Quote Originally Posted by Throbbinhood View Post
Would hate to think what mine is running at. Can smell the fuel out the exhaust at idle haha. When I turn the idle mixture screwn, nothing happens, it never seems to seat - I'm guessing something is broken.

But, it keeps running and I don't have the time to strip it, or the money to pay someone to do it, so I've just gotten used to that lovely petrol smell at idle :P
i wouldn't touch the idle mixture screw at all if I'm you mate.
Even with Gunson Colortune spark plug, it was absolute PITA to tune it or even try turning it.
It's with the wideband AFR gauge now I'm getting a good picture of what's happening inside the combustion chamber.
Both carbies are stuffed and need some serious work on them to get them to run anywhere near AFR, either on idling or cruising.

If the idle mixture screw keeps turning without seating, probably it's was turned too hard in the past and the thread is damaged.
You can take it out completely(don't lose the spring & tiny rubber washer) and examine the thread.

Follow the Gregory's manual temporary carby tuning procedure that I mentioned above to tune it.
Your carby should be in good nick 'cos it's been running on petrol only and the low kms on it.