I got a chance to work on my air box mods again today. The out come is really good.
It will include main jets, diaphragm springs, needles, drilling a hole in each slide and the addition of two TPI valves in the air box.
The lighter springs in the diaphragms allowed me to open the air box some and put in larger jets. The hole I put in each slide allowed the slide to open quicker along with the lighter springs.
I tried a Jet kit from Dynojet and it didn't work the way I wanted it to. It would have worked fine without air box mods but it didn't work with the mod, the springs in that kit were still too stiff and the slides oscillated up and down but no nearly as bad as the stock springs did when I opened the air box. See when I opened the air box up I didn't have as much vacuum in the airbox so the springs wanted to keep the slides closed. When I say vacuum I mean it is just barely a difference in it and atmospheric pressure.
If some of this is baffling you then read our article about CV Carbs.
The point is with a stock Teryx with the exhaust tip out, a aftermarket CDI on there and this air box mod we went from 27 peak hp to 33 peak hp. and even a bigger jump in the 15 to 25 mph range.
If this is as far as you want to go then this kit is done except ordering all the individual parts from Dynojet since they don't come in kit form like we do it with the air box mods and bundling it with two TPI valves and doing the install video.
Next we will do this all over again with a exhaust system on there, which should just require bigger main jets.
Then we add cams and do it once more.