Bike Revs up on Choke but not with Throttle?

[BNR34RB26DETT]

So title pretty much explains it.

75cb550 with velocity stacks and 4 to 1 exhaust.

The bike dies out when i give it gas with throttle. however, when i open up the choke, bike seems to have no problem revving up high.
I have tried this with stock jets as well as jets 4 times larger and same issue on both jet sizes.
What could be causing this choke issue?

 

[Hot500]

When a motor runs better on choke, it usually means you got a big air leak somewhere. Get some carb cleaner and spray it around the rubber intake boots where the carbs join the intake mainifolds with the motor running. Be sure to spray it nice and close to the boots so the spray is not being sucked into the stacks.

If the revs increase there is a big air leak/split/crack/loose conection in the rubber boots.

 

[Flugtechnik]

Is this bike new to you? Are you using the choke right? Your wording confuses me. When the bike is running normally, the choke should be "open" allowing air to pass. You only "close" the choke when you are starting the bike or during initial warmup.

Open means the choke plates are not restricting air.
Closed means they are.

If you try to run your bike with the choke closed, it will bog and will not rev because it is running too rich...not enough air.....choked.

I know this because I was using the choke wrong when I first got my bike. Normally, the choke should always be open. I only need to partially close my choke when the bike is stone cold and then only for about 10 seconds.

 

[BNR34RB26DETT]

When a motor runs better on choke, it usually means you got a big air leak somewhere. Get some carb cleaner and spray it around the rubber intake boots where the carbs join the intake mainifolds with the motor running. Be sure to spray it nice and close to the boots so the spray is not being sucked into the stacks.

If the revs increase there is a big air leak/split/crack/loose conection in the rubber boots.

hmmm ok i will see if there is any kind of leak. i highly doubt it thought because bike was running fine before i took out the air box and exhaust...

 

[BNR34RB26DETT]

Is this bike new to you? Are you using the choke right? Your wording confuses me. When the bike is running normally, the choke should be "open" allowing air to pass. You only "close" the choke when you are starting the bike or during initial warmup.

Open means the choke plates are not restricting air.
Closed means they are.

If you try to run your bike with the choke closed, it will bog and will not rev because it is running too rich...not enough air.....choked.

I know this because I was using the choke wrong when I first got my bike. Normally, the choke should always be open. I only need to partially close my choke when the bike is stone cold and then only for about 10 seconds.

sorry for the confusion. i mean bike revs up if i start the bike with choke open all the way. However, if i close up choke and use throtte, it tends to die out.

 

[SONICJK]

hmmm ok i will see if there is any kind of leak. i highly doubt it thought because bike was running fine before i took out the air box and exhaust...

What did you replace the airbox with?
Seems like we may have just found your problem

 

[coyote13]

He said velocity stacks....I'd bet that's the problem right there.

And I believe used jets 4 sizes bigger, not 4 times bigger.

 

[BNR34RB26DETT]

He said velocity stacks....I'd bet that's the problem right there.

And I believe used jets 4 sizes bigger, not 4 times bigger.

yes, it was 4 sizes larger.
but same effect whether its 4 sizes larger or stock jet size.

https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRhGLVM7WW2b57DW0UeVNlrjEBlIYi6pd7-O92nB4yhMz5BUy667Q
whats shown in CR is the choke im talking about

 

[BNR34RB26DETT]

Any more inputs on the bike shutting off situation?

 

[BNR34RB26DETT]

bumping