F650 Airbox and Filter FAQ

compiled & edited by Kristian #562
Please read the Disclaimer before attempting any work in this FAQ.
Last Updated: 30 December 2006, by Winter #1935

For other related FAQs:


The Airbox and airfilter are important parts of your bike. Clean air improves the combustion process, and the airbox helps reduce the noise from the engine. Keeping your filter in good condition helps with the combustion process, and checking the airbox can help identify problems with the bike (such as too much oil).

The other thing to keep in mind with the airbox, is this provides the air intake into engine. This is important when going through water. If the water is below the air intake, in theory you can cross it. The intake location on the GS/Dakar is much higher than the Classic models.

Filter Cleaning

Cleaning Alternative 1

by Kristian #562, 15/10/01


  1. Remove the Seat.
  2. Remove the LHS Body Panel (2 Allen Key Bolts), 1 Pull-out Plastic Nipple in a Rubber Grommet
  3. To the rear of the battery, just forward of the Exhaust Crossover and beside the LHS rear of the Airbox there is a 2" wide by 5" high Plastic Plate held in Place by two Small Bolts which fix into the Airbox. It looks like this: Air Filter Location The Bolts have about 8mm Heads. The Plastic Plate also has some "Electrical Stuff" attached to it, that looks like a short cylinder. (Flash knows exactly what it is, but I believe it's a solenoid).
  4. Undo both the Bolts and using the attached Wires as a Hinge, gently bend the Plastic Plate (With Wires attached) to the left, toward the battery.
  5. Behind this Panel is the Air Filter, which sits in a groove and just slides out. Air Filter Exposed Wear cotton gloves, it is sticky!
  6. Make sure you note which way UP the filter goes as at the RH end there is a non-symmetric curve.


  1. Remove the Air Filter from its Plastic Frame (Yes you can prise it apart). Air Filter Removed
  2. EITHER, using petrol or bike cleaning agent soak the Filter for 5 mins then squeeze and repeat. Rinse the Filter several times with water until it runs clear and there is no sticky feeling left.
  3. OR soak overnight in a tub of Washing Powder and then rinse the Filter several times with water until it runs clear and there is no sticky feeling left.
  4. If you have a can of spray on filter oil spray it one to cover all surfaces and then put filter in a Zip-Lock Bag and work the oil through. Squeeze out any excess and reinsert in Frame.
  5. Otherwise put the Filter in a Zip-Loc bag with about 1/4 cup of Filter Oil and work the oil through thoroughly. Squeeze out any excess and reinsert in Frame. Make sure the holes match up, don't put new holes in the Filter.
  6. Installation is Reverse and be careful you don't tighten the bolts too much. It's Plastic. That's it. Easy & Cheap!

Cleaning Alternative 2

by Flash #412

  1. This is the diagram to consult.
  2. Remove the two screws and pull off the left sidecover. The solenoid is not in the diagram (to the right of the battery). It is attached to the cover and can be left in place.
  3. Remove the screws that hold the cover, number 4 in the picture.
  4. Pull the filter assembly out. 5 and 6 can be popped apart.
  5. Remove the foam. Clean the foam in detergent and warm water.
  6. Unless someone has used the other kind of filter oil, that should clean it.
  7. If it doesn't immediately work, try mineral spirits.
  8. After you get it all clean and rinsed, let it dry completely.
  9. Get some water-washable filter oil and follow the directions.
  10. Let the oil "set" completely. Reassemble in reverse order.
  11. It is pretty obvious how the foam goes back in the rack.
  12. And the assembly only goes back in the housing one way.

Aftermarket Air Filters

compiled & edited by Kristian #562
edited by Nick # 1085

K&N Filters

K&N Part Numbers
Item Classic BMW F650 US F650GS/Dakar
Stage 2 Jet Kit 81-9326 N/A
Oil Filter KN-151
Air Filter NM SQ-2875
FactoryPro on K&N Filters
Hi Kristian, 
> Kristian  wrote:
> Hi.
> 1. Do you have any feedback from anyone about the size of Factory
> Jets people have used with a Staintune Pipe and Standard 
> K&N Filters and the needle clip location?

Pretty much, no. We get virtually no feedback, complaining, praise,
brickbats, etc.... from F650 guys. I have to assume that all is well
with jet kit / F650!! 

> 3. How much is the Factory Jet Kit for the BMW F650 1996 Model and
> what assortment jets/needles does it contain?

There's pilot jets, needles and a selection of main jets. I don't know, off the 
top of my heard, exactly which jets are included. We do have more jets for sale 
for a larger spread if you think you might need them. Cost: $79.95 Shipping to 
Hong Kong: $20

> 4. Some people reckon the K&N Air filters let too much crud through
and the valves are shot pretty quickly. What filter do you recommend with
this kit?

Umm, at the risk of sounding pessimistic, an oiled foam filter filters really
well. If I was using my bike in a dusty area, I'd not use a cotton gauze
filter..... But, I'd expect that there's not much dusty wilderness left in
Hong Kong? What usually happens is that the valve seats get 
carboned up.... Silt in the engine, I'd worry about rings....



> Thanks & Rgds
> Kristian

Marc Salvisberg email: factory2@ix.netcom.com
Factory Pro Tuning http://www.factorypro.com/home.html
Factory Pro Dynamometer http://www.factorypro.com/dyno/indexdy.html


Twin Air Filters


Twin Air Opinions

F650GS OEM Filter


When I get a New Foam Filter, do I need to Oil it?

What is the Air box drain tube for?

How does the oil from an overfilled oil tank get into the airbox?

What route does it take?

Under what circumstances does the oil actually get down the breather pipe/s into the airbox?

How do I check if the breather is getting submerged.


How does Fuel get into the Airbox?

Normally there are two areas to look at and both are in the Carbs, for which you will need to refer to the following FAQs.

  1. The Flat Valve O-Rings. See the Pukin' Petrol FAQ.
  2. The Float Cut-off Valves. See the Carb Clean FAQ


What are those 2 hoses on the Bottom of the Airbox?

by Dlearl#476 & Bob#550

Both of these hoses are BETWEEN the air filter and the carbs.

Refer also the Canisterectomy FAQ.

Will an aftermarket filter improve performance?

Do I need to re-tune / re-jet my Classic F650 with a new UNI foam filter?

Are there any alternatives to air filter oil?