k and n air filter on a zx9?

Question

i put a k and n air filter on my 1998 zx9 and its goin like s**t now it is very splutry and wont wind out i left it with a friend of mine 2 see could he fix it its a bit better now but still not rite he said it needs 2 be jetted did anyone hav this problem before and how did u fix it ???????? it has a micron pipe as well

Answer 1

This is a normal reaction to a K&N filter, and a pipe. Best, cheapest, easiest fix it to get a dozen or so small flat washers, 1/8" ID, and a set of main jets, two sizes up from the stock jets. Take the tops off the carbs, remove the needle, and put 3 of the washers on the needle, to lift it up in the slide. Reassemble carefully. Remove the float bowls, install the larger mains. This should clear things up nicely. If mid range is still a bit off, add a washer. If you can, do a top end run, and a plug check. If plugs are lean, go up another main jet size.

Tomcotexas.

Answer 2

I had a 1999 zx9 and fitted a K&N and a race pipe without rejetting and rode it on both road and track for 3 years with no problems. After making these mods it is better to have your bike dinojetted to get the maximum performance gain but not absolutley essential.Double check the filter is fitted correctly and that there are no wires or hoses accidently knocked off or kinked.The filter and pipe mod could create a flat spot in the rev range somewhere between tickover and 4000rpm, but definatly not a total lack of power.Try putting the old exhaust back on and see if the problem dissapears. PS the 98 and 99 are mechanicaly identical.

Answer 3

I'm guessing your bike is carburated, so I'll answer the question like that. If you only added a K&N air filter, was it the pod styly or just the factory replacement air filter? If it was the factory replacement filter, you shouldn't have any issues. The only issue I can think of is at the low end of the RPM range where you might be a bit lean, but I'm not certain just the stock replacement filter would be the cause of that. If it's the pod style air filter this could cause too much air getting into the fuel mixture and you'd be running lean. Check the the fuel mixture screws on your carbs to make sure they're at the correct position. If they have a cap over them then my guess is that isn't the problem. Also a good cleaning of the carbs won't hurt (Sea Foam I hear does wonders for carbs).

Answer 4

You need to rejet the carbs. Installing a low restriction air filter such as a K&N will allow more air to flow into the carbs/cylinders. As such, the air/fuel mixture has been leaned out.
Re-jetting carbs is not that difficult, however, considering you were unaware that this would result from installing the K&N, it would probably be a good idea to take the bike to an experienced professional.
And JD, for the record, power commanders are for FI bikes. The 98 ZX-9 is carburetted.

Answer 5

Put the stock filter back in.
If it runs properly, then the carbs need to be jetted for the K&N
Contact me for a carb troubleshooting guide.
It will explain what to change/adjust to repair different running problems.

Answer 6

yuppers!! whenever you change the pipe or go to a high volume air cleaner it makes the bike run leaner. This can lead to overheating, poor running like hesitation etc. You just need to rejet the carb(s) to run richer.

Answer 7

shouldnt have changed it that much to the bad side.... ive used k&n filters on my bikes with great luck... a rejeting should help you get more out of it.. but i would want to recheck what you have done so far. like maybe replacing what you did to check

Answer 8

pipe and filter will make it run lean, you should either get on a dyno or get a power commander they will both sort out the fuelling and ignition.

Answer 9

take it to dealer or good bike workshop and let them re-jet and service it