SETTINGS AND DETAILS

Jetting: DQ267 – K24 (1.5 clip) 48p – 165-168 main.

Port timings: 197 ex – 128 tr – 180/200 inlet depending on track. Chalky sets the transfers to a level the engine rpm can handle, and then develops the exhaust to gain the necessary blowdown without going crazy high, thus retaining mid-range and rideability. The longer inlet duration can help slow down crankcase transfer delivery by keeping the case open longer, and thus lowering crankcase compression. All alterations to inlet timing were done at piston skirt, not cylinder, which made track-to-track alterations easier. It’s not all about peak power, it’s about balance. Keep a small exhaust duct with oval shape bore on exit, Chalky uses a transitional stub between duct and pipe.

Ignition timing: 15º before 4000rpm – then straight up to 26º after 4000rpm, progressively coming back to 17º at 9000rpm, and finish at 14º in over-rev. Bore and stroke: 67mm bore x 64 stroke in the Group 6.

Head: Buys blank heads 10 at a time and machines his own conical/toroidal heads torqued to 20lb-ft, setting 0.85mm squish and with about 51% squish area depending on MSV dictated by software, giving around 15cc volume in chamber (on avgas) and 6.75:1 CCR. Chalky spends hours on the head, in order to quench the heat sufficiently. He’s never had a seizure on track.

EGT temp: 200º Bits: Air scoop for cooling, welded and reworked inlet with venture effect, machined heads, LPC crankcase compressions to prevent losses via exhaust port, reduce crank turbulence, Mikano AFR. Speed and power: Around 95mph with 34-35bhp.