73 Trophy

1 3/4 turns is quite a lot but if your plug is still sooty I would try a little more at 1/4 turn per go.
Give it a good all thrashing between adjustments as well to allow any changes to properly show up.
If the carb is a bit worn you may need to look at new jets to get to where you want.

 

Hi Neil,
Yes, I should have been a bit more careful in my choice of words when I said 'thrashing' I meant more of a good few miles at a reasonable pace so the changes would become noticeable.
I personally think your carb may be ready for a bit of TLC

 

Hi Neil, I would price up the jets separately and if only a few quid would probably change the jets first.
Check for general wear also on the slide and needle etc.
It depends how bad the running condition is wether or not it's worth spending £100 on a new carb.
£100 is not a bad price for a full new carb but if you can cure it for £10 better still.

 

You could try setting the tickover by getting the engine fully warmed up then, with the engine ticking over, raise the tickover speed to its maximum using just the mixture screw. Then reduce the speed using the cable adjuster on top of the carb to get it back to normal (I'm assuming Amal concentric and that my memory hasn't faded totally from when I were a lad!). At this point the base setting should be about right. (A couple of throttle blips would not go amiss when idle speed seems about right.)
I'm with Mick as far as the rest of goes. Throttle slides can get scored if there is no air filter, as can the carb body - then it is new carb time!
I don't know what the basic carb settings are i.e. jet sizes, throttle slide cutaway, needle position and float height etc., but I guess that would be what to aim for.
Just be grateful that you only have one carb to deal with. My '69 Bonneville could be a pain in the bum to set up, but it flew when sorted (as my mate Trevor found when I blew his CB750 away .... several times - fnaarr, fnaarr!). Happy days!

 

No need for apologies on here Neil, we are all learning as well as passing knowledge on.
What you are saying about the bikes performance could be related to several things.
Ignition timing
Points, condenser, coil,
Plugs, plug leads
Valve seating & clearances
Carburation
All these are relatively low cost or no cost adjustments and if you work through them one at a time you should find which gives you the improvements for a better running engine

 

Have a read of this mate;
https://www.princeton.edu/ssp/65-cub-data/library/amalbritbike.pdf

 

Well done , Rocker.
Don't know where you found that but it will help old fools like me to remember when we was yoofs, and what we were trying to do, even if we didn't know exactly how and why it all worked. Strange that we mostly got it right even if it was usually by trial and error.
Good work!