Voge air filter: cleaning, replacement and intervals

The air filter is the least expensive component on the motorcycle with the greatest influence on how it runs, and the maintenance plan treats it differently from every other item.

The plan alternates cleaning and replacement

Service	1	2	3	4	5	6	7
Air filter element	I	C	R	C	R	C	R

Inspect, clean, replace, clean, replace, clean, replace. It is the only item in the plan that alternates in this way, and the reason is that a paper element can be cleaned once or twice before the fibres pack and cleaning ceases to be effective.

The 300 series engine is treated more strictly. Its service manual calls for the filter to be cleaned every 1,000 km and replaced whenever damaged rather than on a schedule. It is a small engine with a small filter working hard.

What a blocked filter does before it fails

It does not stop the engine. It causes the engine to run rich, because the injection system meters fuel against an airflow it can no longer obtain. A rich engine:

• loses power at the top of the rev range first
• consumes more fuel
• fouls the spark plug, producing the black and sooty plug reading
• shortens the life of the catalyst in the exhaust

The DS900X manual names a dirty air filter as one of only two causes it offers for an engine that has gone flat. The other is altitude, which cannot be remedied. See weak engine power.

Cleaning the element correctly

1. Note its orientation. Filters are directional and fitting one reversed defeats the seal.
2. Tap the loose dust out first, into a bin rather than onto the bench the element is about to be laid on.
3. Blow it through from the clean side outward, at low pressure. Blowing from the dirty side drives the dirt deeper into the element.
4. Hold it up to a light. Where light no longer passes through, cleaning has reached the end of its usefulness and the element is a replacement.
5. Inspect the housing and the intake tract while access is available. Anything present there enters the engine.

A paper element is not washed in water or fuel. It will appear clean and will have lost its structure.

Refitting the housing

The air filter case fasteners carry genuine torque figures on some models: on the 650DSX the cover screws take 2 Nm and the case to throttle body bolts 6 Nm. The figures are small for a reason, the housing being plastic, and an over-tightened screw cracks the boss it threads into, which converts a filter service into a new airbox.

The housing seals are checked against the frame. An air leak downstream of the filter admits unfiltered air directly to the engine, which is a worse condition than a blocked filter.

Where the interval is halved

Dusty routes, gravel roads, dry summers and long commutes behind traffic all load the filter faster than the plan assumes. In those conditions the interval is halved and the element inspected, since the filter is the component that registers where the motorcycle actually goes.

Related pages

The full service schedule is in what Voge asks for at each service, and the plug reading that indicates a rich mixture in spark plugs and electrode gaps.