MINSK Repair Manual page 23

Cleaning the carburettor is not as difficult as it sounds as most of the parts in it
have non-uniform shapes which can't be put back together the wrong way. All you
need is a #13 spanner, a flat screwdriver, a thin strand of electrical wire, a clean
rag and a pair of pliers.
As there are two kinds of carburettors found on Minsks, I'll make a description
for both. The smaller, rounder, screw-top version is much more straight-forward
on the inside and cleaning it is easier as you can use your eyes to see if the jets are
blocked. It is also more fuel efficient, more expensive and causes the bike to drive
a little slower at top speeds. The taller, rectangular shaped one has more bits on
the inside but the mechanics are essentially the same. The bulk of the following
description is based on the rectangular version with small annotations made where
necessary for the rounder carburettor.
First pour a little petrol onto the carburettor's exterior and wipe all the grime
off. Do the same for your hands. The rubber seal connecting the rear of the
carburettor to the air box can be turned inside out – or folded back onto itself. Use
your screw driver to do this. Pull off the tube coming from the petrol tank.
Remove the two #13 screws connecting the carburettor to the engine and then pull
it off the two threads attached to the engine. The best way to remove the
carburettor is to rest your chest on the seat and with one arm on either side of the
bike, come at the carburettor from above. You will have to push the carburettor
back into the air box to get it off the screw threads coming out of the engine. You
have to push hard so persevere if you have a hard time.
Once removed, unscrew the two screws at the top of the rectangular
carburettor and pull out the brass gate, pin and spring. Be careful not to let the
spring and gate become unattached to each other as getting them back together
correctly takes time. The process is simpler with the round carburettor as the
round lid can be unscrewed by hand.
Now the carburettor is completely disconnected from the bike. Hold the body
of the carburettor in the palm of your hand and unscrew the two (if it is the
rectangular version) or four (if it is the round version) screws holding the bottom
section of the carburettor on. The bottom of the carburettor, which is in fact the
sump, will then fall into your hand and give you access to everything inside. Look
for dirt residue and balls of water at the bottom of the sump under the petrol. If
there is any gunk then get rid of it.
Then blow through both brass coloured jets to clear any remaining petrol in
them. Also ensure that they are screwed down tightly. Then point the top end of
the carburettor to a light source and look down both jets to see if the holes are
clear of residue. If blocked then try to blow the gunk out or alternatively use a
single thread of electrical wire to do the job. Blow hard into every hole that you
see on the inside of the carburettor. Also blow into the outside hole where the
petrol tube is normally fitted and ensure that this is not possible when the stopping
pin attached to the float is in its top most position.
Check that the float tank can move up and down easily, that there is no liquid
in either of its two tanks and that the tiny plastic washer seal on the stopping pin is
©Digby Greenhalgh 2000
Minsk Repair Manual
20