mattylad Posted January 21, 2017 Report Share Posted January 21, 2017 (edited) I have just built a 305 and need to check the jetting used for modern fuels as this bike has not run since the days of leaded. Can anyone advise what they are using today for especially the needle and needle jet. Mine is currently fitted with the following: slide 3.5 needle X7 or possibly X75 as the 5 is very faint atomiser 262FD main jet 125 idle jet 33 idle emulsion tube BF 1 choke jet 70 float 9794.5 2.8g Edited January 22, 2017 by mattylad Added info Quote Link to comment Share on other sites More sharing options...
fantic240motor Posted January 22, 2017 Report Share Posted January 22, 2017 I've personally haven't re-jetted any of my old bikes but I have found it necessary to get the octane up to avoid the unwanted knocking (especially on the over run) when hot. Air cooled bikes from that era seem to suffer from it. I use Fuelx Formula 6 octane booster with super unleaded and have found all those issues stop. Another point on all my Fantics is the pattern head gaskets I have come across are rather thin so I used two of them to bring keep the compression to the original specs. Quote Link to comment Share on other sites More sharing options...
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