K&N air filter causing worse low end performance?

Question

So I'm still trying to figure out what's wrong with the low end power on my 99 Honda CBR 600 F4. It's prone to stalling and doesn't generate enough power to pull away from a stop unless I add far too much gas and dance with the clutch.

The previous owner slapped a slip on and K&N air filter on there. The slip on makers claim that their product won't really change any performance issues on the bike except make it a lot louder and maybe add 2-3 HP on the top end (I don't really care about that...I hardly use the top end anyway).

Is it possible the filter is doing something like letting in air too easily at the low end? I'm not very well versed on how carbs work, but it seems possible that the pilot jet etc is set up to expect a certain amount of air but wouldn't be able to keep up with more. Maybe I'm crazy, but I'm thinking of shelling out some $ for the OEM air filter to see if that helps matters...worth a try?

Thanks for the good answers guys. I'm putting in an OEM air filter tomorrow to see if that pulls things back into whack.

I have a jet kit, but getting it installed and dyno'd is a real PITA, and like I said, I don't really need the extra bit of power on the top end.

If the OEM filter fixes things look for a jet kit and a K&N filter on eBay...

Answer 1

very possible but I doubt it but like you say buy a regular filter and find out for yourself.

Answer 2

On a stock bike off the showroom, the air/fuel system is carefully balanced by the engineers who designed the bike. ANY change upsets this balance. The slip on muffler and K&N filter certainly do a job of it. My advice does not agree exactly with most of what you read here, but is derived from several years experience, with many bikes. It has two big advantages over what the others are telling you. It is inexpensive, and it works. First, the reason it works, many jet kits mainly dump extra fuel, out of proportion to what a street bike needs. The metering needle taper does not match the factory taper. So, the more air you pull, the richer the mix is, which is not what the engine wants, it wants fuel in the correct proportion to the air. So, to get this, all you want to do is to raise your stock needles slightly. Remove the carbs, remove the top,over the diagraphm, remove the metering needle. Go to a hardware store, get a dozen very small washers, which will just fit the needle. You use these to shim the needle upwards, to let in more fuel, but in the correct proportion. In the good old days, needles had 5 grooves on top, and a clip so you could do the same thing. Use 2 washers on each needle to start, just under the head of the needle. Depending on how open your slipon is, go up 1 or 2 jet sizes. Clean, or put in a new set of plugs, and ride a while. Look at the plugs, if whiteish, use the 3rd washer on each needle, if black, remove 1. If you can make a top end run, you can do a proper plug check. Now, if this is too much for you, instead of a Dyno_Jet kit, get a Factory kit. Much better job of engineering than Dyno Jet, FOLLOW INSTRUCTIONS TO THE LETTER.

If you have questions, or doubts about this, you may E-mail me, I will answer any questions you have and provide any info you require.

Tomcotexas

[e-mail]

Answer 3

The oiled gauze air filter is nothing new, they were fitting them to production cars in the fifties as standard . I don't know why paper elements became so widespread, but it certainly created a market for paper filters that had to be thrown away every few thousand miles. They were cleaned in petrol and reoiled quite easily . They do work quite well increasing the air rate in the induction system. The downside that I found with mine was that it was impossible to connect the warm air intake system to it so more petrol was wasted on short journeys with the engine taking longer to warm up.

Answer 4

A K&N is designed to deliver 20%-40% more airflow. If you just slap one on a engine with out re-jetting the carb or re-mapping the EFI you will have problems and a shortened engine life from the extra heat.

I would either do the mods or go back to stock.

Answer 5

u need it rejetted for the air cleaner. it's runnin a tad too lean by the sounds of it. the best way to go is having it dyno'ed. they can dial it in razor sharp and u'd swear it was a brand new bike.

it really sounds like u desparately need a rejet; the ex-owner did a half azzed job in doing a stage 1. u have a free flowing air breather and pipe...but he didnt do jack with the carbs. there's yer problem. and if that slip on was actually a straight pipe, u'll lose low end torque, and for the engine to wake up, u'll need it 4k rpm and higher.

Answer 6

hi, i am pretty sure your problems come down to thre filter, go back to original and i think it will be ok, your engine is probably running very weak, pull a plug and if its really light brown youve got the answer, or there used to be a product called colortune which is a glass spark plug, it shows the mixture when the bike is running, it should burn with a pale blue flame, but anyway i am sure its the filter. regards steve

Answer 7

Install a jet kit.
It's pre-calibrated to your bike with the upgrades you've added.
http://www.powersportrider.com/CGI-BIN/ZCATJPG?catpub=ST0206C
Pick - Street Catalog
Got to - Index - DYNOJET
Or contact me for a carb troubleshooting guide.
Carb jetting can be a tiresome, time consuming and expensive endeavor.
Spend the money and purchase a jet kit.

Answer 8

I'm not that familiar with crouch rockets but it sounds to me that has to much air flow and not enough fuel. pull a spark plug out and look at the electode. if its white or very light cream color you running to lean. if that's the case get a jet kit or have your efi adjusted by a dealer witch ever one you have.

Answer 9

Get it set up by a prof. Dyno jetted is pretty much a must in conjunction with K&N. You are sat on a shite load of fun!!!
I dunno what a slip on is. but if it's an exhaust you should be doink ok. it's just the set up.
It's gutting but when you get this kiddy running FOUL it'll be worth the tuning money.
Good luck.
Go fast!

Answer 10

The OEM stock should get it back to running normal.Right now it is running too lean with the K&N intake.It needs to be rejetted properly.