Bonneville America Forums Forums Technical Forums Performance Mods K&N and jetting?

Hi all,

I've got an '05 TBA all stock. I've removed the AI, and I'm thinking of replacing the stock filter with a K&N. One reason is for whatever performance increase I may be able to get. I've been reading a lot on here and have asked a mechanic some about what all I can do for a bit more HP / quicker throttle response, and I've basically learned that I won't get much unless I open up the exhaust. I'm probably not going to take that step. I'll probably make another post about exploring that, but for now, my question has to do with the intake and jetting.

So, am I correct that with stock pipes, I should not open up the intake too much? Is K&N roughly the same as drilling airbox with stock filter or should I also consider drilling with K&N? The jetting calculator doesn't seem to have a selection for a single replacement K&N - am I missing that?

I've been told that I should not have to up the jets (from 120) with just a K&N, but depends on how the bike runs. (Mind you, the bike runs GREAT now, but does seem like it has more get-up-and-go available.) I thought these bikes are lean from the factory, so I'm a bit hesitant about increasing air w/o jetting, and assume I'd see a bump in performance with a slightly larger jet anyway, which is what I'm after.

Bottom line: If I keep stock pipes, what's my likely set-up on the intake and jetting for some noticeable (if minor) performance increase w/o doing damage?

This is a wonderful site - a great resource for newbies. Thanks!

You'll be okay with the stock jets until you change the pipes. Just open the mix screw a little to get some extra fuel at low throttle inputs.

Think of the engine as a air pump...air in (intake changes) has to equal air out (exhaust changes), so with out exhaust change there will be a very minor change in performance to change to K&N filter

you will really not notice to much, in fact you may find that you loose a little bottom end, otherwsie if you are overall happy with the performance then just leave it, making one change is a slippery sloap that will ALWAYS lead to another one. Whats happening is that you are becomming very familiar with your bike and its not like you need more horsepower, its exactly the way it was when you fell in love with it. Drive it and enjoy

At the englishyankee's (Greg) house last month I cleaned then installed his Uni-filter into Prudence. I did not notice a difference. Prudence has TORS too. 40/120 2 turns

Thanks for the replies all. Well, I guess I should ask about whether it would be worth it to remove 1 (maybe 2?) baffles from the pipes to go along with the K & N? I wouldn't mind a deeper sound that would produce but I can't have it be much louder (noise level issues for inspection.) If that wouldn't produce any noticeable difference, then I probably will just stick with everything stock, as suggested by some here.

What was it that edmspeedmaster was saying? Once you start...

That aside, I have to say that having a whisper jet is much more agreeable than having a couple of barking mad girls when trekking cross country! So removing a baffle or two is still fine, just remember that you will need to look at your spark plugs if you do so (to see if you need to re-jet, which you most likely will have to).