snaping the throttle on a m20 with a great big flywheel they dont do snap.If it idles ok nice and slow then the idle air circuit is ok.The next step depends on the slide opening the needle height at this stage doesnt matter.So if it doesnt accelerate or starves when you open the throttle at a reasonable rate it could be the main jet size.
Advancing the timing does make them more responsive but not if there starving.

email (option): mhadfield35@yahoo.com.au

My M21 has a carb off an Ariel Huntmaster
The slide isn't quite right
Whilst running in it would spit back [and sometimes stall]
It doesn't do it now it's run in, in fact I'm hard put to pick up the weakness
Perhaps the additional fiction of a new bore made it more susceptable
On Amals the slide cutaway controls just off idle mix. On Mikunis the slide has far less influence

email (option): j@clogmaker.co.uk

Remember these things are older than my grandparents..they need gentle encouragement not "snapping" open of throttles 😂

While these engines may not like having the throttle snapped open, it should not show indications of a weak mixture when doing so and it wasn't a problem with the previous cylinder.
The mixture is so weak off idle that if I snap the throttle open and hold it open the engine chokes and dies.

I've been in conversation with John Parker and I believe that we have found the root of my problem (I'll find out this weekend). This All Parts carb body has had the main air intake for the pilot jet (the hole opposite the pilot screw) blanked off. Also it appears that the jet block has been machined out to the 1 and 1/16 bore and in doing so has removed the small cylindrical up stand where fuel coming from the needle jet enters the air flow. I've unplugged the orifice and I'm fitting another jet block.

email (option): spacemonkeym@gmail.com

Hi Matt

If you have spent time and money on a liner, piston and rings, go the extra mile and buy a new Amal carb.

It will not only transform the starting of the bike, but the performance too. It will also run much cooler.

I persevered with an old tired carb for far too long and it did not do the bike any good (i.e. liners, rings, piston and exhaust guide suffered).

It will save you time and money in the long run.

It is a bit of an expense, but a must have; much like having a good mag.

Regards

Pat

email (option): sacombsashtrees@hotmail.com

G'day Patrick,
I hear you on the new carb but really this one hasn't done a great deal of miles. It appears that the carb body was set up for the later 276 that had the four holes around the base deleted and the pilot intake plugged. I'll be re-fitting the carb tomorrow morning, we'll see what's up then.

email (option): spacemonkeym@gmail.com