Gearing can vary greatly depending on circuit layout, grip level, weight and many other factors. Below is a loose guideline to assist in finding the optimal gearing.
To work out your appropriate gearing you need to be doing around 13,000 RPM + or - 400 RPM, depending on the circuit layout.
To work out your appropriate gearing you need to be doing around 14,500 RPM + or - 400 RPM, depending on the circuit layout.
16:1, this is on the safe side as we do not know the quality of oil some customers use or the age of the fuel.
It is essential preventative maintenance to oil the air filter with a good quality filter oil, a normal procedure for any reed valve engine. As is the nature of a reed valve engine the carburettor is mounted on the front of the crankcase leading through to the Crankshaft. A poorly maintained air filter will increase the chance of dirt entering the engine shortening the life of bottom end components.
A brand new or freshly rebuilt engine has to be run in before going flat out to achieve peak performance and engine life.
It is suggested to run-in for one 30 minute session consisting of 3 x 10 minute segments.
Now that you have run-in your KA100 Reedjet engine you can set the high jet back to the normal operating setting.
Each time you hit the circuit it’s recommend to complete at least 1 warm up lap, as is a normal procedure for any high performance kart engine, before you go flat out down the straight for the fist time.
By not warming the engine up correctly, you run the risk of cold seizing the first time down the straight as the piston expands at a greater rate than the cylinder wall causing the piston to bore clearance to become tighter than normal.
To prolong the life of the exhaust springs it is good practice to wrap tie wire or a long pedal spring (100mm or so long) around the two exhaust springs to stop them from vibrating.
Cold Weather: NGK B8EGV
Hot Weather: NGK B9EGV - B10EGV
Your engine comes standard with an NGK 10 heat range plug, this is a conservative plug and may run too cold in some climates to burn the fuel as efficiently as possible, potentially leading to a fouled plug. If this occurs moving to a hotter burning plug (B8-B9) will prevent any issue. Testing has found an NGK B9EGV plug to be the best “all rounder” and will work in most climates.
Before putting your kart on the track for the first session you must prime the carburettor with fuel, this will ensure your engine will start first time while avoiding frustration and unnecessary wear on the starter motor.
Screw the spark plug out of the engine and place it on the cylinder head with the plug boot attached, now remove the airbox. Place your hand or hold a rag over the front of the carburettor and press the starter button. This will choke the engine, drawing fuel out of the tank and into the carburettor. Hold your hand against the carby until you feel or see fuel running out the front of the carby. The engine is now primed and you can replace the airbox and spark plug.
When starting the engine to head out for a session it is best to have the throttle pedal cracked slightly open (with foot on the brake), simply press the start button and drive straight out of the grid. It’s not a good idea to sit idling for a long period of time as this can foul the plug.
After leaving the grid, give your KA100 engine a short burst of full throttle, this will help clear any accumulated fuel in the engine.
During the formation laps prior to getting a start, it is advisable to drive the roll up laps at a constant speed with your throttle at a cracked open position while applying slight pressure to the brake. This will put the engine under load and burn any excess fuel, reducing the chance of fouling a plug and ensuring the engine will accelerate crisply off the line giving you an excellent start!
As your KA100 engine runs so efficiently in cylinder head temperature, on the roll down laps there is a possibility that you will accumulate un-burnt fuel in the combustion chamber. As a result it may be possible to foul a spark plug when starting the engine prior to your next session. To help prevent this, simply hold your throttle pedal on the cracked open position (around 4000rpm) while applying slight brake pedal pressure (this is called 'riding the brake') before coming to a stop, this will put the engine under load and burn any excess fuel. Alternatively you can depress the kill switch on the way into the in-grid and just roll into your stop position.