Cobra cm-50 2006 Owner's Manual
2006 CM-50
Owners Manual
Allegan Motorsports - 800-475-5660
June 2006
For parts orders contact your local dealer
To
locate your closest Cobra dealer
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www
.cobramotorcycle.com
or call
(330)
you need technical assistance
If
contact
your local dealer or call
549-9600
Cobra Technical Support Hotline at
(330)
549-9603
Cobra Motorcycle MFG., Inc.
11511 Springfield Road
North Lima, Ohio 44452
1
MCCM2006.2
DISCLAIMER OF WARRANTY
This motorcycle is sold “as is” with all faults, obvious or not. There are no warranties
expressed or implied, including any warranty of merchantability and warranty of fitness
for any particular purpose.
“WARNING”
THE COBRA CM50 IS A COMPETITION MODEL ONLY AND IS NOT
MANUFACTURED FOR, NOR SHOULD IT BE USED ON PUBLIC STREETS, ROADS
OR HIGHWAYS.
THE USE OF THIS BIKE SHOULD BE LIMITED TO PARTICIPATION IN
SANCTIONED COMPETITION EVENTS UPON A CLOSED COURSE BY A
SUFFICIENTLY SKILLED RIDER AND SHOULD NOT BE USED FOR GENERAL
OFF-ROAD RECREATIONAL RIDING.
IMPROPER USE OF THIS MOTORCYCLE CAN CAUSE INJURY OR DEATH.
THIS BIKE IS INTENDED FOR EXPERIENCED RACERS ONLY AND NOT FOR
BEGINNERS.
IT IS YOUR RESPONSIBILITY AS THE OWNER OF THIS COBRA MOTORCYCLE
OR AS THE PARENT, OR LEGAL GUARDIAN OF THE OPERATOR, TO KEEP THIS
COBRA MOTORCYCLE IN PROPER OPERATING CONDITION.
THIS BIKE WAS DESIGNED FOR RIDERS THAT WEIGH LESS THAN 80 LBS WITH
FULL RIDING GEAR AND SHOULD NOT BE OPERATED BY RIDERS THAT WEIGH
MORE THAN THAT.
BE SURE THAT THE RIDER ALWAYS WEARS ADEQUATE SAFETY GEAR
EVERYTIME HE OR SHE RIDES THEIR COBRA MOTORCYCLE.
IMPORTANT SAFETY NOTICE
Failure to follow WARNING instructions could result in severe injury or death to
the machine operator, a bystander, or a person inspecting or repairing the
machine.
CAUTI ON:
A CAUTION indicates special precautions that must be taken to avoid damage to
the machine.
NOTE:
A NOTE provides key information to make procedures easier or clearer.
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Table Of Contents
General Information .........................................................................................................5
Specifications - General..............................................................................................5
Specifications - Torque Values ..................................................................................6
Optional Components..................................................................................................7
Break-In Procedure......................................................................................................8
Starting Procedure .......................................................................................................9
General Tips................................................................................................................10
Maintenance....................................................................................................................11
Schedule & Tips .........................................................................................................11
Replacing Transmission / Clutch Lubricant............................................................12
Chain adjustment .......................................................................................................13
Front brake adjustment .............................................................................................14
Rear brake adjustment ..............................................................................................15
Air Filter Cleaning .......................................................................................................15
Fork Oil Replacement................................................................................................16
Servi
ce .............................................................................................................................40
Engine Service............................................................................................................40
Engine Removal .....................................................................................................41
Complete Engine Disassembly Procedure.........................................................42
Top End Disassembly Procedure ........................................................................42
Splitting the Cases .................................................................................................43
Engine assembly ....................................................................................................44
Clutch ...........................................................................................................................46
Ignition..........................................................................................................................51
Cooling System...........................................................................................................53
