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Buying a Used Motorcycle
What to look for...and why
by Robert Scott-Buccleuch
edited by JP Honeywell
Every disclaimer you have ever heard or read about applies. Follow the links to find out more about each topic.
Purchasing a used motorcycle privately?
This is tricky at best and you must be sure to inspect the vehicle to make certain that there are no suprises later on when you are paying for the certification. I have a sheet that I use to go over the bike in an orderly fashion and that way I don't miss anything important. Prices of motorcycles have risen with demand and replacement parts are more expensive than ever before so be careful when adding up the parts you may need to purchase.
Tires
Tires are a rather important part of the motorcycle and should be inspected carefully. Wear, of course, is the most noticable and the tire will have a wear bar (slightly higher rib across the tire that the wear is measured from) Uneven wear and cupping of the tread will show whether the tire has been ridden on improper air pressures. Also check for cracks on the sidewall. These can be tricky to spot so have good lighting or a flashlight so you can inspect the side of the tire properly. If the tire is soft from sitting, you may not see the cracks until you get the correct air pressure in the tire
Wheels
Wheels are not tires...they are what the tire sits on. There are spoke wheels and cast (one piece or "mag" wheels) You want to spin the wheel to check several things. Must be straight, ie. no side to side runout. The up and down runout should not be noticable either. Don't mistake tire runout with wheel runout. Grab the wheel and try to move it side to side. No movement should be observed...if there is any, the wheel bearing may be worn. Also apply the brake and release it and make sure the wheel can spin as freely as before. If not then you may have a brake problem.
Front Fender
The front fender should be there. It has to be mounted securely and usually bolts to the lower fork slider. Check that the mounting bolts are there and tight. Aso check that the bolts haven't been broken off. A good shop will check this for a certification and getting those broken bolts out of the slider can be a real pain. Make sure there are no cracks in the fender. A lot of them are plastic. If you see a cracked fender or a bent fork brace then the fork tubes may well be bent, telling you that the bike has been down and not totally repaired. The bent fork brace or missing fork brace is a sure bet givaway that the forks are bent so keep an eye out for that.
Brakes...disc
You have to be careful when checking disc brakes. There is the brake fluid to inspect. Pad wear must be addressed. The condition of the rotor itself has to be looked at. These are very expensive to replace and they do wear. Feel the edge and if there is a ridge at the outer edge then they have worn. If the lever comes into the bar when the brakes are applied then it may be rotor time The only way to really tell is with the specs and a vernier. When looking at a potential purchase you probably won't be able to check and measure everything so see if the brake lever can be pulled into the handlebar. Check for brake fluid leakage from the area of the master cylinder.
The pads can be inspected by looking at the caliper from the front, looking up. A brake pad should be on either side of the brake rotor. Sometimes there is a red wear line you can see. Having a small flashlight will really help out here. There should, of course, be pad material on the pad. If it has worn to metal then the disc will have a rough finish and be burnt looking.
Brakes...Drum
You won't find many street bikes that have drum brakes on the front wheel, they are still to be found as the rear brake on some models. They are usually mechanically operated, activated by a foot lever located near the right side footrest. At the rear wheel there may be an indicator close to the actuator cam shaft, but that is a rough guide at best. To really inspect the remaining brake shoe life you must take the wheel off the bike.
Some off road or enduro style bikes may have cable activated front brakes and the thing to look for here is a siezed cable (it will cause the brakes to stay engaged...not good) also, there will be cable adjusters, that compensate for cable stretch, make sure that these are not all the way out, thus indicating that the cable is totaly stretched.
Brakes...master cylinder
The master cylinder is where the brake fluid is kept... usually attached to the handlebar for front brakes and tucked away, close to the rear brake pedal for the rear brake. The main problem that occurs with these is the brake fluid itself. There is a piston in the master that is activated by the lever that you pull. If this piston is leaking then the brakes can be mushy or there may be brake fuid leaking from the area around the master cylinder. There is a very small hole in the master that allows brake fluid to return back up to the master and if this is blocked due to corrosion then the href=#q>lever will be very hard but no or little braking action will be taking place. If you experience problems with a master cylinder then you may be better off paying someone to look at this for you.
