Mechanical Tips

Mechanical Tips
Submitted by diricia on Saturday, October 14, 2006 - 10:16

 

eng

 

Many people who take tours do an admirable job of preparing for every imaginable holiday eventuality - breakdowns excepted! I've included some practical advice from my own experience below - following it will substantially decrease the chance of a breakdown ruining your tour.

If you are not confident regarding mechanical matters, or you'd like an objective opinion regarding any problems, I'd be happy to examine your motorcycle for you or refer you to an authorized repair facility at least fifteen working days prior to your tour. Please note: I can only offer this service to those starting their tours in Gauteng - it's impossible for me to travel around the country tinkering with other people's bikes!

 

Preparation:

As with accomplishment of any successful task, preparation is nine-tenths of the job. Read up on your bikes' spec; get hold of all vital service info and manuals you need; buy the consumables. Make sure you have all the tools you need; DO NOT try to improvise or force something. Follow repair and maintenance instructions TO THE LETTER. If unsure of anything, ask a franchised service centre; chances are they know your bike far better than you do. If you want to perform maintenance yourself, become an expert on how your bike works.

Oh, and buy the Clymer or Haynes manual for your bike. It will pay for itself many times over in prevention of simple mistakes alone.

The vast majority of motorcycles produced within the last fifteen years, especially the German and Japanese marques, are tough and reliable. However, all need regular and sometimes quite involved - though straightforward - maintenance. The rapid advances in technology seen within the last two decades (stemming from the engineering one-upmanship that makes bikes lighter, faster, more reliable as well as more cost-effective to produce) have not made things any easier for the bike owner who'd rather do it himself - under-bucket valve shimming, electronic fuel injection, onboard diagnostics, components that cannot be dismantled except destructively, and equipment that cannot be serviced without special tools, have all conspired to make many tasks the province of franchised dealerships only.

Still, with a little perseverance, patience and the right information, there is little to stop you performing basic maintenance tasks on most machines yourself.

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Lubricants:

Being a mechanic by trade, I'm often asked the secret of long engine life. Nothing could be simpler: Use the best quality brand-name engine oil you can afford, and change it a lot. No matter what franchised service centres say, there is no such thing as changing the oil too often, and engine running-in is critical. Pay attention to the recommended viscosity grades for your particular engine (these can usually be found in your owner's manual. If not, ask your franchised workshop.) They are particularly important, especially if your engine is air- or air/oil-cooled. Always change the oil filter at the same time.

If you want to give a brand-new or freshly-rebuilt four-stroke engine the very best protection you can, use a dedicated running-in oil from brand-new and give the engine it's first oil and filter change at 1 000 Km (using no more than about 50% throttle and no more than 70% of the total rev range until then.) Use premium-quality mineral oil from 1 000 to 5 000 Km (using no more than about 70% throttle and no more than 80% of the total rev range until then), then drain the oil and change the filter again. From this point onward, feel free to use synthetic engine oil, but DON'T use it before this point: it will slow down the running-in process and may lead to consequential engine damage later.

For two-stroke bikes, the same rule applies: use high-octane fuel and use the best brand-name synthetic two-stroke oil you can find. Pay attention to whether the oil injection system on your bike is in top condition. If it isn't, chances are you can still ride the bike by pre-mixing your two-stroke oil and fuel. This must be done in the right ratio: too much oil will rapidly foul the spark plugs; too little will kill the cylinder bores. Be careful where you store two-stroke oil: unlike four-stroke engine oil, it burns readily.

If, like 95% of modern four-stroke bikes, your bikes' engine and gearbox share a common oil supply, do not use semi-synthetic or fully-synthetic oils designed for cars. They contain friction-modifying polymers that will degrade the friction properties of your clutch, causing it to slip. There are part- and full-synthetic oils designed for bikes; use them.

DO NOT use oil additives of any kind. The infomercials you see at three A.M. are masterful exercises in marketing, but the products themselves won't do your engine any favours. Most of them use liquid teflon or colloidal graphite - both substances were tried and abandoned for use in engine oil by mainstream petroleum manufacturers a long time ago. Teflon in particular breaks down rapidly under engine temperatures to form sludge, which clogs oil passages and ends up starving the engine of oil.

