SERVICE INFORMATION & TIPS
How to get the most out of your motorcycle’s engine oil?
Oils are so advanced now that the typical rider won’t see any problems if it’s changed at the recommended intervals. Of course, it depends on how you ride, but unless you’re putting your engine through very extreme stress – for instance by racing – the oil will easily go the distance.
The filter should be changed with the oil – it’s a relatively inexpensive part, and unlike some cars that allow a filter change every other oil change, a motorcycle engine works a lot harder. Some bikes, like certain Austrian and Italian motorcycle manufacturers, have one or more mesh screens fitted to further filter the oil – in this case they can be washed, but a complete kit of filter, O-ring and two mesh strainers costs will not cost the earth and are often a necessary requirement in the manufacturer service schedules.
Many bikes have a ‘canister’ oil-filter, typically mounted at the front or bottom of the engine and easy to access – the disadvantage with these is that they can be easily damaged. We have seen filters that have been punctured by a foreign object such as a stone, which subsequently caused oil to spray over the rear tyre. Some models utilize a cartridge-type filter that’s tucked away inside the engine, making it less prone to damage.
Some bikes – typically more specialist or 'older-design type' machines like the Honda CR450 and Harley's – use a separate oil for the engine and transmission, whereas you’ll usually find your motorcycle takes one oil in the sump to lubricate the engine and integral gearbox. Bike oils are different to car oils as they’re designed to soak the clutch plates – a car oil will cause it to slip.
Even in older Ducati's, which had dry clutches (hence the distinctive rattle sound), a specific motorcycle oil must be used, not least because it needs to deal with the sheering forces of a gearbox, cheap supermarket oils really do not offer value for money when it isn't doing what it is designed to do. Avoid these at all costs, the price is usually a quick giveaway to their quality.
When checking the level of your bike’s oil, consult your owner’s manual first – some machines have a very specific procedure, and checking while the bike’s cold might lead you to believe that the level’s low when it’s not; overfilling an engine can be almost as damaging as starving it of oil.
Why are motorcycle valve clearances are so important?
Checking the valve clearances on your bike is very important, and in most cases is simply a case of setting the engine to a specific crank position, then using a feeler gauge to check the gap between the cam lobe when it’s off its tallest point, and the follower, which is what pushes the valve open; measurements are usually started at TDC (Top Dead Centre), which is where the piston in a chosen cylinder is at its highest point of the compression stroke.
It’s an easy check, but getting to the cams in the first place is a very, very big job in most cases, which is why it’s one of the most expensive service bills on a bike. In the case of many motorcycles, any bodywork has to be stripped before the tank comes off, then the airbox taken out, the radiator swung away and the cylinder head covers removed. This is the most labour intensive service and often the service most often ignored due to larger servicing costs, this is not optional and should be adhered to dependent on your motorcycle model. We often find most bikes are sold when these services are due, service schedules are bodged or assumed and the new owner is left feeling ripped off thinking they had a good deal. Please always check for FULL SERVICE HISTORY and obtain copies of the invoices so you can see what was done on each service, do not assume a fully stamped book means the correct servicing has been done, an annual service every year doesn't mean that the dreaded valve clearance check has been performed does it?
Often, valve clearances on modern quality motorcycles that have been ridden on the road are within tolerance at the first inspection – the manufacturer will give a minimum and maximum gap. By the second inspection they’re more likely to need adjusting – usually with varying thicknesses of small shims that sit under the follower in a ‘bucket’. To do this, the mechanic will note down all the clearances (these are recorded on the service sheet – along with every other maintenance record – from the measurable components), then remove the cams to get to the shims. Each one must be kept in order, so the technician can measure the shim’s thickness with a Vernier caliper, then work out what size shim he or she needs to replace it with to get the correct gap. New shims are measured before fitting into the relevant followers, the cams refitted and the gaps checked again.
Some bikes – a good example being the Honda C90 – use a screw-type adjuster in the tappets that follow the cam. This is a lot simpler, and certainly on a machine like this – which has very easy access to the engine – the cost impact should be minimal.
Whatever system is employed for setting the valve clearances, the measurements have to be taken with the engine absolutely stone cold. Many customers bring their bikes to the workshop on a trailer, as otherwise the mechanic would have had to have waited a very long time to make sure the motor had no heat in it and the customer for that matter!
What happens if I ignore my valve clearances?
When valve clearances do need adjusting, they’re almost always too tight – this is because the valves start to bury themselves into the seats in the head, so the valve’s stem rises, getting closer to the cam. If they go too far, the bike will become harder to start, will backfire on the over-run, and lose power.