Brake Calipers
In the caliper a piston is activated by you when you pull the front brake lever. It pushes against the actual brake pads to apply pressure on the disc. One or several (depending on make) "rubber" o-rings seal the fluid from escaping between the piston and wall of the caliper. These rings serve another function and that is to return the piston to its original position (brakes off) These rings are the only thing returning this piston and when there is corrosion, the piston can be forced on because the hydraulic pressure is great enough to do so, however there is no (hydraulic) help for the piston to return and thus causes the brakes to be applied even though we are not pulling the lever. The resulting application of the brakes causes a heat build up, brake fluid expands (due to heat) thus forcing the brakes on even more. This is not a good situation to be in as a motorcyclist.
I've seen bikes pull into the shop with the rear disc brake so hot that it is glowing cherry red with heat build up. The brake pads were totally worn away and the repair parts this bike would need include caliper assembly, disc brake rotor, wheel bearings and all dust seals. Expensive!!!
How If They Are Seized?
Elevate the wheel in question and spin it. Apply the brake to that wheel and release the brake. Does the wheel spin now? Is it a little harder to spin than it was before you applied the brake?
Previous experience plays a large part of what you do next because all disc brakes "drag" a little and that must not be mistaken for seized brakes. To tell whether the brakes are truly seized, hit the caliper with a "dead blow" hammer (soft mallet, so as not to mark the caliper) If the wheel spins with less drag than before, then the brakes are sticking on and must be repaired.
When you are riding the bike pull in the clutch and coast every once in awhile. Does the bike slow down too quickly? Does everything sound OK?
Catch it early and you will save yourself expensive repairs.
Brake Fluid
Master cylinders are where you will check the condition of the brake fluid. They will have a little window to look through or unscrew the top cover and have a look. It should be changed every year but few riders do this. If it black or even dark brown in colour then it has to be changed. It should be almost clear in colour. This includes the fluid in the lines and caliper. DOT 3 and 4 are the most widely used brake fluids. Dot 4 has a slightly higher boiling point than DOT 3. Please be aware than brake fluid eats paint and if you are working with it then cover any painted parts. Plastic will break into small pieces about a day after having brake fluid spilled on it. DOT 5, used in most Harley Davidson motorcycles now, is silicon based and has a slight purple haze to it. It does not corrode paint or plastic, does not go bad as quickly, has a higher boiling point...all very good reasons to switch to it. If you switch then the system must be flushed. It is not compatable with DOT 3&4 (it will turn everything to jello If you are not sure....then pay someone to do it for you.
Brake Lights
Brake lights have to work. Both common sense and the law dictate that you want these lights to work. They are operated by a switch which is activated by you pressing the pedal or pulling the lever. Usually it is not a big deal to make these work if out of adjustment, if broken, they are not too much money... just buy one and replace it. The bulb is usually the culprit or a misadjusted switch, sometimes even a loose wire... the point is, if they don't work it is not safe to operate the bike. The way the switch is located exposes it to the elements and they can get corroded easily. A little lube every now and again will keep them working longer.
Front Forks
The forks are a very important part of the bike as they provide the front suspension of the vehicle. Having oil as the damping agent means that there is an oil seal to keep it contained. One per fork and if these start to leak the oil will be all over your brakes and pants and not in the fork to help dampen the load. This can cause handling problems as well as ruin a set or two of brake pads. There is a tell tail ring of oil around the fork tube so rock the (parked) bike a few times, with the front brake on and then inspect the fork tube...any oil???
The forks can also be bent and a slight bend is hard to spot. Look at the forks from the side, line up both forks visually...are they in line with one another? If not, they are bent or twisted in the crowns meaning the front end has impacted with something.
Also the forks may be damaged by pitting or rust and the chrome coating may have started to lift meaning that the rubber fork seal will get ripped every time that it passes the damaged area. These can be expensive to purchase.
