Originally Posted by Lille-bror

Depends on how much nitro you are running. A 97T, Novarossi C5 or C6 are great with 30% nitro. Use 77T or similar hot plugs with 25% nitro and 0,7 mm head shims.

If your plug is too cold, you'll have a hard time tuning the engine. With a warmed up engine, it sounds like it is running too rich on the HSN, when you goes to WOT on the starterbox. If you lean it until it runs clean, it will be waaay too lean on the track (perhaps 1/4 turn!!!!).
The idle is rotten. You'll have to lean it too much to have a rather stable idle but after WOT the engine doesn't come down to normal idlespeed for the first 5-10 seconds. After that it will but the engine will often stop.