Preparation
The first thing to do is to check
that everything is working BEFORE you get to the track, preferably,
on a stand in your garage.
Safety
NEVER, NEVER, NEVER try starting
the kart by putting a rope/strap round the tyre and pulling. It
MAY work but it MAY also KILL YOU. The end of the rope can get caught
in the chain/axle or whatever and it will 'reel you in' and cut
you to ribbons. If you're lucky, you'll just lose a hand or an arm,
if you're not..……………………..
Spark Plug
Remove the plug and reconnect
it to the plug lead. Lay the plug on TOP of the engine (preferably,
with the sparking end AWAY from the plug hole as it can ignite any
fuel in there; it may be fun but it’s not too clever!). You
MUST make sure that the metal of the spark plug makes good contact
with the main metal of engine whenever you spin the wheels or you
can damage the ignition system. Now spin the rear wheels and you
should see a healthy (fat) spark. If it looks feeble, buy a new
plug.
Check the spark plug is clean
and not 'wet' (oily or dripping fuel). The ideal colour is from
'brand new' to mid-brown. Black is OK but it's better to get a wire
brush and clean it up. If it's caked in rubbish of any colour (a
bit like the 'fur' in the kettle), clean it or chuck it!
If you don't get a 'fat' spark
even with a new plug, your ignition system has a problem and it's
NEVER going to run without skilled help.
Remember what the clean, dry plug
looks like as this comes into play when we get to the 'starting'
part of this article.
Fuel System
Your carburettor has an inbuilt
fuel pump. The action of turning the motor causes the pressure to
rise and fall inside the crankcase. There is a connection between
your crankcase and the carburettor (a tube or a drill hole in the
rear of the carburettor) that uses those changes in pressure to
pump the fuel. Many things can fail in a carburettor but they can
all be fixed. The simplest test is to check that the fuel pump is
pumping! Remove the spark plug, reconnect the plug lead and make
sure the plug makes good contact with the cylinder head. Now, place
the flat of your hand over the air intake (at home, it's easier
with the air box removed), open the throttle FULLY and spin the
wheels quite briskly. You should now see fuel moving up the pipe
to the carburettor. What's happening is that an engine is really
an 'air-pump'; when you turn it, air goes in through the carburettor
and out the exhaust. By blocking the air intake, you are preventing
the air getting in and the pressure inside the carburettor drops
and that ‘sucks’ the fuel in. You MUST open the throttle
or this 'choking' trick DOES NOTHING AT ALL (many people don't know
that!)! This is because the main fuel inlet is on the 'other side'
of the 'throttle'. So, if it's not open, it DOESN'T ‘suck’
the fuel in!
If fuel doesn't come up, you need to check that all the fuel lines
from the tank to the carburettor are connected properly. If the
pipe/s are too stiff, they can let air in and stop the fuel from
moving. Buy good quality fuel lines. Un-leaded fuel is really aggressive
stuff and pipes harden very quickly if you leave it in the pipes
after driving the kart. It’s a good idea to empty the fuel
pipe as much as possible after each race/practice day. The pipe
will last much longer this way.
Once you've got the fuel up to
the carburettor, you can check if the fuel pump is working. Take
your hand off the air intake and spin the wheels again. You should
be able to see the fuel 'moving' very slightly in the fuel pipe.
This is the action of the pump on the fuel, not the 'choking' reaction.
It's not a problem if there are small bubbles (up to about 1cm)
in the fuel line as this is quite normal. In some ways, they are
quite an advantage as you can see what's going on with the fuel.
You may need to use the 'choking' method BEFORE you can test the
pump. To work properly, the pump should have fuel all the way up
to (or very near to) the carburettor. If you have not 'choked' the
fuel all the way to the carburettor, the fairly feeble pumping may
not be strong enough to overcome the air
inside the fuel pipe.
This is a LONG explanation; but
there are many other things that can still be 'wrong' even if everything
checks out perfectly up to this point. But, if you have a FAT spark
and fuel up to the carburettor, you are 90% of the way there.
Starting the Kart at the
Track
Starting is all about getting
the kart moving forward and KEEPING it moving forward until it's
able to accelerate way on its own.
To make life easier, make sure
everything is ready BEFORE you start pushing. You will have checked
the spark is good and ‘fat’ and that the fuel is getting
to the carburettor BEFORE getting to the track. Now make life easier
by getting the fuel up to the carburettor BEFORE you start pushing.
You can do this by 'rocking' the rear wheels back and forth while
'choking' (as discussed before). DO NOT MAKE THE ENGINE TURN OVER
BY HAND; it may well START and trap your hands! You can do this
while sitting in the seat or with the kart on the stand. Once the
fuel is up and ready, we're nearly ready to push the kart.
There are two basic methods:
1) Driver Seated
2) Driver Running!