Steering Head
The steering head is what the whole front end assembly swivels on. There are bearings hidden away in there that sometimes need adjustment or replacement. You can tell if this is the case by grabbing a handful of front brake and rocking the bike forward and backward. If you can hear or feel any play then adjustment or replacement is required. Also, elevate the front end and turn the front end from full left lock to full right lock. Is there any notching or grabbing in the movement? If so...then it is time for new bearings and races.
Steering Stops
Steering stops are an important feature of motorcycles that prevent the front forks from hitting the fuel tank at full lock. When a motorcycle falls, the forks tend to jam up against the stop and bend or break it off. If the handlebars come really close to the tank or hit it then the steering stop has to be rewelded or repaired to make it safe to operate. Because of the different designs of steering stops there is no fixed price for repair and varies depending who is doing the work. If the repair is made by arc welding, the steering head bearings must be regreased as the heat from welding will have melted away any grease.
Handlebars
Older bikes have one piece handlebars, newer styles have two, each one is slipped over the fork tube. The difference is style and price. The older style bar is by far a lot cheaper to replace than the newer style. They should not be bent. If they are, then it tells you the bike has fallen. The throttle side is the more important of the two because if it bends then the bend can sieze the throttle tube which spins on top of the bar.
You should not bend them back to shape...here's why. On the first bend the outside of the actual bend (of the bar) is stretched and weakened. Not good... but possibly still drivable. If you bend it back then you now stretch the opposite side (of the bend) and weaken it even more...possibly to the point it may break while driving.
Throttle Grip
This is the twist grip that pulls the cable that increases the fuel to the motor that makes the bike go faster. The main thing to check here is that the throttle closes by itself. It should snap shut. If it is hanging up then the problem must be addressed to make the bike safe... and pass a certification. Usually the cable needs a little lube or is href=#cr>routed incorrectly. Lite grease on the bar and inside of throttle tube will help as well. If you purchase a set of grips, you will notice that the inside holes are differant sizes and this is because the throttle tube is only on the right side of the bars... one grip of the two is larger than the other and the larger of the two goes on the right side (sitting on the bike).
Kill Switch
The "kill switch" or engine shut-off switch, as some people prefer to call it, is an added safety feature that enables you to shut off the motor without removing your hand from the handlebars. It should move to it's off or on position with a bit of a "click" If it feels mushy or loose then it may well be on it's way out. If it breaks inside, then the motor will stop working and it can be hard to track down the problem. Remember... look first for the items that get used the most... they will break first.
Handlebar Controls
No one pays much attention to these componants and hey... what to keep adjusted...nothing. Just make sure they function and are not ready to fall off. If one of those itty bitty levers for the signals or high beam, for example, falls off ...you have to buy the whole assembly to the tune of nearly $100.00 each side if you live in Canada (some models are more). If the bike you are looking at is missing those, don't get sucked in by the old "...oh, how much could that little thing cost"
Levers
Levers pull the cables that operate various systems of the motorcycle. If the ends are scuffed then you know that it has impacted something, probably lightly as they are the first to go in any fall. Good idea to have some spares on any long tour you may make. They should have some freeplay and not be bent. They usually snap if you try to straighten them.
Cables
When you pull the lever the cable should have a smooth action and return to its original position sharply. There should be freeplay at the control end of the cable. You shouldn't be able to see any broken strands of wire. You should see some sign that the owner has lubed it.
Cable Routing
The perfect routing for a cable would be a straight line. That is not possible on a motorcycle so as straight as you are able to make them is the rule. When inspecting the bike, turn the bars from side to side and make sure that the cables don't get pinched by the forks or pulled too tight at full lock. If a thottle cable gets pulled on when the bars are turned a certain way then you are an accident waiting to happen. Factory service manuals usually have several pages devoted to cable routing. Certain models of bikes may have different needs in terms of where the cable has to go to function correctly.
Sprockets
Sprockets are what the chain rides on to transfer the horsepower from the motor to the rear wheel. They have a given number of teeth which the chain engages with. You must look sideways at the sprocket and see if the teeth are hooked at all. They should be flat at the end...if they are sharp, then the sprocket is worn. The higher the horsepower of the bike then the faster the sprockets wear. If the sprocket is replaced then the chain should be replaced as well. Spinning the rear wheel backwards (elevated and by hand) you will hear the chain grabbing if there is any hooking.
