Bonneville Carb Question!

So been having some issues with my Bonnie - suddenly started misfiring at random times on one cylinder, appeared to be running rich low down on one cylinder, but once you got up to 70 all ran clean. Cleaned the carbs out and checked them over as I remembered a similar issue on my adventurer and it was the needle seats where the needle "flaps" it had worn the seat egg shaped so too much air. What do you know I have one egg shaped seat. So removed the main jet holder and the needle seat and logged on to Fowlers parts list to order replacements and while the needle seat is shown and has a part number it doesn't show the main jet holder (Emulsion tube) - no one appears to list one for the Bonneville! So I have found some from a Thunderbird, which are the same length etc BUT where the Bonnie ones have 4 x 3 air holes the Tbird has 2 x 3 and 2 x 5 air holes. So the question is two fold. 1) Does anyone know if there is a part ref for the correct Bonneville main jet holders and if not will the Thunderbird ones be okay (I'm guessing that the mixture may need adjusting to allow for the additional air holes. Any advice guys an gals?

 

This is getting stoopid - spoken with Triumph direct and they say there isn't a replaceable part and the main jet screws direct into the carb body. I don't think so!! So you try to contact Kehein carbs to query and they won't respond to enquiries re production carbs, has to be done via the manufacturer only. Going round in ever decreasing circles at the moment. Anyone else had this issue and how did you resolve it? Cheers