WORKBENCH
By Michael R oss
WHENWINNING
Diamonds and rust
here are few things that you can do
to a motorcycle that are worse than
letting it sit. Many prospective buyers
go loo king for a used motorcycle and often
times find one tha t looks like a jewel and
· is low mileage because the owner never
rode it and he is now selling to clear ou t
his garage. Caveat emp tor. Undernea th
that shi ny exterior may be a host of
pro blems that Can be difficult and expensive to fix.
When motorcycles sit dorm ant for over
"a year the gasoline turn s to an awful
smelli ng, green ish brown goo tha t defies
removal by even the most caustic of
carburetor cleaners. And when you consider that some passageways in the carb
are often little bigger than the diameter
of a human hair, you will understand why
getting them to flow fuel in the proper
ratio again is a dau nti ng task at best. I
have tried everything from carbonic acid
to u ltra-soni c cleaners and still met with
poor results. Sometimes the only alternative is to replace the whole carb body; not
a very desireable alternative for the owner
who bou ght used to save some bucks.
Ano ther probl em peculiar to bikes that
sit for years at a time is a rusty fuel tank.
The fine, almost microscopic rust flakes
that form at the bottom of the tank from
water that condenses out of the air in a
partia lly filled tank will clog jets and stick
needle valves open until the tan k is cleaned
wit h acid and coa ted with a special
preparation that covers the rust spots an d .
stops the forma tion of more. BMW is the
onl y manufacturer I know that coa ts the
inside of their tanks when new. Rust inside
of Beemer tanks is almos t unknown for
this reason. In fact, if you have a bike that
sits period ically it is a good idea to have
the tank coated before the need arises.
~ The most debilita ting prob lem that
arises from letting a bike sit is the loss
off piston ring seat. It doesn't take long
rfor the oil to drai n off the cylinder walls ,
allowing hum idity in the air to start
· rusti ng the piston rings where they contact
the cylinder wall. T he rings are now pitted
l and the cylinde r wall has a rust ring
. aro und its circum ference that is impossibl e
to remove witho ut boring.
T his condi tion usua lly mani fests itself
in sub tle ways. T he bike in question seems
)wC' and the plugs are prone to fou ling.
ak
.It may smo ke on start up or when the
engi ne is ru n hard. I have taken apart
engi nes with this condi tion that had ru st
pits on the cylinder walls so deep that
bori ng them to the last oversize (.04
