpm but you can outrun the studder now. So should I set float height 1/2mm lower or look into different floats im wondering if they are saturating?

[Rambozo]

Do you have brass floats or plastic?
If brass, shake and listen for fuel inside.
If plastic, weigh the floats and compare.
A mm or two of float adjustment is not going to make or break how the motor runs.
How do the plugs look?

[Michael woods]

They are plastic no fuel in them. Like I said I adjusted them to 16mm and it ran a lot better it seems to be only running rich in the 5000 rpm range. Plugs are as they should be light tan. I'm going to adjust them to 16.5mm it just bothers me that the factory settings is supposed to be 15.5 I guess 1mm shouldnt hurt anything. I wish you could lower the needle in these carbs. Bike runs perfect every where accept the 5000 rpm range it stumbles, studders, rich only there