Hey guys,

Replaced the carbs on the bike and have all four cylinders firing again. Took her out WITHOUT the ram air ducts installed and performance was okay. A little sluggish when you first get on the gas, but not terrible. I decided to add the large ducts running into the airbox thinking that would improve airflow and help with the overall performance.

Just the opposite. The bike immediately started sputtering and hesitating as I pulled out of the cove, like it's starving for fuel. I barely made it around the block. Pulled the ducts back off and fueling/performance went back to where it was before. The current setup is:
2000 F4 with 9000 miles.
K&N filter with two brothers slip-on.
Main jets are 132 on outside and 135 on inside cylinders.
mixture screws are 2.5 turns out.

The hesitation was immediate once I added the ducts. All the hoses for the air solenoid and airbox are connected. Do I have a mixture problem in the carbs or am I now forcing too much air into them. Haven't tested the solenoid yet. From reading other posts I seems like guys have gotten away with running the F4 without the ducts.

What am I missing?

Thanks a ton,

Mike
www.performance-paint.net

 

carb sync ............

 

That makes sense. The carbs I replaced my old set with looked clean as a whistle on the inside. They may have been taken completely apart when cleaned.

Thanks

 

Okay, synced the carbs this afternoon. Number two was way off. Performance is much better, but I'm still getting some hesitation after I put on the air ducts. Not as bad as before, but still there.

Could this be a possible vacuum leak or a fueling issue?

I had a make-shift full bottle attached to the airbox when I tested the bike after the carbs. I noticed a few air bubbles coming up into the bottle when the bike was sitting still and idling. I'm guessing I am sucking air from somewhere, interfering with the flow.