A Bit Up The Creek With Delly 28mm

[bootros]

I'm an advocate of testing needle/atomiser combinations by running (and riding if you want) with the main jet removed. If the needle/atomiser are in the ballpark then the engine should bog down at 3/4 throttle. Continuing above 3/4 or bogging down way before shows that the needle/atomiser are incorrect - above 3/4 is weak, below too rich. Plenty think this a bad idea due to the overlap of the main jet but it worked for me. My st4 200 with 28 delly, av264, x7 on second clip bogged down completely at almost exactly 3/4 throttle. This gave me the confidence to concentrate on the main jet to fine tune the settings. If you do try this make sure the throttle positions are marked accurately, I used 7, 14 and 21mm widths of card shoved in the carb mouth to act as a feeler gauge and marked the positions on the twist grip (did this inaccurately the first time and made a mess of the tests).

[J1MS]

^^^^^ Main jet removed test; is the good old Skool way of doing it, as Bootros says.^^^^^ has worked for me...

[rog60]

I've seen this as well, but I'm inclined to concentrate at the moment at the lower end as this is where the 'splutter' seems to be (just as throttle is being opened). I will try the (no main jet afterwards)

Thanks for continuing advice.............