Description:

I must/need to sell this car “Minimus” to raise money to continue development of my other Special, “Maximus” , the V8 2 stroke engined sports car. Both cars have now passed the newVIF process and are now recognised as Specials.

S.Special   “Minimus” has the following specification:

Engine

Rotax model 599 engine, 600cc 3 cylinder which has been fully race tuned

Including expansion chambers, 3 Mikuni flat slide carburettors. The completed engine and exhausts were Dyno setup and achieved 158hp at circa 9000 rpm as per attached test result.

Gearbox

The gearbox comes from an Aprilia RSV4 motorcycle engine with just box casing used, leaving behind the original gear drive to clutch with its outer cover which retained engine and clutch oil

Clutch

This was a major item on the project to design and instal a drive from crankshaft to the gearbox, or clutch, drive. The initial chain drive kept breaking since it was up to 9000 rpm!  it was changed to an 8mm toothed 45mm wide belt drive using a CAD machined aluminium ring , 84 teeth on peripheral, welded onto the clutch basket. Of course the plates were working “dry” , not “wet” so that a company, Surflex in Italy, were found who agreed to make, free of charge, a set of dry plates which proven perfect.

Chassis

The chassis, a facsimile of a Jedi, was manufactured using CAD drawings, purchased from.    https://www.t89.co.uk  but was extended by 200mm (8”) to accommodate my 6ft+ grandson. Chassis has not yet been painted fully, to be sure no modifications needed after testing.

Instrumentation/electrics

I have fitted both EGT and AFR sensors with instruments to assist with carburettor jetting.

Fuel

A 5 litre tank aluminium with a pulse electric pump fitted behind bulkhead.

Testing and Commissioning and running at Shelsley

During a 2 year period the small faults have been corrected, unaccesable,in the pits, bolts/nuts. Dissapointment with times at Shelsley led to realising that during Dyno testing a gravity fuel tank had been used, whereas I had fitted a pump , bought for a max of 3psi whereas checking proved it was 5.5psi far too high for the float chamber valves leading to uncurable “running rich”. Converting to a flow and return to tank concept using a small orife in the return line finally gave 0.5 psi pressure to the carbs  solving problem but time/money prevents further runs at Shelsley this year.

Exhaust noise level

Always a potential problem with 2 strokes the expansion chambers were built with the stinger (final outlet) extended into the belly of the pipes where noise level is 50% of final outlet allowing me to pass noise tests at Shelsley with 108db. 3 silencers bringing noise level to 89db are included in the sale , engine runs much better without them.

The experience has shown the difficulty/frustrations of building running specials but when they run and attract the crowds of spectators/competitors looking and with questions it does make up for the hours and money spent doing the construction.

The car has a MSUK logbook/passport

Keyword Search Terms:

Shelsley Special, Hill Climb