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Home >> Cadet Rok >> HS205 Tuning Info
Tillotson HS205A Tuning Information

At the time of introduction to the Kartsport NZ rules an allowance has been given to machine the throttle venturi to size (refer to Kartsport rules for correct specs).

We at Kiwi Karts strongly recommend that you DO NOT machine the throttle venturi any bigger than as supplied.

The Raket 85 engine with a carburettor of this size and without the 15mm restrictor plate, spacer and 1mm barrel spacer but fitted with the tuned exhaust pipe (as per Raket 120) will produce around 9.5 hp. As the restricted setup we have for the Cadet class reduces the output to around 5 hp the last thing the engine will need is a larger carburetor venturi.

With the HS 205A carburetor choke shaft lever plate protrudes past the front face of the casting. There are allowances within the rules to file, grind, or machine the choke lever plate so it is below or flush with the front face so an air box adaptor can be fitted correctly.
The Kiwi Kart Aluminium Air Box Mount is now supplied with a machined clearance to clear the original choke lever plate and allows operation of the choke lever when installed on the engine.
Kiwi Karts recommend the use of these new type of air box mounts.

Our initial testing indicates a setting of 2-3/4 turns for the low speed jet and a little under 1/2 turn for the high speed jet. On track fine adjustment of the high speed jet may be needed each day.

Please Note: It is not possible to tune these carburetors by reving the engine on a kart stand.