Hello With my Aprilia SR 50 I have now in no time driven two Kolber-eaters behind each other what can that be? The first time was a Hebo 68 ccm ,Gianelli auspuff,19 Delorto carburettor with 78 g main nozzle installed, and separate lubrication driven with fully synthetic 2T oil. Running capacity approx. 250 km. Second conversion: Airsal 68 ccm,Technigas auspuff,19 delorto carburettor with 98 g main nozzle,open air filter,(air filter only after the second conversion with built-in) and converted to mixture 1: 50 with fully synthetic 2T oil. Running power about 50 km. Spark plugs was white even after conversion of the larger main nozzle (98 before 78)! Please for good advice! Mfg.