Chain
When you inspect that potential purchase for chain wear you can look to see how far back the wheel has been adjusted to. If the adjusters are screwed in all the way, then it's a sure sign that the chain is totally worn. If the chain pulls back from the back of the rear sprocket then it worn.
Shaft Systems
The shaft drive system is almost maintenance free. At the rear axle you will see that oil goes in the rear housing. There is a large bolt in the top which, when removed, is where you pour in the oil. A smaller bolt on the side about half way up the housing is the level check. If you remove it then the oil should be at that level. There is another bolt at the bottom and that is the drain bolt. The oil used is a mineral based oil, Hypoid, and it has a unique odour to it. Don't use ordinary oil. You shouldn't have to worry about anything in this setup because it is rather bulletproof.
Shocks
The front suspension we have covered and the same theory applies to the rear suspension. There are two types... Dual shocks and Monoshock...
Monoshocks are not as easy to spot because they are tucked away in the guts of the bike. Look in front of the rear wheel and there should be a tube like cylinder running up to just under the front of the seat. It may be shrouded and all you can do would be to look for oil leakage in the area. The best test is to bounce the suspension and see how it reacts.
Dual shock types of suspension are totally visable and there will be one on each side of the bike, attaching the rear of the swingarm to the rear area of the frame, usually near the back of the seat. They should be straight, no oil leakage is supposted to be there. Once again the best test is to bounce the suspension and see how it reacts. (I will add to this in the near future
Swingarm
The swingarm holds the rear wheel and pivots up and down to allow for suspension travel. There is not much to go wrong with a swingarm except the side to side play it may develop. With the bike on the centerstand (or elevated) grab the swingarm and apply side to side force. If side to side play is found then you would have to tighten the swingarm nut. If it is already at the required torque then the swingarm bearing or bushings need to be replaced. This kind of job you may wish to pay a service shop to do for you.
More....
This is a very basic guide for those of you who don't know too much about bikes and I hope it has been of some use to you.
Copyright 1996, Robert Scott-Buccleuch
What to look for...and why
by Robert Scott-Buccleuch
edited by JP Honeywell
Every disclaimer you have ever heard or read about applies. Follow the links to find out more about each topic.
Purchasing a used motorcycle privately?
This is tricky at best and you must be sure to inspect the vehicle to make certain that there are no suprises later on when you are paying for the certification. I have a sheet that I use to go over the bike in an orderly fashion and that way I don't miss anything important. Prices of motorcycles have risen with demand and replacement parts are more expensive than ever before so be careful when adding up the parts you may need to purchase.
Tires
Tires are a rather important part of the motorcycle and should be inspected carefully. Wear, of course, is the most noticable and the tire will have a wear bar (slightly higher rib across the tire that the wear is measured from) Uneven wear and cupping of the tread will show whether the tire has been ridden on improper air pressures. Also check for cracks on the sidewall. These can be tricky to spot so have good lighting or a flashlight so you can inspect the side of the tire properly. If the tire is soft from sitting, you may not see the cracks until you get the correct air pressure in the tire
Wheels
Wheels are not tires...they are what the tire sits on. There are spoke wheels and cast (one piece or "mag" wheels) You want to spin the wheel to check several things. Must be straight, ie. no side to side runout. The up and down runout should not be noticable either. Don't mistake tire runout with wheel runout. Grab the wheel and try to move it side to side. No movement should be observed...if there is any, the wheel bearing may be worn. Also apply the brake and release it and make sure the wheel can spin as freely as before. If not then you may have a brake problem.
Front Fender
The front fender should be there. It has to be mounted securely and usually bolts to the lower fork slider. Check that the mounting bolts are there and tight. Aso check that the bolts haven't been broken off. A good shop will check this for a certification and getting those broken bolts out of the slider can be a real pain. Make sure there are no cracks in the fender. A lot of them are plastic. If you see a cracked fender or a bent fork brace then the fork tubes may well be bent, telling you that the bike has been down and not totally repaired. The bent fork brace or missing fork brace is a sure bet givaway that the forks are bent so keep an eye out for that.
