Airflow

[MotoRandy123]

The intake tube is 22mm and it goes through a long tube to the front of the seat.

The exhaust is 29mm. That's a bit funny as usually the exhaust is a little smaller than
the intake. I wonder if you opened up a 1" hole in the airbox if she might "wake up" a bit?

There's a little rubber elbow inside the airbox too. I imagine it's for noise but can't be helping airflow...

[old geezer]

This is not a Yager but this was the problem on my People S 250.

http://www.kymcoforum.com/index.php?topic=6701.0

[MotoRandy123]

Did you notice any performance improvements?

I was originally checking the intake and exhaust size to compare to 125 and 150cc sizes, I
wanted to see if they changed them or not. The elbow is most likely for noise. They have
to meet 80db pass by specs.

Yours had a cone, that could be to speed up the air and increase local pressure. If yours has
 a carb there could have been a problem with lag. The pressure drops when you open the
throttle rapidly and leans out the mixture. It might run better with the restriction! I've seen
restrictions in the exhaust, that helps torque.

My last bike was a BMW F650GS, on the early bikes (2000-2004) they had a smaller head pipe
and the motor had a very small rev range (2000-3000 RPM). They increased the exhaust header
size by 1mm and it changed the bike. The new bike had a 4000-5000 RPM rev range!

[MotoRandy123]

I went to my local dealer today and measured a 125 and 250 and by golly they do use different
sizes on the exhaust. They are close but 2 mm larger and smaller than the next size bike.

I wondered if they were starving for air so had a bit more power hiding inside...

[old geezer]

Did you notice any performance improvements?

I was originally checking the intake and exhaust size to compare to 125 and 150cc sizes, I
wanted to see if they changed them or not. The elbow is most likely for noise. They have
to meet 80db pass by specs.

Yours had a cone, that could be to speed up the air and increase local pressure. If yours has
 a carb there could have been a problem with lag. The pressure drops when you open the
throttle rapidly and leans out the mixture. It might run better with the restriction! I've seen
restrictions in the exhaust, that helps torque.

My last bike was a BMW F650GS, on the early bikes (2000-2004) they had a smaller head pipe
and the motor had a very small rev range (2000-3000 RPM). They increased the exhaust header
size by 1mm and it changed the bike. The new bike had a 4000-5000 RPM rev range!

I believe the cone is for noise suppression as it is louder with out it but not by much. It would do no good to speed up the air on that side of the filter. The air volicity  would have to be increased where it mixes with the fuel and is atomized to show any gains.

I believe it runs better with out the restriction. there is NO hesitation through out the rpm range.

[MotoRandy123]

Oh ya, your right, that's feeding into the airbox.

I have no idea why they would do that. All the noise
suppressors I've seen make a 90 degree bend...