Radne Raket 85 User manual

Radne Motor AB
Users
Manual
English

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Users Manual
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© Radne Motor AB 1998-2005
Introduction
We at Radne Motor congratulate you to your choice of the Raket
85 go-kart engine.
With this manual we will try to give you hints regarding the run-
ning and the maintenance of your new engine. It is our sincere
hope that your new engine will give you lots of fun and very few
problems.
If you follow our simple instructions in this manual you can avoid
many costly mistakes.
We recommend you to read the complete manual, even if you are
an experienced go-kart mechanic.
You can still pick up a few things on how to maintain and service
the engine.
You can always find an updated version on this manual or other
things that could be of interest at our Raket website: http://www.
radne.se/raket/
Radne Motor AB
Radne Motor AB was founded in 1967 by Leif Radne to produce
and sell engines and parts for go-kart. Today almost 40 years later
it is still main business concept of the company
We have now expanded our range of products to include pa-
raglider engines.
Radne Motor is one of the major go-kart engine producers in the
world, and exports the range of engines to more than 60 coun-
tries.
Radne Motor AB
Box 3035
S-136 03 Haninge
Sweden
Tel: [phone]
Fax: [phone]
e-mail: [email protected]
home page: www.radne.se
Rev 1, 2005-01-14

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Raket 60
Raket 85 Racing
Raket 120 Racing ES
Raket 120
Raket 120 Aero ES
Raket engines
The first Raket engine was introduced in 1972. Extensive re-
search for a reliable, simple to use, yet fun to drive go-kart engine
at an acceptable price, had convinced Radne Motor to start the
manufacture of such an engine. Power chain saw engines are the
toughest two stroke engines that are built, and Radne Motor de-
cided to build the go-kart engine on well-tested vital parts. Hence,
cylinder and piston, crankshaft, carburettor and ignition system
were purchased. Radne Motor manufactured other parts that are
typical for a go-kart engine, like the aluminium crankcase. Finally,
the engine was assembled and tested by Radne Motor before it
was shipped. All Raket engines have been built around this con-
cept, which has proven to be very successful.
Today the Raket line of engines consist of:
Raket 60 for the very young drivers. This engine has rope start,
centrifugal clutch and forced air cooling. It can be equipped with
catalytic emission control and a rev. limiter.
Raket 85 is the most popular and most produced Raket engine. It
is used in many countries for the youngest drivers. Often the same
engine is used with some type of power restrictor for the youngest,
and later, with the restrictor removed, for the more professional
drivers. The Raket 85 engine has a whole series of extras and
conversion kits, so it can be used also for indoor driving and for
rental kart use.
Raket 120 is used mainly for Ultra Light Aircraft, so called Para-
gliders. This engine is extremely powerful for its low weight.
But Raket 120 has found many more uses, both for go-kart and
where the low weight in combination with high power and good
reliability is appreciated.
Spare parts and service for the Raket engines are available from
Radne Motor or from our distributors. We recommend that you
consult our catalogue. A new catalogue is produced every year,
in which you find the latest parts and also hints for the best use of
your Raket engine.

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To the new owner of a Raket 85
kart engine
Please read the following two pages. It will take you perhaps 15
minutes, but it can save you a lot of aggravation and money in the
future.
We congratulate you to your new Raket 85 engine. We hope you
will have a lot of fun with it.
This engine is especially developed for the two junior classes
Micro and Mini, for drivers 10-12 and 12-15 years of age.
When you read the following pages you will find numbers that
refer to the exploded view on page 19. Numbers in the text with
six digits are spare part number engraved into the part in question.
All four digit numbers are our own part numbers. See the spare
parts list on page 18.

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Mounting the engine on the kart
For this purpose use original engine mount for the kart.
We have a special engine mount for the Raket 85 engine,
which makes the mounting to the frame very simple. The
part number for the engine mount is 3004. Please see illus-
tration for drilling instructions.
When you have mounted the engine to the frame, you must
link the carburettor with the accelerator. We have made a
special throttle linkage (no 3083), which makes it easy to do
this. We recommend that you have an extra return spring
that helps to close the throttle, in order to make sure that
the throttle closes every time you release the accelerator.
Finally, you connect the fuel hose to the carburettor. Use a
transparent, flexible hose with an inner diameter of 6 mm.
Flexible hose and muffler
Note!
Check that the flexible exhaust hose tightly surrounds the
beginning of the conical part of the muffler. This is very
important!
The Raket 85 kart engine is homologated with the muffler 3012 in
the Mini class, and with the muffler 3140 in the Micro class.
Between the muffler 3012 and the exhaust pipe 3132, you must
use a flexible hose (our number 3010). The length of this flexible
metal hose is important. One part of adjusting and tuning your kart
to a new track is to try out a suitable length of this flexible hose.
The principle is that the longer you make the hose, the stronger
the engine will be at low revs. And, the shorter you
make the hose, the higher the engine will rev up.
You should start with a standard length of 660 mm,
see illustration, and then try out the most suitable
length.
This is how you measure the length:
Measure from the gasket (3053) between the cylin-
der and the exhaust pipe, along the exhaust pipe, the flexible hose
and the muffler (that is the length along the outside).
If you want to change the total length, simply change the length of
the flexible hose.
51
102
80