Brakes...disc
You have to be careful when checking disc brakes. There is the brake fluid to inspect. Pad wear must be addressed. The condition of the rotor itself has to be looked at. These are very expensive to replace and they do wear. Feel the edge and if there is a ridge at the outer edge then they have worn. If the lever comes into the bar when the brakes are applied then it may be rotor time
The only way to really tell is with the specs and a vernier. When looking at a potential purchase you probably won't be able to check and measure everything so see if the brake lever can be pulled into the handlebar. Check for brake fluid leakage from the area of the master cylinder.The pads can be inspected by looking at the caliper from the front, looking up. A brake pad should be on either side of the brake rotor. Sometimes there is a red wear line you can see. Having a small flashlight will really help out here. There should, of course, be pad material on the pad. If it has worn to metal then the disc will have a rough finish and be burnt looking.
Brakes...Drum
You won't find many street bikes that have drum brakes on the front wheel, they are still to be found as the rear brake on some models. They are usually mechanically operated, activated by a foot lever located near the right side footrest. At the rear wheel there may be an indicator close to the actuator cam shaft, but that is a rough guide at best. To really inspect the remaining brake shoe life you must take the wheel off the bike.
Some off road or enduro style bikes may have cable activated front brakes and the thing to look for here is a siezed cable (it will cause the brakes to stay engaged...not good) also, there will be cable adjusters, that compensate for cable stretch, make sure that these are not all the way out, thus indicating that the cable is totaly stretched.
Brakes...master cylinder
The master cylinder is where the brake fluid is kept... usually attached to the handlebar for front brakes and tucked away, close to the rear brake pedal for the rear brake. The main problem that occurs with these is the brake fluid itself. There is a piston in the master that is activated by the lever that you pull. If this piston is leaking then the brakes can be mushy or there may be brake fuid leaking from the area around the master cylinder. There is a very small hole in the master that allows brake fluid to return back up to the master and if this is blocked due to corrosion then the href=#q>lever will be very hard but no or little braking action will be taking place. If you experience problems with a master cylinder then you may be better off paying someone to look at this for you.
Brake Calipers
In the caliper a piston is activated by you when you pull the front brake lever. It pushes against the actual brake pads to apply pressure on the disc. One or several (depending on make) "rubber" o-rings seal the fluid from escaping between the piston and wall of the caliper. These rings serve another function and that is to return the piston to its original position (brakes off) These rings are the only thing returning this piston and when there is corrosion, the piston can be forced on because the hydraulic pressure is great enough to do so, however there is no (hydraulic) help for the piston to return and thus causes the brakes to be applied even though we are not pulling the lever. The resulting application of the brakes causes a heat build up, brake fluid expands (due to heat) thus forcing the brakes on even more. This is not a good situation to be in as a motorcyclist.
I've seen bikes pull into the shop with the rear disc brake so hot that it is glowing cherry red with heat build up. The brake pads were totally worn away and the repair parts this bike would need include caliper assembly, disc brake rotor, wheel bearings and all dust seals. Expensive!!!
How If They Are Seized?
Elevate the wheel in question and spin it. Apply the brake to that wheel and release the brake. Does the wheel spin now? Is it a little harder to spin than it was before you applied the brake?
Previous experience plays a large part of what you do next because all disc brakes "drag" a little and that must not be mistaken for seized brakes. To tell whether the brakes are truly seized, hit the caliper with a "dead blow" hammer (soft mallet, so as not to mark the caliper) If the wheel spins with less drag than before, then the brakes are sticking on and must be repaired.
When you are riding the bike pull in the clutch and coast every once in awhile. Does the bike slow down too quickly? Does everything sound OK?
Catch it early and you will save yourself expensive repairs.
