Topic: K&N air filter too restrictive ?!?!

[grumpy]

I got a K&N filter for my OEM airbox (NOT pods) on my 750.
The plugs are now carbon-fouled!
What's the deal? K&Ns are supposed to INCREASE air flow.

Anybody else ever try the OEM-size filter?

[heffay]

very light oil for particle capture... most k&n filters i've seen are waaay over oiled.

[754]

The excess oil should have ran off it.. but just run it up at high rpms a while, it aint gonna come out forever..

 K&N..cant think of a single other product that captured such a large segment of motorcycling poulation..

[HondaMan]

It takes almost no oil to over-oil these filters. I have a 1 quart bottle of K&N oil, and I wash my filter once per 10,000 miles, which makes it 12 times in 30+ years, still have 3/4 of the quart bottle left. And, I've accidentally over-oiled it at that, several times! About 1/2 ounce of oil will do it, but it can be hard to spread that around, except by a brush.

Wash the filter out, let it dry several days, and try lightly brushing about 1/2 to 1 ounce of oil onto the face (outside) of the filter. Let it sit for 2 more days, and you will see much of that oil drain to the bottom and make a mess. Shake that off, and give it a try.

The carbs breathe so much better with a stock airbox (with its own velocity stacks inside) with the K&N fitted that it will let the carbs run richer because of increased efficiency. I ended up dropping a 5 size mainjet while still picking up nearly 2 dyno HP when I first fitted it, in 1973. There's nothing like a full-size K&N in these bikes, for increased breathing. We used to call it "the cheapest port job around". 100% of my roadrace friends ran them in the stock airboxes, always out-dynoing the pod filter guys.   

[crazypj]

When you remove stock airbox it runs real rich mid range, particularly if you jetted it correctly for high rpm/full throttle.
 Easiest thing to do is raise float level to max (or even 0.5mm too high to lower fuel level)and DROP needle at leasa one notch
PJ

[grumpy]

It had occurred to me that it could be over oiled... but it's fresh out of the box.
You'd think they could get the oil correct at the factory!   

[heffay]

i don't believe that they are oiled at all from the factory... i could be wrong though, there's a first time for everything.   

[grumpy]

i don't believe that they are oiled at all from the factory... i could be wrong though, there's a first time for everything.   

Yeah - they come pre-oiled.

[HondaMan]

I think they started oiling them in the box around 1995 or so, at least for cars. And, they are over-oiled pretty badly on the "Filtercharger" units they sell at Checker.

All in all, it runs well once the oil pulls through, which may take a tank or two of gas. Run on lower octance gas, like regular, which will help (today's fuels burn slower, like older premium did). If you are running D8E plugs, try using D7E for a while, especially in colder weather. The D8E are too cold, even on a summer day, for these bikes. The X24ES-U from ND stays cleaner and the extended tip produces a bit more midrange torque by firing off the rich midrange a little further above the head's surface. It has an equivalent heat range to the now-gone D8ES-L plug, which was made expressly for the 750. That plug had an extended tip and a heat range of 7.5 on the same scale. It was the answer to the plug fouling problems these bikes had with the 1970s gas, until it disappeared in the 1990s.

[754]

There should be a pink tinge to the filter when you use factory oil.

[grumpy]

Yep - nice & pink right out of the box.

HM:
Already have the Densos bases on your previous recommendation  ! Do you gap them the same, BTW?

[HondaMan]

Yep - nice & pink right out of the box.

HM:
Already have the Densos bases on your previous recommendation  ! Do you gap them the same, BTW?

Yep, same gap, unless you're running a Dyna 3-ohm coil. Then gap them at .040" or so.