If your gearbox and engine are separate, pay grave attention to the recommended viscosity grade and API rating of your gearbox oil. If your gearbox requires, say, GL5 oil, use GL5 oil and nothing else. Beware of 'helpful' spares shop salespeople who would rather sell you the wrong oil than nothing at all. Soon after I bought my R1100S, I walked into three different automotive spares shops, looking for 80W-90 GL5 oil for the gearbox and rear drive unit. One tried to sell me SAE 85W-140 GL5 (way too thick), one, SAE 80 GL3 (a less protective oil designed for manual synchromesh transmissions), and one tried to sell me transformer oil (no API rating, and viscosity unknown, but somewhere in the region of tap water!)

All swore blind that those strange things I was so insistent on - viscosity and API rating - made no difference at all and that no harm would come of using these strange alternatives. If I'd used either of the last two I would've had to re-finance the bike to pay the transmission repair bill...

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Catalytic Converter:

If your bike is equipped with a catalytic converter and/or platinum or iridium-tipped spark plugs and/or exhaust oxygen-content sensors, do not use leaded fuel (this includes leaded racing fuel and AvGas): the lead content will react chemically with the rare earth metals used in these components and cause them to malfunction, leading to anything from misfires to loss of power to engine damage.

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Tyres:

Having lots in common with pure racing machinery has it's perks! Most motorcycle tyre manufacturers offer their wares in four grades of compound: Pure race (with three sub-categories: dry slick, semi-slick and wet treads), road-legal track compound, supersports and all-round (touring and commuting.) To give a discourse on the merits of one brand versus another would require a fully equipped lab and a Masters' degree in structural engineering, but I can give some useful tips:

Wherever possible, have your tyres inflated with nitrogen instead of air; there is less pressure variation with heat (this means more consistent handling, no matter if you're taking it easy or going nuts) and your tyres are likely to last longer without the rubber cracking or degrading, as nitrogen is inert.

For commuting and touring, go for the harder-compound all-round tyres. They offer better wear rates and your rear tyre won't square-off as soon. This means that your steering should stay sharper, and straight-line stability should stay intact (especially over uneven surfaces and white lines) for longer. The only time I recommend this rule be broken is on any bike with more than about 135 BHP - if you use full power with any sort of regularity there is less chance of the rear suddenly breaking loose and wheelspinning - especially in corners - if you use a supersports-compound tyre.

If you want to do track days (or don't care about wear rates), use supersports tyres. They have more grip than all-round tyres, and some of the newer makes - surprisingly - aren't so much of a compromise when it comes to wear. Road-legal track compound tyres are only ever useful for track days - they offer amazing grip when hot, but feel nervous and unstable on the road (you're never using them to their full potential, so they don't get a chance to heat up properly) and they wear terrifyingly fast.

Keep an eye on the rear tyre. Once the centre section starts to visibly square-off, it has little life left in it, and your handling and stability are already compromised. When this happens, replace the rear ASAP. As a rule of thumb, most road bikes consume one front tyre for every three rears.

Check your tyre pressures at least every couple of days; quite aside from preserving your handling, it may give you advance warning of slow leaks. Follow the bike manufacturer's specs, but if your tyres are slightly worn, increase the pressures front and rear by no more than 15 kPa. This helps offset the effects of the rear squaring-off - slightly.

Read, understand and follow the tyre specs supplied by the bikes' manufacturer. The current fashion trend among riders is to go one or two sizes larger on the rear tyre when the original wears out. Why? Because it looks cool. The trouble is that the wider you go on the rear, the more reluctant your bike will be to turn.

Each size of modern tyre is designed for a rim of specific width, and the tyre manufacturer specifies a tolerance of no more than half an inch either way. If it's recommended that your bike uses, say, a 170/60 on the rear and you ditch it for a 180/55 or a 190/50, you'll wonder why you're suddenly at the helm of what feels like a supertanker.