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Carburettor setting
If you mounted the engine on the kart according to the description,
you are now ready for your first test run. Select a “normal” gear-
ing. We suggest 11 teeth on the engine sprocket (this is standard)
and 80 teeth on the rear axle sprocket, this we call 11:80 gearing.
Grease the chain with special chain grease, and don’t forget to
mount the protection over chain and sprockets.
Allways use inlet silencer to lower the noice and protect the en-
gine from dirt.
Now let us make the basic setting of the carburettor:
Turn both the fuel needles (marked L for Low rev mixture and H
for High rev mixture) gently clockwise until you feel that they bot-
tom.
Now open (anti clockwise) the H needle 1 turn and the L needle 1
turn.
This is the basic setting, and we guarantee that you can run the
engine with this setting as long as you practice to get used to
the engine and the kart. You can lower your lap times with some
tenths of a second if you screw the H needle clockwise (this gives
leaner fuel mixture) – BUT YOU MUST NEVER CLOSE IT MORE
THAN TO ½ A TURN OPEN. If you close the H needle, you MUST
open the L needle to enrich the mixture at low revs,
Let us say L needle will be 2.5 full turns open. The correct set-
ting of the two needles is one of the secrets of the successful kart
mechanics, but here are some hints:
Look at the sparkplug. It is white, the mixture is too lean. If it is
black or wet, the mixture is too rich. Correct setting shows a light
brownish color of the sparkplug electrode.
If the H needle is correctly set, you will notice that the engine goes
over in 4-stroke just at the end of the longest straight.
If the L needle is correctly set, the engine will respond immediately
when you push the accelerator after you have had it released (e.g.
after a sharp bend).

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The best advice we can give you, and this can save you a lot of
money, is that you take advice from someone who has experience
of the Raket engine BEFORE you try some extreme carburet-
tor settings. No engine has taken serious damage of a too rich
mixture, but many, many have broken down because of too lean
mixture.
Fuel
The Raket engine works well on unleaded fuel, but we recom-
mend 98 octanes, with a 5 per cent mix of 2-stroke oil. We don’t
recommend the use of so called outboard oil. The engine can also
run on 2- stroke oil intended for extremely low mixture, normally 1
per cent. But, if you use such oil, you must be very careful when
you mix fuel and oil. This is the reason why we recommend this
type of oil only if you get it in small packages ready to be mixed
with 5 or 20 liters of fuel. Ready-to-use oil in such small packages
is available for the Raket engine from Radne Motor.
Driving under rainy conditions
When driving under rainy conditions it is absolutely necessary to
protect the carburettor from water splashes and water mist. If too
much water is allowed to enter the engine, very serious engine
damages, e.g. on cylinder and piston, can occur.

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Service advice
If you are not satisfied with the performance of the engine, and
other karts are faster down the straight or out of the bends, it does
not necessarily mean that your engine is no good. It could mean
that it needs basic adjustment of the carburettor or ignition sys-
tem. Of course, the piston or the piston rings could be worn out,
the radial sealing rings could be leaking or a bearing on the crank-
shaft could be worn out. But more likely, the difference between a
good engine and a tired one is found either in the carburettor or in
the ignition system.
So here are some hints on how to check and adjust the carburet-
tor and the ignition system.
The carburettor used on the Raket 85 engine is a membrane car-
burettor with a built-in fuel pump. It is made by Tillotson in Ireland,
and has the designation HS. If we follow the gasoline through the
carburettor it is easy to explain the function of the carburettor. The
carburettor has two covers, one is made of steel and the other is
made in aluminum casting. Under the aluminum cover is found
a rubber membrane, called the pump membrane, and a gasket,
on each side of the membrane is a small chamber. One of these
is directly connected to the crankcase with a channel. When the
pressure in the crankcase varies, it will move the pump mem-
brane up and down. On the other side of the membrane, in the
other chamber, is the fuel. When the membrane moves, it pumps
gasoline in and out of the chamber. Two small valves are punched
out from the same piece of rubber as the pump membrane, and
they now act so that fuel is sucked from the fuel tank and pumped
into the main carburettor. The pump shall give a pressure of 0,5
kp/cm2. It is very easy to check if the pump is working. Unscrew
the sparkplug to make it easier to rotate the engine. Check that
the fuel hose is connected correctly and that the carburettor is
mounted correctly on the engine. Check all gaskets, especially
the gasket between carburettor and the engine so that there is no
leaking, or is blocking the channel. Then push down carefully the
main membrane with a small screwdriver through the little hole in
the punched steel cover of the carburettor. This will open the fuel
inlet needle valve.
Now rotate the engine, and check through the transparent fuel
hose if fuel is flowing from the tank to the carburettor. If it is not,
push down the main membrane, loosen the fuel hose at the tank
end, and blow carefully into the free end of the hose. You shall
be able to blow slowly through the hose and the carburettor. If
you can’t, take away the aluminum cover and check the small
fuel filter (no 43 on the spare part list) – it could be blocked. After
that, check the pump membrane – it can be broken. That can be

