Air Filter Service
DIY WORKSHOP SERIES
ISSUE 39. WORN GRAPHICS - Bring back that new bike feel...
ISSUE 40. WIRING DISASTERS - Tame the wiring harness jungle...
ISSUE 41. BRAKE SERVICE - Start looking after your stoppers...
ISSUE 42. WHEEL BEARINGS - Roll clean, and free...
ISSUE 43. CHAIN & SPROCKET - Tired old teeth slow you down...
ISSUE 44. CONTROL REFRESH - If you can’t put your finger on it...
ISSUE 45. DON’T GET DUSTED - Keep that box clean...
ENGINE AIR FILTER SERVICE GUIDE
Cleaning your bike’s air filter ranks right alongside changing your oil as the most important maintenance task you can do to properly look after your engine. Short of writing off your pride and joy in an accident, the quickest way to destroy a perfectly good machine is an iron lung-full of dust being sucked through your cylinder ... because a full rebuild is a highly likely scenario if you don’t maintain your air filter.
Most modern bikes come standard with high-quality foam filters, but it’s well worth investing in two or three spares. This allows you to keep a rotation going and do all the dirty work in one batch. Old filters can also start to break down over time, so invest in new ones every couple of years.
Filters always get dirty wherever you ride, so get into the habit of checking your filter before each and every ride. Ideally, change the filter between every ride, or at least try to ensure it’s seated correctly and is relatively clean.
Nick Dole from Teknik Motorsport explains how a filter change is properly done.
TOOLS YOU’LL NEED
Spanners, T-bars and Socket Set
WHAT A FILTER CHANGE WILL COST YOU
Labour: 20 minutes
Filter Oil: $25
1. REMOVE THE FILTER
Once you’ve removed the airbox lid – or seat – necessary to access your filter, grab a clean rag and wipe any dirt away from the edge of the filter and from around the airbox. This prevents crap accidentally falling into the air boot when the filter’s out. Then, remove the fastening screw or bracket and pull the filter out.
2. INSPECT THE AIR BOOT
With the foam filter out, grab a torch and have a good look inside the black plastic air boot leading to the throttle body or carby. Wipe your (clean) finger and check for any dust. Even the lightest of coatings may indicate that dirt has bypassed the filter, which could signal trouble for your engine.
3. CLEAN & RINSE THE FILTER
Pull the foam filter off its plastic frame, and soak the filter in a kerosenebased solvent (petrol can deteriorate the foam and glue). Once the oil has broken down after a minute or two, use your fingers to work out any trapped dirt particles from the foam elements. A rinse in warm soapy water will ensure a thorough clean.
4. DRY THE FILTER
Ensure the filter’s dry before oiling. To speed up the process, you can place it on newspaper or paper towel or hang it on a fan, but by far the most efficient way is to hit it with pressurised air. Avoid hot air guns, though, as this can melt or degrade the glue used in the filter’s construction
5. OIL THE FILTER
Air filter oil is seriously sticky stuff, so the cleanest way to oil a filter is to wear gloves to work the oil through the filter, or put the filter in a plastic bag to mush the oil through. Ensure that the oil has passed through all of the foam pores. Aim for an even coverage, but with any excess oil squeezed off – otherwise your bike’s air intake may be unnecessarily restricted.
With the filter cleaned and oiled, reinstall the filter on its plastic frame. it’s a good idea to leave the oil to set for a few hours before re-installing on the bike. now put a generous layer of grease around the airbox seat and the sealing surface of the filter. This will prevent any dust entering around the filter. Ensure the filter is seated neatly and fastened.
Air filter skins are a thin, stockinglike material that is designed to fit snugly over your air filter to act as a kind of pre-filter. The idea is that the skin can be pulled off when dirty, leaving your foam filter largely clean and extending the intervals between filter changes. Skins are cleaned in the same way as filters. They are great for multiday trailrides, but not everyone uses them, as they restrict airflow and require special care to ensure a good seal between the filter and airbox.
Cleaning the Airbox
Over time, your airbox will get a build-up of grease and dirt. Degreaser will help, but the best way to really get your airbox clean is to pull the whole subframe off, together with the airbox, then hit it with a pressure washer. When re-installing the subframe, be particularly careful when fitting the air boot back onto the throttle body or carb – a loose or misaligned boot will suck in unfiltered air and kill your engine.