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The front tire will usually not wear out, but if a rider does use the front brake aggressively, the
front tire will "cup" in the tread pattern. This is normal and will cause the tire to wander a little but
small raised areas can be removed with a wood file if they are causing a problem. The main
problem with tires will be cracking of the sidewall. If any cracking is observed, it is time to replace
the tire. A rear tire will wear more quickly than the front but will be subject to the same cupping as
the front, only in the opposite direction. Again, not a big problem, but may need some attention.
Tires can run anywhere from $120 to $350 a pair so new tires are a definite plus.
CHAIN/SPROCKETS
- Chains and sprockets are a high wear item and will cost from $100-$200.
As a chain wears, the small bearing surfaces inside the sideplates and rollers elongate while the
sprocket teeth open up. As the wear proceeds, the chain "stretches". The chain grows in length
because the individual link surfaces are wearing apart. Because the chain has a smaller bearing
surface than the sprocket, it wears a little faster than the sprocket. As the chain wears, it begins
to pull on only one link at a time rather than spreading out the force over several links. Thus, the
chain will wear out the sprockets. To check chain wear, grab the chain in the middle of the rear
sprocket and try to pull it outward. If you can pull the chain far enough away that you can see root
of the sprocket teeth, the chain is shot and ready for replacement. A chain should never be
replaced without also replacing sprockets. Beware of the "fixer-upper" who says that the original
chain was worn out, but he found a pretty good one on another bike and replaced it. Even a new
chain put on old sprockets will wear very quickly.
Even an old rusty chain can be squirted with oil so it looks pretty good, so don’t fully trust
appearances. When examining a bike, have your friend (the one you brought along) roll it along
for about 20 feet and look at the chain. There should be no dragging, binding or any evidence of
any links that are tight. This is another indication the chain must be replaced.
BRAKES
- If the front has disc brakes, shine the flashlight inside the caliper to look at the pads.
There is a groove in the pad that is a wear indicator. If the wear is down to the groove, it’s time to
replace pads. Some years have small inspection holes on the caliper with a little cover. This
cover can be opened up and the pads inspected.
Rear brakes are usually drum, so by looking at the adjustment nut on the brake arm you get a
good idea of how much brake shoe is left. Many years also have a small indicator arm and a cast
in area which shows the "good" area for brake wear. Personally I find it easier to just look at the
arm, although it is possible for a dishonest or inept owner to move the arm a notch on the brake
shaft.
Replacement of brake pads or shoes is something a home mechanic can readily do. Pads will be
about $20 per set and shoes around $30. If the bike has high miles and/or there is any evidence
of brake fluid seepage, the caliper should be rebuilt. This is something you may want to have a
shop do so figure the shop labor rate accordingly.
BATTERY
- I don't think I have ever bought a 650 with a good battery. If you find one with a new
battery, great! However, the battery deserves some attention. If the bike has a battery installed,
remove the cover and cables and lift it out of the battery compartment. Take a look down inside
and see how much rust there is. Also look over the battery for any cracks or holes. If it is full of
fluid, it may be sulfated (which is seen as a white deposit on the inside of the battery) which
means it will not hold a charge. The reason holes in the battery are important is that this has
allowed the acid to run down on the inside the frame and is slowly eating away at paint and metal.
As batteries lose their charge they also freeze at a higher temperature. When they freeze, the
fluid expands and cracks the case. If the batter has leaked on the bike, it will need a thorough
cleaning with a solution of baking soda and water to neutralize the acid. When the baking soda
hits acid it will foam, so you will know when it has all been neutralized, then rinse with clean
water. Any rust spots should be sanded and painted. Plan on $30 to $50 for a new battery.
