First job I tried this morning was to see if the spark plug on the faulty cylinder (#4) was sparking. It wasn't sparking so I thought faulty plug. Changed the plug for another one and I got a spark. I also snipped a bit of the HT to make a better connection. Refitted the plug etc. Pressed starter button and still on 3 cylinders. #1#2#3 downpipes were very hot, but #4 wasn't hot at all. I swapped the HT leads over to 1 & 4 and still number 4 was still cooler than the rest.
I'm now starting to think it's a fuel problem. (Carb's) took the carb's off and gave #4 a good clean out. Fitted the carb's back on and started her up, but this time there was a bit more heat in the downpipe. I took the carb's off again and stripped them all down. As I took the diaphragm tops off I came across what looks like coal dust. See photo...

As you can see #1 is pretty clean and it gets worse as it get's to #4. What I want to know is where does this all come from???
As I continued with the carb strip. I took the diaphragms out and noticed #3 diaphragm had a big rip in it.

Luckily I have a spare set of carb's to take bits from. Unfortunaletly I've come to a halt now because I've borrowed a diaphragm from the spare carb's but it seems it's shrunk a little bit. I've read the post from Bonly1 about using Autoglym Vinyl and rubber cleaner and a tin of Williams specialist tea. I'll be going into town tomorrow morning for some Autoglym. I haven't got a tin of tea, so I'll have to find something else to use.
One question I have is could that tear in the diaphragm on #3 carb cause the problem on #4 cylinder?
To be continued.....