DRIVER
SEATED
Lucky (or rich drivers) have
two pushers, but one is plenty, if he is reasonably fit and sensible
and he really does not need to be an ‘Arnold Schwarzeneggar’!
There’s no way round it, the angle and the task is not good
for the pusher’s back; those with troubled backs or hernias
should NOT apply! It’s also a good idea for the pusher to
do a few backstretches before he goes for each new attempt.
Firstly, get the driver to lean
right OVER the steering wheel. The driver should attempt to grab
the FRONT bumper! This moves the weight forward and makes the pusher's
job MUCH easier. You can improve on this if the driver sits on the
front EDGE of the seat as well as leaning over. It makes the kart
'feel' about HALF the weight to the pushers and this is VERY worthwhile
Lifting
The driver should also try this
bit so he can see that the pushers have to do. It's all about getting
your bum as LOW as possible.
The Wrong Way
With a driver seated, try placing
your feet so that both of your legs just touching the rear bumper
and both hands are on the bumper and then lift the kart. You'll
find that you can only move very slowly forward in small steps as
you keep banging your ankles on the bumper. You'll also notice that
the pusher's centre of gravity is almost over the rear bumper. This
is OBVIOUSLY the wrong way to do it! However, this is exactly what
all beginners do; hence their problems starting the kart!
The Right Way
With a driver seated, stand with
your RIGHT foot under the rear bumper and your LEFT foot about 3/4s
of a metre back. Place your right hand on the bumper (to lift it)
and your LEFT hand on the back of the seat, just to steady yourself.
You'll only be lifting the kart with your RIGHT hand. You'll now
notice that your bum is MUCH lower than before and that you don't
bang your ankles on the bumper. Ideally, the pushers want to look
as HIGH into the sky as possible by 'craning' their necks back as
far as they can go! The pushers **** MUST NOT **** look down at
the kart or the track! You'll notice that, the higher the pusher
looks:
1) the lower their bums are
2) the further back they will have moved their left foot .
3) the further back their centre of gravity has moved
This will allow them NOT to fall
over when they have started the kart; more about this later. KEEP
THEM LOOKING UP!
Oddly enough, when you get used
to this, you'll find that you lean DOWN with the LEFT hand on the
back of the seat while you are LIFTING the kart with your RIGHT
hand. This lets the pusher’s Centre of Gravity even further
back and leaning forward on the back of the seat (with the left
hand) is the start of the PUSHING action
Lift and Push
An engine does not want to turn
over as the compression is holding the piston 'back'. We lift the
kart so we can get some forward momentum that will be enough to
overcome the compression resistance. We don't have to move very
far forward before we hit the ground as a walking pace is enough
to do the job of overcoming the initial resistance! Similarly, we
don't need to lift it very high, just enough to get the kart moving
without the friction of the rear wheels. About 5 cm is the MAXIMUM
you need to lift. Any more than that and the nose cone will be rubbing
on the ground, which makes it harder.
The first part of the pusher's
job is to lift the kart, move forward about 1 metre and then PUSH
it down and forward onto the track. They should be prepared to CONTINUE
pushing for a good few metres; their job has not finished……..
YET!
Now for the driver! Engines need
a mixture of Fuel and Air at a specific ratio to run. The colder
the air (and the engine) the MORE fuel is needed in that ratio.
Stone cold engines on a cold day need MUCH more fuel in the mixture
than hot engines on a hot day. Older cars were fitted with a Choke
Knob or Lever to adjust this ratio, nowadays, that ‘choke’
is automatic. Karts don't have automatic chokes (most don't have
ANY sort of choke!) so you need to be your OWN choke. It's as the
name implies, you are trying to STRANGLE (choke!) the engine by
cutting off its air supply. You do this by placing the FLAT of your
hand over the air intake. What happens is that the air can't get
in so any 'suction' inside the carburettor pulls in extra fuel instead.
Remember to open the throttle FULLY or choking is a complete waste
of time!
Just before the pushers start
their work you should have your hand OVER the air intake but NOT
actually closing the intake off just yet. I just rest my fingers
on the casing/airbox so that I can choke if I need to without frantically
searching for the opening. Once you're helmeted and seated, it can
be hard to find the air intake in a hurry, so: Be Prepared!.
As the kart hits the ground, slide
back into a proper seating position. You will have previously warned
the pushers to move their hand AWAY from the back of the seat once
the kart has hit the ground or your will TRAP them as you sit back!
If they get trapped, you will drag them along the pit lane, not
too much fun that! Get them to transfer their hands (smoothly) to
your shoulders and KEEP pushing and KEEP LOOKING UP!!!!!!! Make
their job easier by not leaning QUITE ALL the way back; if they've
forgotten about getting trapped, you have allowed them some freedom
to escape.
