Yamaha 40/30 baubbles when throttle turned on

[bforsythe1]

My 2006 40/30 jet stutters and can even die if I crack the throttle full on, if I roll the throttle on its fine. just started doing this over last couple months. otherwise performs great.

[boscoe99]

Is this really an F40TLR model?

If so, have you checked the accelerator pump and nozzle? The nozzle outlet is a nanomillimeter opening in size and is prone to becoming clogged. If you open the throttle quickly you have too much air for the amount of fuel being provided and it will bog down.

[bforsythe1]

This is actually a f40MJH- and I converted it to automatic start-It has a tiller.
I have the factory shop manual and I don't see accelerator pump in there but I have had these carbs apart several times and I assume the accelerator is one of those micro holes going into the throttle body. What is the best way to clean them if the hole is tiny. I know they warn against using fine wire on jets because it can distort the opening.

[boscoe99]

Best way to clean the carburetor is to thoroughly dismantle it. Then, clean it in a heated ultrasonic cleaner using Yamaha carburetor cleaner.

Blow all of the passageways of any debris that might reside within. Using a piece of soft copper wire to rod out the passageways should not hurt the carburetor itself.

Look at the inlet to the carburetor with the air box removed? Do you see a brass tube that runs horizontally? That is the tube from which fuel from the accelerator pump sprays into the carburetor venturi. The hole is on the back side so it can't be seen from the front. Incredibly tiny. If the accelerator pump works you should be able to see fuel sprayed from that tube when the throttle arm on the carburetor is rapidly moved.

[bforsythe1]

baubling 40/30 jet

Thank you so much senior member boscoe-that may save me pulling apart all three carbs. Two questions
1. How do you know so much about yamahas
2. When I put this engine together after it went down the Klamath river in a flood, I never calibrated the vacuum on the three carbs with a gauge because I didn't have one- it ran so well I didn't worry about it. What is the downside of not calibrating the vacuum on the three carbs-I could build a gauge .