I checked their website and couldn't find the answer. If so to what?

 

Some people will tell you to avoid the K&N filter like it's an infectious disease, others, who use one, SHOULD tell you: YES, you're fueling will be way off, once you install the filter.
If you choose to install this type of filter, getting a jet kit wouldn't be a bad idea, so you can get the jet needles with a more agressive fueling taper anyway (though, these might be available without getting the kit), but if it's a stage 1 kit, from Factory Pro (my preference) or DynoJet, you might still need larger main jets than what is supplied - my kit came with 138 as the largest size (stock is 135), but I ended up with 142's, to get the top-end set up right - bear in mind, that a setup which works on one particular year and make of bike, might not work on another of the very same.
Just know that you are asking for a headache, since you cannot just drop the filter in place and go - it will require a good amount of work, and you should count on pulling the carbs several times, to get all the fuel circuits right.

 

Thanks for your input, the bike I picked up in January has some carb issues. They are currently pulled and taken apart for cleaning. I noticed the carbs had different sized main jets (3-140 and 1-138), the K & N air filter and a Two Brothers exhaust. The more I investigate the more questions I come up with. I think I'm going to go back to all stock parts. Thanks again.

 

No problem.
You can never go wrong with stock setup, though, in this case, you may still have to tinker a bit to restore the carbs to match an OEM filter again.
Like I said above, stock mains for the F2 are 135 - you can get those for around 4 to 5 bucks a piece from anyone who stocks Keihin round main jets - when you do get a stock air filter back in, you might have to play with the jet needle clip position, to get the mid-range dialed in, since the PO might have changed things to accomodate the filter...speaking of the PO: three 140 size mains and one 138?!? sounds like a big old FAIL to me!!

 

Thanka again.....the local Honda dealer quoted me $9.99 each for the 135 jets (not in stock, they have to order them) and $44.99 for the stock air filter (in stock).

Educate me; where are the "jet needle clips"?

Yeah, I thought the different jet sizes seemed odd too, but what do I know, I'm sort of new to messing with bikes. Many thanks.

 

$9.99 per jet?!? That's HIGH!! I picked up mine at my big local powersports dealer for between $4 and $5...that sucks!!
Anyway, check my ongoing thread for pics of the carb work; I dont' remember how detailed the carb pics were, so if those don't give a good enough indication of the jet needle apparatus, I can get you some more - or, just search the F2 forum for "carb rebuild", or something like that, and you should find plenty of results.

https://cbrforum.com/forum/cbr-600f2...se-1-a-136400/

 

ya local jets at my spot are 6 bucks no tax if cash haha