Over-tight valve clearances will lead to increased engine wear and damage; the cams will suffer more wear as the followers are in contact with them for longer, the valve seats will become damaged, and the potentially increased running temperature could cause problems in other parts of the engine.
Some wear is normal on the valve – the light polishing seen on a healthy set will likely have happened in the first few minutes of the bike being run, often when it was spun up on the rolling road as it came off the production line.
How can I reduce the wear on my engine’s valves?
In order to keep the valves within their tolerances as long as possible, always use the correct grade of engine oil.
Over-revving your bike too much will also accelerate the wear due to the valve springs resonating. At very high frequencies, they can start to ‘bounce’, which causes them to open the valves without the cam’s timed assistance.
Using the wrong fuel can also have an impact – for most road riders, typical premium unleaded is fine, but some people believe that the higher the octane, the more power their engine will make. This becomes an issue when octane booster additives are put into the tank along with very high-octane fuels (often used in racing or at track days). This combination can run extremely hot, pushing an engine beyond its capabilities.
When do i change my motorcycle brake fluid?
While a racer will need to change their brake fluid far more regularly due to constantly getting it very hot, the average road rider need only stick to the manufacturer’s recommended intervals. Brake fluid is ‘hygroscopic’, which means it loves to absorb moisture from the air; as water boils at 100°C, the more of it is in your brake fluid, the more spongy the brakes will feel, and ultimately the more likely they are to fade when used hard. As this absorption happens over time, it’s important to change the fluid at the specified times.
Most bikes use a DOT 4 fluid – a standard set by the Department of Transportation for minimum specifications. There are two boiling points; dry and wet. Dry is the boiling point of the fluid when it’s brand new; wet is the boiling point after it’s been in the system for a while, and has absorbed 3.7% of its volume in water.
DOT 5.1 is a glycol-based fluid that is compatible with DOT 4 fluid, and simply boils at a higher temperature. Don’t confuse it with DOT 5, which has the same higher boiling point, but is silicone-based, and must NOT be mixed with glycol-based fluids.
Brake fluid can typically be changed on a new bike equipped with ABS in just the same way as an older machine, but it’s very important that air is not allowed to enter the system during the process – if it does, you’ll definitely need to bleed the system carefully.
Bike Treads recommend Motul fluids, they are an industry leader and trusted by many professional garages and race teams. We use only Motul fluids in our workshop.
The general rule on most motorcycles is to have front and rear brake fluid changed every two years. The hydraulic clutch on many bikes use similar brake fluids or mineral oil, which should also be replaced every two years.
Should you service motorcycle suspension?
Degradation of your suspension is a very gradual thing. Many OE shock absorbers are deemed a sealed unit, but the oil in your forks can usually be changed by any garage. It’ll be a long time before it needs doing, but the problem is that, being such a gradual thing, you’ll probably not realize the handling has gone off.
Most manufacturers don't give a specific recommendation regarding changing the fork oil as it should be assessed as part of a bigger inspection of the front suspension, and carried out according to use. A racer would change the oil regularly as it’s put under a lot of stress and can have a real impact on lap times, but for a street rider there’s far less need, so it’s really down to owner discretion.
Our Advise: “Suspension is similar to an engine in that it’s a moving component that uses oil to create forces, to lubricate and goes through heat cycles (although not at such high temperatures).
“Keeping this in mind it’s always good practice to service forks and shocks on a regular basis, though obviously this differs from road to off-road and racing use due to the temperatures reached in operation. For road bikes I would say the norm would be around every 10,000 miles, while a competition shock might be around 20 hours.
“A front fork service would consist of stripping the units to the bare number of parts and cleaning everything, including the shims. A fork service would typically cost £120 to £150 in labour and parts such as oil seals and fork oil.
When to change motorcycle engine coolant?
The coolant in your bike – assuming it’s not got an air or oil-cooled motor – doesn’t just stop the engine getting too hot; it also prevents corrosion in the narrow pathways inside the engine, and lowers the freezing point. If you just put water in there, not only would there be a build-up of rust and limescale, the liquid could freeze, at which point it expands and can crack the engine (it’s why you might find expansion plugs built into some motors, just in case this happens). Over time, the protective qualities of the fluid degrade, so it needs to be replaced.
