More K&N fun

I’m still trying to get the K&N to work at low RPMs because I’ve tasted the increase in performance at high RPMs and I liked it. I first tried cutting the yogurt cup down by about half an inch, since this reduced the diameter of the lip it reduced the height of the cup inside the cone tremendously. Before the lip of the cup was resting on the pleats and the bottom of the cup was flush with the opening of the cone. With the cup cut so the outside diameter of the lip was exactly the same as the inside diameter of the bottom of the cone the bottom of the cup sat about 3″ below the opening of the cone.

Stock yogurt cup

Trimmed yogurt cup

Bottom of cup is now 3″ below opening of cone.

Unfortunately this really made no difference in the running of the engine. It’s still too lean and popping. More popping than the full-size yogurt cup, but not as bad as the straight K&N filter. This got me to looking at the carbs, I try to avoid them as I don’t really speak french, but perhaps I need to start monkeying with the pilot set screws. While looking at them I notice that they have 3 spacers instead of the usual 1 for some reason???

Extra spacers? Why?

In an earlier post I uploaded an MP3 of my exhaust with the K&N. Today I also recorded and mp3 of the exhaust with the OEM air filter.

Exhaust with OEM filter.
Starts at idle, then 2K rpm, 3K rpm, 4Krpm with some difficulty keeping a steady rpm, and up to 5K rpm. No popping or backfiring. A final rev straight to 8K rpm.

Exhaust note with K&N and yogurt cup installed.
The beginning of the file is at 2K rpm, the next step up is 3K, then up to 4K where you can begin to hear popping all the way up to 5K. The rev after that went straight to 8K with no resistance.

One thought on “More K&N fun”

  1. Hi, I just got a 92 nighthawk and have been considering my performance options. I am not an expert by any streach of the imagination. But everything I have read leads me to your only option is to re-jet the carbs. I was considering loosing the airbox and going to pods, mainly because they look cool. However I since found out that somehow the cv carbs reqire vacume from the airbox to work correctly, so pods only on slide carbs. Also exhaust mods or better flowing pipes/mufflers will require a re-jet. I don’t know how long it takes your to warm up but mine is jetted so lean that I usually give up on waiting and just ride away on half choke. I after a mile or so let the choke out but still that gives me an indication as to how lean they come from the factory and how intollerant they would be to any mods that would lean the mixture out further. Anyway, I don’t see the point in using yogurt cups to restrict the flow of the K&N down to the capacity of a stock filter. BTW if I misspelled anything, I’m really not stupid; just a poor speller.

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