Do you need to rejet if you put in a K&N air filter?

[warnerwh]

Seems like I read that you will run to lean with one of these filters installed and a rejet is necessary. It's time I actually changed the air filter and found the OEM filter costs almost as much as the K&N. My bike runs perfect and I don't want to mess with it.  If I did a rejet how long does it take for someone who's mechanically inclined? Thanks

[hootmon]

I ran for about 3 years with a K&N and stock pipes and stock jets
I then drilled a fairly large hole in each exhaust end plate and ran that way for a little over a year.

I did also add a shim to each needle about 8 months ago (I did not pull the carbs).

I only very recently upped my jet size from 102 to 105. I do definitely feel an improvement with the new jets (less hesitation and the real power kick I used to feel about 6400 RPM to redline now starts closer to 4000 RPM and runs through redline. I also drilled another large hole in each exhaust.

I've never pulled the carbs on a Magna (Make sure you print out the instructions under tips and tricks) and it probably took me about 3 hours - (It really took me most of the day, but I took lots of breaks, etc).. Some of the experience MOOTsters say they can do it in about an hour. I took the time to clean out the bowls and remove all the idle jets and clean them and re-adjust my pilot jets while I had the carbs out.
The job was not as hard as I thought it would be. I had taken carbs off of a CB1000c before and all things being equal, I'd rather do it to a Magna as the throttle cables are a pain on the inline carbs..

[warnerwh]

So your bike ran fine with just the K&N? Did you notice any difference at all? If so I'll get the K&N. I know rejetting is a actually a very good idea to make the engine run properly. The surging area though doesn't bother me enough to spend the time to rejet. Thank you for the help.

[Cannon]

I've been driving with k&n and otherwise stock bike (3. gen) for 4 years. Did not notice any performance- or other change when I moved to k&n.
Is the k&n supposed to alter performance in any way? I dont think so. The idea is to save money by clean/oil/reuse.
I have now added shims to my needles, and still do not think I need to rejet (but maybe that would improve performance?). The bike runs smoother than ever before  

[warnerwh]

The issue with the K&N is that it will breath much easier than the paper element. These bikes run very lean from the factory and pushing the envelope any more could cause an over lean issue or at least it seems like I've read that before. Probably various parts of my brain are unorganized though. I'm glad you also say you noticed no difference with the K&N. I'd rather get ripped off on the paper filter than pulling the carbs at this point in life. Plus my garage has a ton of stuff in it that shouldn't be in there and no matter what I say or do my wife seems like she really doesn't care.

[Chad in Michigan]

some of us have had trouble with the k&n and had to rejet, so be aware of that before you spend the $$ on the filter. you may notice off the line surging, lurching, not as responsive throttle, etc. this means you need to up your pilot jets one size. stock size is 40, up all of them to 42 and turn your 'd' screws on each carb to about 3 turns out for a starting point. if you go this far, you may even want to add a shim on each needle to help out the midrange flat spot and increase your main jes from size 102 to 105 (if you have stock exausts)

[warnerwh]

Thanks Chad. I thought I'd heard of some problems with the K&N but was beginning to wonder if I had been mistaken. I'll have to get the paper filter just to be safe.