Fuel & Air System.......................................................................................................57
Exhaust ........................................................................................................................60
Wheels & Tires ...........................................................................................................61
3
ng ..............................................................................................................................61
Tuni
Suspension..................................................................................................................61
Rear shock ..............................................................................................................63
Front Forks ..............................................................................................................63
Gearing ........................................................................................................................64
Carburetion..................................................................................................................66
Troubleshooting ..............................................................................................................68
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General Information
Specifications - General
Items CM 50
Dimensions
Wheelbase 35.75” (908mm)
Wheel size 10” (254mm)
Seat height 23.9” (607 mm)
Engine
Type 2-stroke, single cylin der, reed valve
Cooling system Liquid-cooled
Coolant Liquid Performance Mini Coolant or Antifreeze
Displacement 49.8 cc
Bore and stroke 39 mm x 41.7 mm, “V” head
Ignition system Electronic, analogic advance
Spark plug Champion 8339-1, 8332-1 hotter, 8904-1 colder
Gap 0.023” – 0.025” (0.58 – 0.64 mm)
Ignition timing 0.045” (1.14 mm) Before To Dead Center (BTDC)
Fuel type High octane pump gasoline
Oil type Cobra Venom 2-cycle Race Oil
Fuel / oil mix ratios Between 32:1 and 40:1 (after engine Break-In)
Carburetion 14 mm Dell’Orto
RACE FUELS ARE NOT RECOMMENDED
Main Jet 92
Slow (Pilot) jet 55
Float Height 16mm + 0.5mm (0.63” + 0.020”)
Transmission
Speed / Clutch Single / Cobra 3 shoe
Final drive ratio 13/38T or 14/38 T
Chain 420
Transmission / clutch oil type Cobra Venom 3 Shoe Clutch Milk
Quantity 235 ml (8.0oz)
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Chassis
Front tire 2.50 – 10
Pressure 15 psi minimum
Rear tire 2.75 – 10
Pressure 15 psi min. (20 psi for hard pack or rocky conditions)
Front fork Marzocchi 32mm
Fork oil type SAE 20 weight
Fork oil amount 200 ml (6.8 oz) oil change, 220 ml (7.4 oz) rebuild
Collapsed fork oil height 70 mm (2.75”) spring in, no spacer
Specifications - Torque Values
Torque Value
Fastener
Cylinder head nuts
Crankcase bolts
Spark plug (SP) (SP) (SP) M14 x 1.25
Stator bolts 2.1 25 2.8 M5 X 0.8
Stator cover bolts 1.7 20 2.3 M4 X 0.75
Clutch cover bol ts 5.8 70 7.9 M6 X 1.0
Clutch nut (max.) 40 480 54 10 x 1.25*
Clutch bolts 12 144 16 M6 x 1.0
CFD nut 55 664 75 ½” x 20 LHT
Engine mount bolts 22 265 30 M8 X 1.25
Swingarm Pivot 21 250 28 M14 X 2.0
Intake manifold bolts 4.6 55 6.2 M6 X 1.0
ft-lb in-lb Nm
8.8 105 12
8.8 105 12
Size &
Remarks
M6 X 1.0
M6 x 1.0
Ignition rotor nut 40 480 54 M10 x 1.25*
Rear Sprocket Bolts 18 216 24 M7 X 1.0
Rear shock mounts 40 480 54 M10 x 1.5
Axle nuts 25 300 34 M12 X 1.25
* Apply high strength thread locking agent when installing
6
(SP) To apply the proper torque to the spark plug when inserting, one must first
screw the spark plug in until the metal gasket ring causes resistance and then
turn another 1/8 to ¼ turn.
Optional Components
Call your dealer, or the factory, for details
• Carburetor jets
• Pre-filter for the airbox
• Sprockets
o Front
o Rear
• Suspension Springs
Weight of Rider (lb) Fork Spring Shock Spring
Less than 38 (light) KCMZ0012A
(12 lb/in, 2.10 N/mm))
38 – 45 (std) KCMZ0012
(14 lb/in, 2.45 N/mm))
46 to 55 (stiff) KCMZ0012B
(16 lb/in, 2.80 N/mm)
• Suspension valving
Damping Rate Fork Valving
Compression
(right)
Soft (fast) KCMZ0033A KCMZ0032A SCMUOH07
Standard KCMZ0033 KCMZ0032 SCMUOH08
Hard (slow) KCMZ0033B KCMZ0032B SCMUOH09
• Tires
• Tubes or ‘Tire Balls’
Fork Valving
Rebound
(left)
SCMUOH04
(275 lb/in) red
SCMUOH05
(285 lb/in) yellow
SCMU0H06
(295 lb/in) white
Shock Valving
(kit)
7
Break-In Procedure
Your Cobra CM50 is a close-tolerance high performance machine and break-in
time is very important for maximum life and performance. The CM50 can be
ridden hard after the first ½ hour break-in time but it is recommended that no
adjustments are made to the carburetion or suspension until the full 8 hours of
bike break-in has elapsed. Also, after the engine, transmission, and drive train
have been broken-in for the full 8 hours, the bike will be faster!
Use a fuel / oil mixture of 32:1 for the full 8 hour break-in period. Be sure to use
high octane pump gas with Cobra’s specially formulated Cobra Venom 2-cycle
Race Oil
CAUTION:
Failure to use proper fuel, oil, or fuel/oil mixture may result in premature engine
wear or damage to the machine.
Adhering to the following break-in schedule will result in long lasting high
performance machine.