The driver’s work starts
here! It’s highly possible that you won’t need any choke
and that choking at all will stall the engine. It’s also highly
possible that it will need a LOT of choking. You will gain experience
and be able to judge this for you self with practice. However, as
a beginner it’s worth getting into a routine based on the
distance that you have been pushed!
1) 0 to 5 metres
Don’t Choke. Just start increasing the throttle setting, (if
it fires, go to point 4)
2) 6 to 30 metres
Go to full choke (hand firmly over the intake) and FULL THROTTLE,
if it fires, lift your hand away from the intake but keep it hovering
over the intake just in case it stalls again. (If it fires, go to
point 4)
3) 31 metres onward
If your pusher is still going, take your hand away from the inlet
(but ‘hover’) and give FULL THROTTLE. If you have prepared
as discussed and you have been choking for 30 metres, it’s
more than likely that the engine is now flooded rather than being
starved of fuel. Full throttle will allow the engine to dry out
a little and it may fire IF your pusher can keep going! (If it fires
go to point 4).
4) The engine fires
Once it fires, lift your hand a SHORT distance away from the air
intake so as to let in unrestricted air but still with your hand
‘hovering’, to be ready to apply full choke if the engine
tries to stall as it may WELL do! If you've put your hand back on
the steering, wheel it's much more of a game to re-find the air
intake before it stalls.
Obviously, when it starts to
fire, you will 'un-choke' (if you have been) and you should also
REDUCE the throttle position. It is WRONG to accelerate away at
FULL throttle within the pits! Out on the track, it's OK if it's
safe (no pushers ahead of you) but that happens all too rarely!
It's also a very clear sign of lack of mechanical sympathy. Anyone
who accelerates an engine (cold OR hot) to full throttle and full
revs immediately after starting shows they do not understand ANYTHING
about engines! If you see people do this, simply think "IMBECILE!".
The list of disasters that can go wrong by abusing your engine in
this way is longer than this article!
Remember! Be Prepared! The engine
may well try to stall, just put your hand back over the intake and
go to full throttle again.
This is why the pushers MUST keep
pushing until they can't stay with you! Many engines will stall
even after they have started and a 'dead' kart in the middle of
the starting straight is NOT much fun for those trying to start
their karts behind you. You will find that many karters behind you
are looking back at their carburettor as they start their engines
and they will drive straight INTO your stationary kart! (I can never
imagine what they hope to see back there! Drivers: keep looking
FORWARD!) If your pushers are still behind you, the following karts
crush your pusher's ankles against your rear bumper; NICE! Tell
your pushers they MUST, MUST, MUST KEEP RUNNING once you have started
and to CHECK behind them as they RUN off the side of the track/pit
lane! All this is just common sense but you would not BELIEVE how
RARE that is on a kart track!
As the kart starts, the point
of your pushers having a ‘low bum’ and their Centre
of Gravity as far back as possible comes into play. If they are
looking down, with both feet together, they will FALL OVER when
the kart starts! If they are looking at the sky, they will be able
to stand up and keep running!! The choice is theirs!
If there are only two of you,
your pusher MAY not have enough strength to lift and push you. It's
not that hard once you've practiced but may well be completely beyond
a beginner. There are many alternatives:-
Easy Start Wheels
Kart shops sell all sorts of
easy starting tools from long handles levers with wheels to things
that look like tall skinny roller skates. You use these to hold
the kart off the ground while the pusher gets up to speed and then
'drops' the kart onto the track and carries on pushing. Of the two,
I prefer the short roller skate type but, as a first choice, I’d
go for the old-fashioned un-assisted lift and push even though I'm
50 years old (and fat)!
You can buy a device that bolts
a single 'additional wheel on a lever' onto the underside of the
kart. You lock it into position, push the kart and then release
the lock, which collapses the wheel out of the way. These are great
but they add weight. They also make one more thing that can go wrong
on the kart! However, they do allow the driver to ‘trundle’
the kart back to the pits if it fails on the circuit.
DRIVER
RUNNING
This is the MOST 'professional'
way! Assuming there are two of you, the pusher does exactly as before
but the driver stands on the RIGHT hand side of the kart with his
LEFT hand on the rear of the seat and the RIGHT hand on the top
of the wheel. The pusher does exactly the same as with the driver
seated but he now has almost no weight to lift. Once the kart is
'airborne' and moving forwards, the pusher and the driver MUST push
down to stop the wheels from skidding as it hits the ground. As
before, the pusher KEEPS PUSHING!
The driver runs with the kart
for about 3 metres and then swings himself into position and this
should be practiced first ON YOUR OWN with the kart stationary.
