Used Bike Guide – Brakes/Clutch/Fuel Tank

Filed under: Buyers Guide |


• Put the bike in neutral. Roll the bike forward, gently apply the front brakes*. They should engage (and the lever should move) smoothly. (Though you may hear a click as the brake-light switch engages.) Now release the brake lever and roll the bike… Are the brakes off, or are they dragging? (They should be off.) If not, the brake calipers need work. Stand in front of the bike with the bike in neutral. Grab the front brake lever and squeeze it hard against the handlebar. As you’re doing this, try to drag the bike forward by the handlebars. (You may want someone behind the bike to stabilize it.) Do the brakes prevent the front wheel from moving? They should.
• *=If you squeeze the front brake lever and it comes all the way back to the bar without much resistance, something’s very wrong. Try adjusting the lever, if you know how (look for a little dial near the pivot). If this doesn’t fix it, or you have to pump the brakes a lot to get them to work, the system is either empty, full of air bubbles, or something is amiss in the master cylinder or caliper. Check to make sure that there’s adequate pad thickness, and make sure you get a professional mechanic to inspect the brakes before you try riding the bike. At the very least, the system needs to be bled. About £5 of brake fluid and half an hour of labor.
• Rear brake… roll the bike forward, use the rear brake to stop the bike. It should also engage smoothly. If the rear brake is a drum brake (no exposed brake rotor), is the wear indicator needle inside or outside the “usable range” indicator when the brakes are applied? Outside, of course, means the brakes are worn out.
• Some states have a mandatory safety inspection. If yours does, they’ll probably require that both front and back brake levers (separately and together) illuminate the brake light. If one does and the other doesn’t, you probably need a new switch (around £25?) or a switch adjustment. If both don’t, you probably just need a new bulb (around £1.)
• Check remaining brake pad material. There should be at least 1/8″ of brake pad material on each brake pad. For bikes with disc brakes, get in front of the bike and look into the calipers, on either side of the rotor(s). A flashlight might help here, even in daylight. The pads are the raised parts that directly contact the brake disc. If the bike has a disc brake in back, do the same type of inspection with the rear brake pads.
• Disc brakes continued: rotors should be a certain minimum thickness and shouldn’t vary more than a certain amount when spun. This kind of information will be in the service manual. As a general rule of thumb, rotors should be a minimum of 4mm, and warpage should be less than .012″. (FWIW, even warpage of .020″ probably won’t show up in the form of lever-pulsing at speeds below 45 mph.) If you don’t have the right tools to test this, you’ll probably need to rely on a test ride to spot a warped rotor — unless it’s so bad that you can see it with the naked eye. Even if you don’t have the right tools, you can inspect the rotors for cracks, deep wear grooves and other damage.
• Brake fluid should be a very light amber. Darker than honey means it’s time to replace the brake fluid. Not expensive, but possibly an indication that the owner hasn’t followed the maintenance schedule. (Or maybe the bike has just sat for a long time.) The front brake fluid colour and level should be easy to inspect through a sight glass in the front master cylinder or via marks on the translucent brake fluid reservoir. (Fluid level should be roughly in the middle of the sight glass or reservoir min/max range when the bike is on level ground and the steering is centered.) For bikes with disc brakes on the rear wheel, check the rear brake fluid as well — sometimes visible under the seat/tailsection, sometimes visible through a hole cut in the tailsection or side fairings.
• Inspect the brake hoses for nicks, cuts, dry-rot, and leaks.
• New brake pads are around £25-30 per pair (each caliper has one pair, so a bike with two brake rotors in front = two calipers up front = two pairs of pads up front.) Brake rotors are usually around £150-250 each. Brake lines are about £80-150 new, but if you have to replace them, replace them with braided stainless-steel lines, which cost a lot less (£70-80 new) and offer better brake feel and less heat-induced expansion.


• Ask the owner how many miles it’s been since the clutch cable was changed*. Owners who keep close tabs on bike maintenance will know. That’s a good sign. Most owners probably don’t know. If there’s a little slack in the clutch cable, and you can move the lever 5/8″ or an inch or so before the cable goes taut, that probably just means that the cable adjuster needs a turn or two.
• Put the bike in first gear, squeeze the clutch all the way in, roll it forward. It should feel like neutral, with possibly a little more resistance**. Slowly let the clutch out and feel for the friction zone. Clutch engagement should be fairly smooth, not abrupt. Put the bike back in neutral.
• If the bike has high miles (30k mi +) ask if the clutch has been changed. Only about £100 + 1 hour of labor, unless you need a new clutch basket, then maybe £300 + 2 hours of labor. (You won’t know until you get the clutch apart.)
• *=Some larger-bore bikes will have a hydraulic clutch instead of a cable-operated clutch. If this is the case, check fluid colour and level through the master cylinder’s sight glass. Fluid should be a very light amber, like the brake fluid, but both are pretty easy to change. The clutch master cylinder will be located on the left grip, much the way the front brake’s master cylinder is located on the right grip. Hydraulically-actuated clutches may or may not be “wet” clutches. A “wet” clutch is bathed in oil; a “dry” clutch is not. It’s hard to tell the difference just by looking at a bike, but as a general rule of thumb: Ducatis, BMWs and Moto-Guzzis use dry clutches, most other models use wet clutches.
• **=Wet clutches may tend to stick or drag a bit until the bike has warmed up and the clutch has spun a bit. This is often the case when the clutch hasn’t been used in a while. Wait until the bike has really warmed up before you dismiss a potential acquisition for having an overly-sticky clutch.

Fuel Tank

  • Look for: dents as noted above. Open it up, look for rust and/or loose sediment. Rust/sediment is bad — it clogs carburettors. Bikes with rusty tanks need to have the rust removed… drop the price £150 or so. You should open the tank up and see light-amber colored gas and bare metal. If you see a milky paint-like coating on the insides of the tank, the bike has had rust removed and the insides of the tank recoated. Make sure it runs — sometimes this recoating can clog the fuel’s path out of the tank. Many people swear by it, but I’d pay a little less for a bike with a tank that’s been recoated.
  • Exceptions: Some late-model bikes (e.g., recent Triumphs) have plastic gas tanks. It’s normal for plastic gas tanks to be milky-white on the inside. Knock on the side of the tank to see if it’s metal or plastic. Exceptions to exceptions: some bikes have metal tanks but have plastic tank covers, so when you knock on them, they’ll sound like plastic, but they aren’t. (Example: Yamaha FZR400’s.) Your best bet is to look closely at the inside of the tank — it should be fairly easy to tell whether or not you’re looking at metal or plastic. Evaluate the tank’s condition accordingly.
  • Dark (coffee or tea-colored) gas has been sitting around for a long time. Not a good sign. Get it changed immediately, and anticipate needing a thorough fuel-system cleaning. (Around £5 of parts plus 2-3 hours of labor.)
  • Make sure the lock in the gas cap is working. If it isn’t, it’ll probably cost £100-£200 to get a genuine OEM replacement cap with a lock that matches the ignition’s