• Start bike on stand
• First 5 minute period, operate the bike on the stand with a combination of idle
and high RPM operation. (avoid prolonged high RPM but spin the rear
wheel good at least once or twice per minute)
• Allow bike to cool
• Ride for 15 minutes maximum (avoid prolonged high RPM operation and
avoid abusing the clutch with throttle blipping.
• Cool and inspect bike for loose fasteners.
• Next ½ hour of operation, avoid prolonged operation at Wide Open Throttle.
• After 1 hour of operation
o Check for loose bolts and nuts on the bike and retighten as
necessary (proper toque values are listed under Specifications).
o Clean the carburetor bowl.
o Change the transmission / clutch lubricant.
• After 8 hours of operation
o Change the fork oil.
o Have a Certified Cobra Mechanic change the shock oil.
• Your bike is now ready for the highest level of competition!
NOTE:
During break-in the bike will likely lose some engine coolant through the radiator
overflow hose. Losing up to 4 oz (120 ml, ½ cup) is normal. Proper coolant level
will cover the top of the radiator cores. Removing the radiator cap and looking
inside is the only way to check the coolant level.
Allegan Motorsports - 800-475-5660
8
June 2006
Never open the radiator cap of a machine that has a hot or warm engine or one
that has recently been ridden. Burning and scalding could occur.
CAUTION:
It is important that the radiator cap is installed correctly and completely otherwise
engine damage could occur.
Starting Procedure
Before starting the machine inspect the following:
• Make sure vehicle is properly maintained (see Schedule & Tips in the
Maintenance section)
• Check the throttle for smooth operation and sound closing.
• Insure that the fuel tank contains an adequate volume of fuel / oil mixture to
complete the distance required. (High octane pump gas with Cobra’s
specially formulated Cobra Venom 2-cycle Race Oil)
• Turn the fuel on by rotating the fuel petcock knob to the vertically downward
position (reserve position is horizontally forward)
CAUTION:
For best results from your Cobra Motorcycle use only the recommended fuels.
Testing has shown that most ‘race’ fuels actually degrade performance.
When your pre-ride inspection is complete the bike may be started. For a cold
engine follow this procedure.
1. Place the motorcycle on a stand of sufficient strength that positions the
motorcycle in a level upright position with the rear wheel off the ground.
2. Pull up the choke knob and turn it to lock it.
3. Kick start the engine.
4. Rev the engine in short spurts, turning the throttle no more than 1/4 open
until the engine will run without the choke.
5. Verify a functional engine shut-off switch by shutting off the engine.
6. Restart the engine and proceed with riding when the engine is sufficiently
warm (i.e. the side of the cylinder is warm to touch).
CAUTION:
Never rev an engine full throttle when it's cold or slightly warmed up. Cobra
recommends that you tell your child to take it easy the first couple of minutes in
practice until the engine comes up to full operating temperature. Make sure your
engine is properly warmed up before racing.
This is a high performance race motorcycle. Too much application of throttle will
likely land your little racer on his or her arse. Fenders can be replaced but
bruised egos and other body parts take longer.
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General Tips
1. Always wear a helmet and other protective riding gear.
2. Cobra recommends that you tell your child to take it easy the first couple of
minutes in practice until the engine comes up to full operating temperature.
3. Make sure your riders’ foot is not resting on the foot brake while they are
riding.
4. Evaluate the bikes jetting only after it has been warmed up to race
temperatures.
5. A properly maintained machine is safer, faster, and more fun to ride.
6. Cobra offers a carburetor inlet cover RCMU0109 to keep water and dirt
from getting into the carburetor when the bike is being washed.
7. New chains will stretch on first use. Never install a new chain prior to a
race. Always ‘break’ them in during practice.
8. Your Cobra Motorcycle has a 10 digit VIN (Vehicle Identification Number).
The first two digits indicate the model and the seventh indicates the model
year (MY).
a. Example, CMxxxx6xxx is a 2006 Model Year CM50.
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Maintenance
Schedule & Tips
It is important that you adhere to this maintenance schedule so as to promote the
longevity of your Cobra Motorcycle.
• Between each ride
o Check the air filter (clean and re-oil as necessary).
o Insure the smooth operation of the throttle cable (throttle soundly
‘clacks’ shut).
o Check for frayed strands of the throttle cable inside the throttle housing
and replace if necessary.
o Check for adequate tire pressures and adjust if necessary.
o Check all nuts and bolts for proper torque and re-torque if necessary.
o Spray all moving parts with WD40 or other light oil.
o Check drive chain for
§ Proper tension and adjust if necessary.
§ Adequate lubrication and lubricate if necessary.
o Insure that the ignition stator and rotor are clean and dry.
o Check the frame for cracks in the metal or cracks in the paint that
might indicate that the metal has been stressed beyond it’s safe limits.