The driver is trying to lift himself into the kart by supporting
his weight on the top of the wheel and the back of the seat. The
driver then swings himself into the kart so that his RIGHT foot
lands just behind the throttle peddle and the LEFT foot lands in
the centre of the seat AT THE SAME MOMENT! Bring the LEFT hand to
the wheel and get your LEFT foot behind the brake pedal while sitting
down. (The kart WILL start whether you have your foot near the brake
pedal or not; it's up to you how important this is to you. Think
of the implications if the throttle is stuck wide open and you don't
have your foot near the brake!). Your RIGHT hand now goes to the
'Hovering Choke' position.
It all sounds REALLY complicated
but it isn't! Practice with a stationary kart until you can easily
swing yourself in. Then try with it with your pusher but with the
spark plug out (but 'strapped' to the top of the engine). This will
make sure it won't start and there will be little or no rolling
resistance. You can obviously do this on your driveway or down the
pavement if the plug is out! You can even do this on your own (with
the plug out) and you will be shocked how simple it all is! The
first few times can be embarrassing as you accidentally turn the
steering wheel and run over your foot but you’ll get the hang
of it very quickly.
As I said, this is the professional
method. If you master this technique, you don't NEED a pusher because
you can do it all on your own! It's not so important IN the pits
but it WILL get you going again out on the track once you have spun
off! You'll find you don't need to LIFT the kart right off the ground,
just slightly release the weight (by pulling the seat upward) and
you can simply SLIDE it before you push it DOWN to turn the motor
over. Once it's moving along quickly, you can jump in but you must
get to the throttle pedal quickly to get you going. The engine will
probably be warm and should start without choke!
What to do if it doesn't
start after a 'good' push?
There are usually two possible
reasons (assuming everything else checked out properly, earlier).
Either, you have choked too little or you have chokes too MUCH!
If you can see fuel dripping out
of the carburettor or air box, obviously, you've choked too much!
However, it may not be visible. You can get over this by pushing
it again with NO CHOKING BUT FULL THROTTLE! It may well start as
the engine is, in effect, fully choked already! However, it may
be too flooded (over choked) to start.
You can check if it's flooded
or not by removing the spark plug and looking at it. If it's wet
and/or oily, you've choked too much. If it's dry, .... well do I
need to tell you? Please do this checking IN YOUR PIT BAY! The reason
is simply SAFETY. If you are on the side of the track with 1 or
two pushers fiddling with the spark plugs, there is a GOOD chance
someone will crash into you! A dry plug tells you try again but
choke and push for longer! How far should you push? Until your pushers
drop in a small heap! I have done well over 100 metres as a solo
pusher and managed to get it going in the end!
A wet plug means that you need
to dry it and get rid of the excess fuel in the engine. Firstly,
put the kart back on the stand and clean and dry the plug. A spray
can of 'EASY START' (yellow and black spray can of almost pure ether;
any car spares shop sells it) does the job VERY well. This washes
the oil out of the plug. A small wire brush will clean up the plug
nicely. Plugs DO fail and it’s well worth buying the CORRECT
plug for the weather conditions; ask your kart shop for the right
plug for the conditions. A wrong plug on the wrong day can melt
the piston so GET IT RIGHT!
If the plug was VERY wet and oily,
the inside of the engine will also be very wet and it's a good idea
to dry it out as much as possible. You can do this by rapidly spinning
the rear wheels with the plug out (but connected!) and the throttle
fully open. If it's very wet, you will see plumes of oil/petrol
spray ejected from the plug hole; GOOD! Do use some sense about
smoking near this little lot!
Now put the plug back and start
again.
As a last resort before abandoning
the project, try to borrow a spark plug that's still HOT from being
run in another kart. That little bit of heat can make the difference.
Once it's running (one or two laps), come back to the pits and change
back to your own plug! Be careful when handling HOT plugs, they
will burn if you’re not careful
That's about it! Other problems
may still prevent it starting but that will indicate a mechanical
failure somewhere and that is probably going to need professional
help.
Summary
Mechanic
Check Fuel and Spark before going to the track
Get fuel up to Carb before getting ready to push
Pushers
Do some back-warming exercises
Stand with one foot forward and one back while looking UP as high
as you can
Right hand on bumper, left hand on seat back
Lift 5cms up and carry for 1 metre
Pushdown and KEEP PUSHING and KEEP LOOKING UP.
Don’t let the driver trap your hand in the seat
When the kart start, KEEP RUNNING and checking behind you until
you get off the track
Drivers
Lean forward over the steering wheel
‘Hover’ your hand over inlet
Once rolling, sit back in the seat (but let pushers ‘escape’)
Until the engine fires
0-5 metres no choke, slight throttle setting
6-30 metres, full choke and FULL throttle
30+ metres, no choke but FULL throttle
Once it fires, REDUCE THROTTLE but ‘hover’ hand over
the inlet!
Ian Turner (ITPRO)
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