Puncture repair: due to the high expense of fitting new tyres, this is a controversial issue among riders!

Most tyre manufacturers recommend no more than two tubeless repairs (a special plug coated in rubber cement) per tyre, and recommend that you replace the affected tyre as soon as possible.

The wheel should always be dynamically balanced after any such repair.

I don't recommend Tyre Weld or similar aerosol repairs - carry a tubeless repair kit with carbon dioxide cylinders instead. They are cheap, and give a far more reliable (and therefore safer) repair. Plus, whoever does a permanent repair on the tyre won't have to scrape out any gunk before he does so.

If a puncture has been repaired by any means, I don't recommend sustained running above 200 Km/h, or exceeding 250 Km/h. (Hint: If you can't figure out how a blowout at that speed will end, look on the internet for the post-surgery X-rays of Barry Sheene's hips.)

If you want an easier life with regard to tyre choice, don't buy any bike that uses, say, 18-inch rear tyres or 16-inch fronts. Such tyres are difficult and expensive to obtain. The universal standard rim diameter these days is 17-inch and it's where all bike-tyre manufacturers concentrate 95% of their effort.

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Suspension adjustment:

If you carry a pillion and/or luggage on the bike, suspension adjustment becomes fairly critical, especially for high-speed running.

Under these circumstances, the adjustment that will make the most difference to the bike's handling is rear spring preload. As a rule, the heavier the load the bike carries, the higher the preload should be - although it is nearly always higher on the rear than the front.

As a rule of thumb, the amount of rebound damping is about four times the compression damping. Compression and rebound damping should be adjusted upward (i.e. more damping) the smoother the surface, and vice versa. However, these are the most handling-sensitive adjustments and I strongly suggest you get a suspension expert to adjust them for you. As a rule, too little damping will cause the bike (especially the rear) to wallow in turns and/or weave at high speed. Too much damping will cause the front end not to feel ''planted''; the bike will dart about and feel nervous, unpredictable and uncomfortable.

Riders who ride more aggressively can speed up their steering (depending on front suspension design) by dropping the steering yokes a few millimetres down the fork legs, and increasing the rear spring preload. The cumulative effect of these two modifications is to decrease the steering rake. Another means of achieving this is to use a lower-profile front tyre eg if you normally use a 120/70, use a 120/65 or 120/60 instead. This has the added effect of shortening the wheelbase slightly. CAUTION: The mods above are performed at your own risk! If you do lower the front end, be aware that different parts of your bike may now touch down during cornering. You may also make the bike more susceptible to tank-slapping over bumpy roads or during sudden manoeuvres.

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Steering damper:

If your bike has an adjustable steering damper, use it on the lightest possible setting that will suppress any tendency to tank-slap over bumps. High settings mean that steering becomes hard work.

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Brakes and brake pads:

Depending on your make and model of bike, different grades of brake pad compound may be available. Organic-content pads are rare, mostly used on the rear, and their performance is very average. However, they are kind to brake discs and their dust is easier to clean off. Sintered-metal content pads are the current state-of-the-art. They have a high metal content to transfer heat rapidly away from discs and improve their friction coefficient. If using race-compound pads on a road bike, I strongly recommend you use them only on the front (there is every chance they may lock up the rear wheel too easily), and set aside some practice time to accustom yourself to what your brakes are now capable of - they may be VERY fierce.

Always bed the pads in according to the pad manufacturer's recommendations.

When changing your brake and clutch fluid, replace it with DOT4 fluid only. Shop around for fluid with the highest boiling point you can find. If you want to use DOT5 fluid, first check whether it is compatible with your brake system, as it is silicone-, not glycol-based. Silicone-free DOT 5.1 fluids are also available.

If your brakes lack power and/or feel wooden, stainless-steel-braided teflon brake hoses are a sensible modification. They greatly improve ease of modulation, and give a slight improvement in power.

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Regular service items:

Head bearings: Butt the bike front wheel-first against a wall and push it back and forth. If you feel a click or any play through the head bearings, they will need to be tightened. Get the front wheel off the ground and disconnect the steering damper if your bike has one. Move the steering from side to side. If it does not move smoothly and easily, the bearings will need to be loosened.