Replace or get properly rewelded as necessary.
• Every 2 hours of operation
o Replace the transmission oil.
• Every 10 hours of operation
o Replace the fork oil.
o Hav e the shock oil replaced by a Certified Cobra Mechanic.
CAUTION:
1. Because of the amount of heat generated by the clutch and engine during
extended periods of riding, it is advisable to remove the ignition cover
afterward to allow the ignition to cool off. The heat transfers through the
cases and can damage the stator as it cools off because of lack of airflow
around the stator.
2. If you ever need to weld anything on the bike, disconnect the spark plug
cap, unplug the ignition, disconnect the kill switch, scrape the paint bare
near the area to be welded and put the ground clamp as close to the area
to be welded as possible.
3. Inspect CFD every couple months and replace paper when thickness is less
than 0.6mm.
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Be sure the fuel tank and carburetor have been removed and safely located
away from the welding process.
4. The frame is 4130 Chrome Moly and it is important to weld it with the proper
rod and heat settings set as light as possible. Cobra recommends replacing
the frame with a new one if the old one becomes damaged.
5. If your kick-starter lever does not return properly, first try loosening the six
kick/clutch cover screws ½ turn. Hold the kick lever ½ way down while
retightening the six screws starting for the center and working out.
Replacing Transmission / Clutch Lubricant
Tools needed:
• 225 ml (7.6 oz) Cobra Venom 3 Shoe Clutch Milk.
• 13 mm combination wrench
Procedure:
1. Begin this procedure with a bike that has been ridden more than 5 minutes
but less than 10 minutes. It is desired to have the engine warm enough so
that the oil is ‘runny’ but not so hot that there is risk of being burned by the
engine or the oil.
Hot oil and hot components on the
motorcycle may cause burns.
2. Lean the bike against something or set
on stand with oil drain hole.
3. Using a 13 mm wrench, remove the oil
drain bolt located on the right side of
the engine, on the clutch cover, near
the brake lever (Item 2, figure 1).
NOTE: You may need to adjust the brake pedal (up or down) to gain access to
the drain bolt.
4. After it has drained, reinstall the bolt being sure that the copper gasket is in
place. Torque to 15 Nm (11 ft-lb).
5. Reapply oil from oil fill plug 235 cc Cobra Venom 3 Shoe Clutch Milk thru the
fill plug.
Allegan Motorsports - 800-475-5660
Figure 1
12
June 2006
NOTE:
Lean bike over onto it’s left hand side so that the clutch cover is up unless you
have a squeeze bottle.
6. Reapply the oil fill bolt, hand tight, being sure the fiber gasket is in place.
CAUTION:
Cobra has spent considerable time and money developing the proper lubrication
to handle the harsh environment of the automatic clutch and transmission of this
motorcycle. Cobra’s specially developed Cobra Venom 3 Shoe Clutch Milk was
formulated to provide superior lubrication and cooling capability over
extended periods of time and is the recommended lubricant for your Cobra
motorcycle.
Chain adjustment
Tools required for chain adjustment
• 19 mm wrench or socket
• 13 mm wrench or socket
1. Make sure that the rear wheel is
aligned properly.
2. For proper adjustment, the chain
should have 35 mm (1 3/8”) free
movement just behind the chain
block with no load on the bike
(figure 2)
CAUTION:
Sit on the bike and verify that the chain has a minimum of 12mm (1/2”) free
movement when the chain is at it’s tightest point.
Allegan Motorsports - 800-475-5660
Figure 2
13
June 2006
3. If the chain requires adjusting, loosen the
axle with a 19 mm wrench and tighten the
chain by rotating the adjustor bolts
clockwise (CW) or loosen the chain by
rotating the adjustor bolts (CCW).
4. Retighten the axel bolt to 25 ft-lb (34 Nm).
5. Retighten the adjustor bolt
Figure 3
CAUTION:
Always check rear brake adjustment and free-play after adjusting the chain.
Front brake adjustment
Tools recommended for front brake maintenance:
• 10mm open end wrench
Figure 3, from the brake lever Figure 4, from the brake hub
From the brake lever:
1. Slide the cover out of the way
2. Loosen the locking nut on the brake lever.
3. Adjust the bolt to desirable position.
4. Tighten the locking nut.
5. Slide the protective cover back over the lever pivot and adjustor
From the brake hub:
1. Loosen the 10mm nut on the hub.
2. Adjust the brake cable to desirable position
3. Tighten the 10mm nut.
CAUTION:
If y ou tighten the front brake up too much, the brakes may hang up causing the
brake pads to wear incorrectly and prematurely.
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