Brake Fluid
Master cylinders are where you will check the condition of the brake fluid. They will have a little window to look through or unscrew the top cover and have a look. It should be changed every year but few riders do this. If it black or even dark brown in colour then it has to be changed. It should be almost clear in colour. This includes the fluid in the lines and caliper. DOT 3 and 4 are the most widely used brake fluids. Dot 4 has a slightly higher boiling point than DOT 3. Please be aware than brake fluid eats paint and if you are working with it then cover any painted parts. Plastic will break into small pieces about a day after having brake fluid spilled on it. DOT 5, used in most Harley Davidson motorcycles now, is silicon based and has a slight purple haze to it. It does not corrode paint or plastic, does not go bad as quickly, has a higher boiling point...all very good reasons to switch to it. If you switch then the system must be flushed. It is not compatable with DOT 3&4 (it will turn everything to jello
If you are not sure....then pay someone to do it for you.Brake Lights
Brake lights have to work. Both common sense and the law dictate that you want these lights to work. They are operated by a switch which is activated by you pressing the pedal or pulling the lever. Usually it is not a big deal to make these work if out of adjustment, if broken, they are not too much money... just buy one and replace it. The bulb is usually the culprit or a misadjusted switch, sometimes even a loose wire... the point is, if they don't work it is not safe to operate the bike. The way the switch is located exposes it to the elements and they can get corroded easily. A little lube every now and again will keep them working longer.
Front Forks
The forks are a very important part of the bike as they provide the front suspension of the vehicle. Having oil as the damping agent means that there is an oil seal to keep it contained. One per fork and if these start to leak the oil will be all over your brakes and pants and not in the fork to help dampen the load. This can cause handling problems as well as ruin a set or two of brake pads. There is a tell tail ring of oil around the fork tube so rock the (parked) bike a few times, with the front brake on and then inspect the fork tube...any oil???
The forks can also be bent and a slight bend is hard to spot. Look at the forks from the side, line up both forks visually...are they in line with one another? If not, they are bent or twisted in the crowns meaning the front end has impacted with something.
Also the forks may be damaged by pitting or rust and the chrome coating may have started to lift meaning that the rubber fork seal will get ripped every time that it passes the damaged area. These can be expensive to purchase.
Steering Head
The steering head is what the whole front end assembly swivels on. There are bearings hidden away in there that sometimes need adjustment or replacement. You can tell if this is the case by grabbing a handful of front brake and rocking the bike forward and backward. If you can hear or feel any play then adjustment or replacement is required. Also, elevate the front end and turn the front end from full left lock to full right lock. Is there any notching or grabbing in the movement? If so...then it is time for new bearings and races.
Steering Stops
Steering stops are an important feature of motorcycles that prevent the front forks from hitting the fuel tank at full lock. When a motorcycle falls, the forks tend to jam up against the stop and bend or break it off. If the handlebars come really close to the tank or hit it then the steering stop has to be rewelded or repaired to make it safe to operate. Because of the different designs of steering stops there is no fixed price for repair and varies depending who is doing the work. If the repair is made by arc welding, the steering head bearings must be regreased as the heat from welding will have melted away any grease.
Handlebars
Older bikes have one piece handlebars, newer styles have two, each one is slipped over the fork tube. The difference is style and price. The older style bar is by far a lot cheaper to replace than the newer style. They should not be bent. If they are, then it tells you the bike has fallen. The throttle side is the more important of the two because if it bends then the bend can sieze the throttle tube which spins on top of the bar.
You should not bend them back to shape...here's why. On the first bend the outside of the actual bend (of the bar) is stretched and weakened. Not good... but possibly still drivable. If you bend it back then you now stretch the opposite side (of the bend) and weaken it even more...possibly to the point it may break while driving.
Throttle Grip
This is the twist grip that pulls the cable that increases the fuel to the motor that makes the bike go faster. The main thing to check here is that the throttle closes by itself. It should snap shut. If it is hanging up then the problem must be addressed to make the bike safe... and pass a certification. Usually the cable needs a little lube or is href=#cr>routed incorrectly. Lite grease on the bar and inside of throttle tube will help as well. If you purchase a set of grips, you will notice that the inside holes are differant sizes and this is because the throttle tube is only on the right side of the bars... one grip of the two is larger than the other and the larger of the two goes on the right side (sitting on the bike).