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very hard to see, so if it has been used for some time – change
it. When you change the pump membrane, always change the
gasket too. The membrane shall always be placed nearest to the
carburettor housing, otherwise the valves will not work. Then take
a last check of the channel between the crankcase and the carbu-
rettor.
Now check the pumping action again. If it still doesn’t work, check
the needle valve (see below) in the carburettor, which could be
stuck. The pump pushes fuel towards the needle valve, but can’t
open it. Let us look at the other side of the carburettor. If you take
off the steel cover you will find another membrane, a lever with
a spring and a needle valve. The needle valve is held in closed
position by the spring working through the lever. The lever rests
against the main membrane (which can be recognized by the
small rivet in the middle of the membrane). The lower side of the
main membrane and a cavity of the carburettor housing form a
small fuel reservoir. When air is rushing through the carburettor,
the fuel under the main membrane is sucked out. The fuel lever
under the main membrane is now reduced. The membrane is
moving downwards and forces the lever to open the needle valve.
Now more fuel comes in from the pump side of the carburettor.
The membrane moves upwards and the lever can close the valve.
This is how the carburettor keeps a steady level of fuel.
From the chamber under the membrane the fuel goes through the
H and L needle valves to the venturi of the carburettor. The chan-
nels are so thin that the fuel does not pass through unless it is
sucked. The design and location of the small holes through which
the fuel can enter into the venturi are of great importance for the
characteristic of the carburettor.
Now for some service hints. Let start with the needle valve. First
take off the steel cover and the main membrane with its gasket.
Then loosen the little screw under the membrane. Now it is pos-
sible to dismount the needle valve. Don’t loose the spring.
Check the needle valve. The conical rubber end must be smooth.
If you can see impressions – change the valve. Check the bot-
tom of the hole that the needle valve is sitting in. It shall also be
smooth. When you have cleaned everything, start to assemble
the needle valve with its lever and spring. The spring and the
lever must not be deformed (you shall have some as spare parts).
When you have assembled the needle valve, the arm of the lever
that is in contact with the membrane shall be at the same level as
the adjacent level of the carburettor.

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How to check the correct opening pressure for the needle
valve.
Connect a small air pump with a manometer to the fuel nipple of
the carburettor. Drop some fuel on the needle valve and pump up
some pressure. At 1.0 kp/cm2 the needle valve shall open – and
you can see that it bubbles around the needle valve. Now reduce
the pressure down to 0,5 kp/cm2. Check with a few more drops of
fuel that the valve is tight – no more bubbles. If the valve is leak-
ing all the time, clean everything again and change to a new valve
and spring.
If the opening and closing pressure don’t match the values given
in the text, you have to change the spring and lever until it is
correct. Finally, take a last check of the main membrane and
the gasket, there is very little that can go wring with these. If the
carburettor is carefully cleaned and you have checked everything
according to the instructions and the H and L needles are OK
– the carburettor works.
The only problem that can remain now is if the engine is very dif-
ficult to start and don’t react on adjustments of the L-needle. Then
there could be dirt under the expansion washer, which is located
under the main membrane. The fuel that passes the L-needle is
also passing a small chamber on its way to the venturi. In very
rare cases this chamber can be blocked. To solve this problem
you have to drill a 2 mm hole in the middle of the washer (3020)
and pry a thin tool into the hole and bend up the washer. Clean
and check all channels to and from the chamber carefully and seal
it with a new washer. To do this, place a new washer in correct
position and expand it with a gentle blow of a small hammer. That
is all, now your carburettor shall be working. Normally this mem-
brane carburettor will give you very few problems, but sometime
you get a carburettor that doesn’t give good results. Then try to
borrow a carburettor that you know works well. If the difference
between the two is big, you have to buy a new carburettor. It is
very difficult to change a band on into a good one.