Battery:
Many modern bikes are fitted with sealed batteries which cannot be "maintained" in the true sense of the word. A sensible check to apply every so often is to determine whether the starter motor cranks the engine easily with the low-voltage side of the ignition coil disengaged, transmission in gear, the clutch disengaged and the headlights on high beam. If you have access to a voltmeter, check the battery voltage as the above test is performed. On a bike with a 12-volt electrical system, the battery voltage should not drop below 9.6V after 10 seconds of cranking.

Batteries should always be kept scrupulously clean, especially around their terminals.

If you use lots of accessories (headlights on all the time, heated grips, etc.) it's worthwhile considering a battery of a slightly higher Ah (Amp-hour) rating, as it will take the load a bit more easily.

If the battery is not sealed, check it's electrolyte level. If low, fill with nothing but distilled water (available at any pharmacy); tap water contains impurities that will damage it. Do not be tempted to overfill the battery - the excess electrolyte will bleed through the vent holes and seriously corrode everything it touches.

Brakes:
Check the thickness of all pads (remove the calipers if you have to.) If out of specification, replace them promptly. More aggressive riders should replace the pads some time before they reach their wear limit: worn pads don't dissipate heat as effectively. Disc thickness and wear should be checked at the same time. Make sure that pads are not binding (dragging) on discs, and that the discs themselves are not warped, both before and after any work. Brake and clutch fluids (three separate hydraulic circuits if your bike has a hydraulic clutch) should be changed at least every twelve months and few bike shops bother to do this. Check for leaks at all the brake unions, but don't habitually re-tighten at every check; you may strip the threads. If your brakes have overheated at any time, change the pads (they have now faded and can no longer give their best) and bleed the brakes. Don't be afraid to use the brakes fairly hard either; if you use them too gently all the time, you will glaze the pads, robbing them of power. Check to see if the front and rear brake light switches are correctly set.

If you do track days, I recommend you bleed the brakes after every track day.

Safety-critical fasteners: Check the torque values of the front and rear wheel spindle and their fastening bolts, head bearing securing nut, fork clamps, swingarm bearings and head bearings (if you know their correct torque values!) Also check the securing bolts for the side and centre stands.

Throttle and choke: Check the cable slack according to recommendations and adjust as necessary.

Lights:
Chances are you won't have a headlight aiming device in your trusty toolbox, so if in any doubt, take it to a dealer to have it checked (especially if you keep getting flashed at night with your lights on dipped beam.) Check regularly that your headlight(s), turn signal lights, taillight, licence plate light, instrument panel lights and horn are in good order. Bikes that have a lot of inherent vibration (especially big singles and twins) tend to blow bulbs more easily; this is normal, though irritating.

Coolant: If your bike is water-cooled, the coolant mixture usually has a replacement interval, and the coolant strength (specific gravity) should be checked at every service with an appropriate hydrometer. Have it checked, and look for leaks at the same time.

Air filter:
Cleaning air filters out with compressed air isn't a good idea, no matter what the manufacturer says: it's too easy to blow holes in the filter matrix. For dirty paper filters: replace with a new one. For foam (eg Pipercross) and cleanable cotton-gauze filters (eg K&N or BMC), soak them in an approved filter cleaner (NOT ordinary detergent) and leave to stand for a while. Flush them with tap water at low flow from the clean side to the dirty side until no more dirt is visible in the water. Then, air-dry the filter (do not leave in the sun or expose to excessive heat) and re-oil it using an approved filter oil - NOT engine oil.

Clutch: If the bike is equipped with a cable clutch, adjust the clutch play at the lever. Hydraulic clutches do not need adjustment.

Spark plugs: Check their air-gap against recommended specs. Clean and re-gap if permissible (Platinum and Iridium plugs cannot be re-gapped.) Replace if worn. Use the specified grade of plug; too hot and the engine will detonate (ping); too cold and the plugs will foul and result in hard starting and poor fuel economy.