Kill Switch
The "kill switch" or engine shut-off switch, as some people prefer to call it, is an added safety feature that enables you to shut off the motor without removing your hand from the handlebars. It should move to it's off or on position with a bit of a "click" If it feels mushy or loose then it may well be on it's way out. If it breaks inside, then the motor will stop working and it can be hard to track down the problem. Remember... look first for the items that get used the most... they will break first.
Handlebar Controls
No one pays much attention to these componants and hey... what to keep adjusted...nothing. Just make sure they function and are not ready to fall off. If one of those itty bitty levers for the signals or high beam, for example, falls off ...you have to buy the whole assembly to the tune of nearly $100.00 each side if you live in Canada (some models are more). If the bike you are looking at is missing those, don't get sucked in by the old "...oh, how much could that little thing cost"
Levers
Levers pull the cables that operate various systems of the motorcycle. If the ends are scuffed then you know that it has impacted something, probably lightly as they are the first to go in any fall. Good idea to have some spares on any long tour you may make. They should have some freeplay and not be bent. They usually snap if you try to straighten them.
Cables
When you pull the lever the cable should have a smooth action and return to its original position sharply. There should be freeplay at the control end of the cable. You shouldn't be able to see any broken strands of wire. You should see some sign that the owner has lubed it.
Cable Routing
The perfect routing for a cable would be a straight line. That is not possible on a motorcycle so as straight as you are able to make them is the rule. When inspecting the bike, turn the bars from side to side and make sure that the cables don't get pinched by the forks or pulled too tight at full lock. If a thottle cable gets pulled on when the bars are turned a certain way then you are an accident waiting to happen. Factory service manuals usually have several pages devoted to cable routing. Certain models of bikes may have different needs in terms of where the cable has to go to function correctly.
Sprockets
Sprockets are what the chain rides on to transfer the horsepower from the motor to the rear wheel. They have a given number of teeth which the chain engages with. You must look sideways at the sprocket and see if the teeth are hooked at all. They should be flat at the end...if they are sharp, then the sprocket is worn. The higher the horsepower of the bike then the faster the sprockets wear. If the sprocket is replaced then the chain should be replaced as well. Spinning the rear wheel backwards (elevated and by hand) you will hear the chain grabbing if there is any hooking.
Chain
When you inspect that potential purchase for chain wear you can look to see how far back the wheel has been adjusted to. If the adjusters are screwed in all the way, then it's a sure sign that the chain is totally worn. If the chain pulls back from the back of the rear sprocket then it worn.
Shaft Systems
The shaft drive system is almost maintenance free. At the rear axle you will see that oil goes in the rear housing. There is a large bolt in the top which, when removed, is where you pour in the oil. A smaller bolt on the side about half way up the housing is the level check. If you remove it then the oil should be at that level. There is another bolt at the bottom and that is the drain bolt. The oil used is a mineral based oil, Hypoid, and it has a unique odour to it. Don't use ordinary oil. You shouldn't have to worry about anything in this setup because it is rather bulletproof.
Shocks
The front suspension we have covered and the same theory applies to the rear suspension. There are two types... Dual shocks and Monoshock...
Monoshocks are not as easy to spot because they are tucked away in the guts of the bike. Look in front of the rear wheel and there should be a tube like cylinder running up to just under the front of the seat. It may be shrouded and all you can do would be to look for oil leakage in the area. The best test is to bounce the suspension and see how it reacts.
Dual shock types of suspension are totally visable and there will be one on each side of the bike, attaching the rear of the swingarm to the rear area of the frame, usually near the back of the seat. They should be straight, no oil leakage is supposted to be there. Once again the best test is to bounce the suspension and see how it reacts. (I will add to this in the near future
Swingarm
The swingarm holds the rear wheel and pivots up and down to allow for suspension travel. There is not much to go wrong with a swingarm except the side to side play it may develop. With the bike on the centerstand (or elevated) grab the swingarm and apply side to side force. If side to side play is found then you would have to tighten the swingarm nut. If it is already at the required torque then the swingarm bearing or bushings need to be replaced. This kind of job you may wish to pay a service shop to do for you.
More....
This is a very basic guide for those of you who don't know too much about bikes and I hope it has been of some use to you.