cheers for that woody, while I remember what carb and jetting do you use on the 340, as my 320 engine is all brand new inside and was rebuilt by some one who knows what the are doing, but as I said before it was great in sections but pinked and knocked between when opened up. Also who makes the larger airbox you mentioned, as mine is still the ty item with inside removed and a ty mono filter in the top. The exhaust is the wes type so Im pretty sure that my problem has got to be carburation and timing ( its also got electronic ignition). Do you know Nick Shield? if so, do you know the set up on his, as it seems to work ok.