Carburettors: If your bike has them and has more than one cylinder, they should be synchronised (balanced) using vacuum gauges at recommended intervals. If in doubt of your ability to do it (it is tricky), leave this to your dealer. If you want to do it yourself, get hold of the Haynes manual or workshop manual for your bike.

Engine: Valve clearances should be set at the recommended intervals, to within 0.10 millimetres of the manufacturer's spec. Most engines older than twenty years have their clearances adjusted by screw and locknut. Over-bucket shims need a special tool to depress the buckets and remove them. Underbucket shims require you to remove the camshafts and buckets to get at them. Nearly all Ducatis and a few Hondas have desmodromic valvegear (the valves are opened by cams, but closed by gears instead of springs.) Servicing of these engines is for skilled experts only.

I recommend that all bikes be equipped with good fuel filters, whether fuel-injected or not. Apropos of injected bikes: let all fuel drain from the removed filter until it's dry, then blow from the dirty side to the clean side. if you can't blow easily through the fuel filter, it's blocked and needs replacing. Never try to clean a fuel filter.

Chain and sprockets:
These are safety-critical items: if you don't know what happens when a drive chain snaps under high load, make friends with someone who races bikes and get him to tell you...!

Centre stands are a very good idea when touring, because they allow you to get the back wheel off the ground to clean and lube the chain. O-ring and X-ring chains are more expensive, but more reliable and longer-lasting. I recommend that you lube and adjust the chain at least every 1000 kilometres (620 miles) or if you see that the rollers are dry. Every so often, clean your chain and sprockets with fresh diesel fuel and flush with water. Dry the chain as quickly as possible, and re-lube using a quality name-brand anti-fling chain lubricant, like Castrol Chain Wax or PJ-1. Better yet, invest in a Scottoiler or an equivalent.

Make sure the chain free-play is within spec. Too tight and your gearbox bearings will take unnecessary strain, too loose and the chain could jump off the sprockets.

Your sprockets are no longer serviceable when the teeth are worn into a crescent- or shark-tooth shape and/or the portion of chain engaging with the rear sprocket can be lifted more than about 3 or 4 millimetres off the sprocket.

Be aware, too, that it is possible for a chain to wear out without stretching. Always change the drive chain and both sprockets together as a matched set: Used sprockets will destroy a new chain and vice versa.

For toothed rubber belt drives (Harley-Davidson, Buell, BMW F650CS and F800-series, and a few others), the belt has a very long lifespan and doesn't need regular servicing except for periodic tension checks and replacement. They don't need lubrication. Some are guaranteed for life. However, it's worthwhile checking for cracks or splits in the belt every so often. Do not let grease or oil come into contact with the belt. If the belt has been contaminated in this way, replace it at once.

Shaft drives are usually maintenance-free. However, I'd recommend draining and replacing the drive unit oil every 30 000 kilometres or so, if only for peace of mind. If the drive unit is making a loudish humming noise, get it checked professionally - it is probably badly worn.

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Other stuff:

Even if your bike wasn't originally equipped with one, it's an excellent idea to carry your own toolkit. This should include a tubeless puncture repair kit with carbon-dioxide cylinders, spare inner tube, tyre levers, fuses, insulation tape, chain lube (which doubles neatly as emergency all-purpose lubricant), a clean rag, a small flashlight and the main spanner/Allen wrench sizes for your bike. If you ride a two-stroke, include a couple of spare spark plugs and a spark plug wrench. Pack it all in a tough plastic bag or Ziploc bag for waterproofing. In most cases, it should all fit under the seat.

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Please note: this information is published in good faith. Atreus CrossTours will not accept liability for any mechanical failure, accident, injury or death which may come about by any means. In particular, no responsibility will be borne by Atreus CrossTours or it's agents, representatives or employees for any injury, death, damage or loss sustained as a result of following any advice in the article above. Atreus CrossTours strongly recommend that you follow your motorcycle manufacturer's recommendations and advice regarding maintenance and repair at all times, attend mechanical training courses, buy and use the right tools, and ride safely.

Safety first!


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