Air breather substitute for 340 Invader

[Scottyboy]

Is anyone using after market air breathers instead of the stock air boxes. I understand you can put on a K&N filter instead. Any recommendations?

[Tory944]

   No K & N Filters if you are running stock powerjet/econojet Mikuni carbs.  The fuel metering systems needs some vacuum (airbox) to be effective.  If you run standard main jets you are fine to use pods, k & n's or velocity stacks...   you will just need to re-jet "richer".  I don't think my 79' 340 used the econojet carbs.  Someone else on here will have to confirm what type of carbs the 340 used.   The econojet setup used two jets that shared the responsibility for top end fuel metering.  The standard Mikuni carbs used on the main jet to deliver fuel on top.

[Joel]

From the factory it would have been the 32mm Econo-jet carb. Joel

[rminier]

Pretty sure the 340 Invader came from the factory with standard Mikuni's...the 440 Intruder and 440 Invader had Power "Econo" jet carbs. It seems most everyone (from a variety of brands using the Power Jet carbs) discourage removing the stock airbox. Regular Mikuni's often can be used with pod type filters....just jet BIG (compared to stock jets) and start RICH and move down from there. Pod type filters will typically allow more air flow than stock airboxes.

[Tory944]

  So Scotty...  to answer your question, find out if your carbs are standard Mikunis or Econojet Style and then you will know what direction to go.  Hope all this info was helpful!

[kawhead]

std 340 vader carb is the 32 std mik....power jet carbs need the vacuum from the airbox to work correctly....imo the std airbox will not restict a 340

[rickbmac]

As I also have a 79 340 Invader...  Is the answer that I wil need to change the jets if I plan to omit the  airbox?  The specs say that the 440 has the 36mm econo-jet Mikunis and the 340 has std 32mm Mikunis

[Tory944]

Yes, I would start with main jets two sizes richer than stock if you are going to pull the box.  You can always jet down (lean) if your plug readings show over rich.  You want to see chocolate brown to light tan.  I like "mocha" myself.

[rickbmac]

Thanks,

Purchased the sled yesterday. It is my first Kawasaki and I have not been working on 2strokes that long and all I have worked on are fans.  I do know that I need to make sure engine is not running to lean.

Have seen others running without airbox, but not all.  If the airbox should stay...  I will not chance it if the changes will not increase power or decrease weight.

[Tory944]

IMO leave the air box on...   no power improvement (to speak of) on that motor.  Also, don't forget you will need to increase your pilot jets.  I pulled the air box on my 82' Liquifire running "open" velocity stacks and had to increase my pilots from 40's to 47.5's.  You change one thing...  it effects many others...   just like building an engine for a drag car.  Torque converter changes, gear changes, etc. 

As a side note...  the Liquifire engine is not stock, so air box removal was beneficial in that case.  Running larger carbs, high compression heads...  you get the idea.  Good luck!       Tory

[Lloyd (ljm)]

 Tory

 Are you running Invader heads on your Liquifire?  Shaved or stock?

[Tory944]

Invader heads milled and reworked squish (not just shaved).   38mm mics, gearing change and Sportfire helix.  180 psi (w/Klotz octane booster).  Big bottom end performance improvement.

[Tory944]

Stock porting (I just smoothed out the port casting flaws).

[Lloyd (ljm)]

What are you running for a clutch?  Stock HSR ignition and timing?

[Tory944]

TR800...   stock electronics...   advance timing 2-3 deg.