Still air box on a performance 2 stroke

[john durrill]

sachsmx,
 Would you have a rule of thumb on what the symptom would be for too large a still air chamber and conversely too small a chamber?
 That would help a lot when trying one from scratch. I understand that it would be a lot like building an expansion chamber. You can use some formulas to get one built but then you may have to change some things due to porting and combustion chamber designs , room for the box and air filter placement to get it work the best.
 I would like to repost some of this on Vinduro if the group has no objections. This thread can help a lot of folks gain some understanding of the why and how on air intake designs. It helped me a lot already.
  Mark thanks for taking the time to give us some insight on this.
 John D.

[john durrill]

hrbay,
 We found this on the net and it looks like there is something going on like what you were thinking in the intake tract. We are starting and stopping a column of air  several thousand times a min. Its worth a look.
Mark, Lew, Donnie , Merlin
 Can any one add some insight to this to help with understanding its application for our use?
http://motorcycleinfo.calsci.com/Airboxes.html
 Lew it does explain what happened to the ST1100 i think.
John D.

[hrbay]

John, the later Puch 175/125's used a cone inside the airbox forming a straight bellmouth, not sure if the intent was to act as a ram to boost the resonance at mid rpm, as in this article, or to just keep water out of the carb in crossings. I think there was a little r&d behind it's use. I can take some pics if you would like. George

GC

[john durrill]

George,
 If you have the time yes a picture would be good.
Doing searches on Google has helped some but i get way too many hits with only fragments of what i am looking for. I must not have picked the right phrase or wording to find it. The Vanes Mark is talking about would have to be made up from plastic or metal and inserted in the air boot at a 90 deg bend. Have some way to make it stationary . It must look something like the Air intake on a MIG 15 with out the flare out from front to back.
 Thanks
John D.

[hrbay]

I'll dig an airbox out tomorrow.

GC