PRO RACING DESIGN
5
5. ROUTINE ENGINE MAINTENANCE
This section has been provided to allow the owner to carry out sample maintenance tasks to
ensure his engine runs smoothly & reliably. We suggest for the repair & service of a more
serious nature that the owner consults his nearest PRD sales & service outlet.
5.1 Carburetor: The carburetor should be removed and cleaned after each race meeting or test
session. Partial disassembly should be undertaken to the diaphragm area. Dirt or foreign matter
should be removed by washing with a safe cleaning solvent and carefully blow with compressed
air.
5.1.1 Diaphragms and gaskets should be checked for damage and replaced if necessary. [PRD
recommends the use of walbro diaphragm repair kit #350-800 or PRD part #EPY669C where
unleaded fuel is used]
Re-assemble the diaphragms and gaskets in the carburetor body in the reverse order of
disassembly.
5.1.2 High & Low Speed Needles: The carburetor contains 2 adjustable needles. These needles
control the fuel mixture. Carefully remove both of the high & low speed needles, washers &
o-rings. Carefully below the fuel passageways clean with compressed air and refit needles &
other parts in reverse order of disassembly
Needle Adjustment:
Turn In
Leans mixture
Turn
Out:
Richens
mixture
IMPORTANT:
The needle adjustment should be undertaken in 1/8th turn increments to prevent excessive adjustment
that may result in engine malfunction or failure.
Always adjust the LOW speed needle before adjusting the HIGH speed needle.
Symptoms of improper settings:
If your kart exhibits one or more of the symptoms below it may need some carburetor tuning adjustments.
Before attempting any changes make sure that everything else is in good condition and tuned and
operating correctly. Check the condition of the Spark Plug and ensure the ignition timing is correct.
If your kart is TOO RICH, it will:
Accelerate poorly
Misfire
Smoke excessively
Foul the Spark Plug
Have a
“
deep rumbling
”
exhaust note
If your kart is TOO LEAN, it will:
Ping or rattle **
Accelerate erratically
Act like it is running out of fuel
Run extremely hot