hi im new to this forum and am looking for some advise on aftermarket air filter and jets. i have a kfx 400 and im going to add a k&n air filter with dynojet jets. i was wondering if anyone out there has done this and if they had any problems with this combination. and if there were any problems with adjusting the carb afterwards. i will probably run with the cover off the box. if anyone has used this comination was the performance worth the cost.any help would be greatly appreciated thanks

 

I highly recommend the EHS Racing airbox lid, rather than just running with a wide open lid. It has an Outerwears cover that will at least catch the big stuff.

As for the K&N, they will pass dirt! I ran them for a while and every time I changed filters I would wipe out he intake tract, and there was always a thing film of dirt. Why risk your engine for a marginal increase in performance???????

Instead, I suggest the ProDesign adapter with their foam filter (made by UNI). It's a great setup and gives great airflow.

If you are going to do the airbox, you should also do the exhaust if you haven't already........

I has someone do the jetting. I hear that this motor is kind or tricky to jet properly.

 

I just got a z-400 last week. I putting a Pro-design uni filter and a slip on exhaust. I too say put something inplace of the lid . On my 450r I used an old pair of pantie hose slipped over the hole I cut out of the lid. On the 400 I ordered a Outwears lid cover.http://outerwears.com/products.taf?_...87DC0545A25A0F

I would forget the Dyno jet kits!! Your wasting your money. Just go to the parts counter and ask for a 155,160 0r a 165 OEM jet. From all my research I've done in the last few weeks thats all that needs to be upgraded is the main jet. The stock needle and pilot is perfect.

I know Recon doesent like K&N but I have one on my 450R for almost a year and check it way to often. I have found nothing geting past it. I do run a cover over the lid and a outwears over the filter and use the billett ring from Pro design. I personaly think that half the problem people have with K&n is the way they mount them to their flimisly stock rubber boot that colappases and lets dirt in. I am going with UNI on the z-400.[img]i/expressions/face-icon-small-happy.gif[/img]

 

hey guys thanks for the advise. i am putting the filter attachment and an outterwares over the filter. im sorry for not clarifying on that. for the time being i am going to leave the lid on untill i can get a filter for the top of the box.or something less restrictive. as far and the jets im not sure which main would be the best.at this time i wont be putting a aftermarket pipe on it. but that could change as quick as tomorrow. ( if you know what i mean!) im not looking to have the fastest thing out there but something thats got a little more pep. so out of the three jets which one would be the best power gain though out the whole powerband. i just dont want to get a gain out of the top end and hurt the midrange or vice versa. thanks alot