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Written by Vic R   


Fireball 125CC

Premium Unleaded
Castor/Synthetic Kart Oil
Fuel/Oil ration
Mixture adjustment - Low
1 1/2 - 1 3/4    (1 3/4 during run in)
Mixture adjustment – High
1¼  – A low setting may cause engine failure
Tyre pressures (cold – in shade)
8 PSI - MG Yellows
12PSI - MG Reds
Front wheel spacers
20mm each side
Front wheel nut tension
Should be able to turn spacers with fingers
+2 mm
Wheel Alignment
+1 mm out
Rear Wheels
15mm Slack, Lube chain after each session
Water Temperature
Max 10,000 RPM until engine water temperature is greater than 45C.  Ideal temp 55C. Max Temp 75C
Run in procedure
 RPM Range
1st Session of 10 minutes
5,000 – 8,000 RPM
2nd Session of 10 minutes
5,000 -  10,000 RPM
3rd Session of 10 minutes
6,000 -  12,000 RPM
Maximum recommened RPM after run-in.
15,000 for max engine life

Continually change the revs over the range specified in the table above.  This should be done under full load.  For example – a Fireball should continuoully be accelerated from 5,000 to 8,000 revs during the first session.

Allow the engine to rest for 5 – 10 minutes between each session.

Check all nut and bolt tension at the end of run-in

During the run-in period, excess fuel may accumulate in the air intake airbox.  Smoke will also be seen from the exhaust.  This is normal when engines are run at low revs.  The spark plug may foul due to excess oil in the engine.  Change plug if engine does not start.