I like this answer...
Quote:ok I have a tuned bsa c25 engine and its a fit engine but it seems to not get enough fuel? it runs well but its white in center of spark plug and it seems a tad short on power? the air/fuel is in all the way=rich and I've tried the choke on full and half. I've stripped it down to c if out is blocked but it isn't. help?
Quote:This is one of the worst carbs to tune. The air/fuel screw should be set to 1 1/2 turns out. If it's all the way in and still runs, you need to replace the screw (the tip is probably bent). Next, start checking for air leaks. AmalMK1s provide enough fuel for the bike, your leg and the ground. If it's running lean, it's from to much air
Your PO was a masochist.... did he also convert the electrics to Lucas?
There are so many ways this could go wrong, take one and chase it down.
I'd find somebody with a diagnostic scope and hook it up, it'll tell you a lot.
But I have to go with JOG's answer... jetting is most likely the issue.
and we need pictures, this is the most wild a$$ed mod yet.