If you have to top up your cooling system between services, first question where the liquid has gone. If there are oil deposits in the fluid, it could be a sign of a damaged head gasket. Another indicator of this is a mayonnaise-like substance in the engine oil, though this can often be seen in small quantities due to condensation, especially if the engine is started but not allowed to get up to temperature. If all is well, you should only use de-ionised water, not plain or boiled water. However, as coolants are now available ready-mixed, and are far more compatible with each other than they used to be, you can top up very easily.
If you have an older bike with an unknown coolant in, it should be thoroughly flushed before replacing.
Most manufacturers recommend that coolant should be replaced every four years.
When to change motorcycle spark plugs?
Getting to the spark plugs on a bike can be a time-consuming job. With modern machines having overhead cams, the plugs tend to be buried down inside the cylinder heads, so it’s often necessary to remove the fuel tank and airbox.
Some corrosion might be visible on the outside of the plug, where water has got in (usually due to over-aggressive washing), but some bikes – like some KTM's and BMW's – have drain holes to allow the majority of the water to flow away. While plugs only generally need changing after a certain mileage – rather than time – if your bike isn’t getting used a lot, it’s worth keeping an eye on them for more severe corrosion.
Valve clearance checks and spark plug replacement will likely fall on the same service, as getting to this area is so labour-intensive.
Spark plug inspection and replacement is often different between manufacturers and the frequency is detailed in your model maintenance schedule.
When to change your motorcycle’s air filter?
A clogged air filter will cause your engine to run poorly, and in extreme cases, dust and grit could find its way into the motor with potentially devastating consequences.
For the average road-rider, sticking to the recommended service intervals will be fine. However, those riding in extreme locations – for instance across deserts – will need to change the filter more regularly. The tank will most likely need to be removed, but then accessing the filter is usually a simple job.
A clean air filter is necessary for the safe breathing of your engine, there are multiple aftermarket suppliers who offer lifetime air filter units but please be aware these still need regular checking, cleaning and oiling.
Servicing and motorcycle diagnostics / fault codes?
Modern bikes have a lot of electronic systems fitted, and European regulations now state that the fueling data must be accessible for checking. Like cars though, each manufacturer has specific technology, and will have its own computer systems to check and edit.
At Bike Treads we use a market leading TEXA diagnostic unit and a hybrid tablet/laptop that plugs into the bike and allows the adjustment of various parameters, and the resetting of fault codes.
There will usually be some faults stored that wouldn’t have affected the rider – sometimes simply turning the bike on and off too quickly can generate one, or running it on a paddock stand or dyno as the ABS gets confused by the mismatched wheel speeds. Wheelies can cause the same code to flag up.
While dealer-specific tools can restrict the abilities of independent workshops, they can be used to more quickly identify faults.
A specific tool used by main dealers can also identify breaks in the wiring loom – very useful on the complex CANbus systems of modern motorcycles, especially if the owner has fitted their own after-market electrical accessories. Our in-house TEXA diagnostic software is only limited by the release of new motorcycles and the frequency of data released for updates onto the plug-in tool. We regularly check and download new information to stay up-to-date.
Additional service items and checks for motorcycles?
Every bike might have specific parts that also require checking or replacing, A service will include an inspection of the bike – this will cover maintenance items like brake pads and chains and sprockets, which could need replacing, but also checking for worn fork seals, the state of the tyres, that all the fasteners are tight, and even for structural damage to the chassis. A skilled mechanic will understand what kind of life a bike has been having, and what areas could have been damaged, maybe by being dropped off-road.
Besides the service items listed above, here are the checks required during a generic FULL service:
Read fault codes using diagnostic tool
Check fuel system and lines
Check electrical equipment (eg lights etc)
Check brake discs and pads
Check tyre condition and pressures
Check brake fluid
Check brake lines
Check suspension for leaks and damage. Also clean fork dust boots.
Check chain and sprockets for wear and tension
Check coolant level
Check radiator function
Check cables for damage, and for routing with no sharp bends
Check steering head bearings for play
Check headlight position
Check clutch adjustment and pivot arm lubrication
Check swingarm bearings
Check wheel bearings
Grease all moving parts
Check all hoses for cracking, leaks and incorrect routing
Check the antifreeze
Check clutch fluid
Check all screws and nuts for tightness
Check for roadworthiness
Check battery health, charging system and charge rate.
Reset service interval display
At the end of the service, the technician will take your bike for a test ride to check that everything’s working correctly and that it’s safe to give back to you, unless you specifically ask for something like worn brakes to be left, in which case they may deem it unsuitable for them to carry out a road test.
A well-maintained bike will last longer, perform better and ultimately be a safer machine.