hi.

i have a pipe sticking out of the first cylinder inlet below the carb. it has a screw in it at the moment and some oil residue around it.

what is this pipe?

There are vacuum points on all 4 clyinders. Likely to be one of those.

No1 cylinder is back and left? That one?

its the front left. should this be blocked?

yes, should be blocked. It is used for carb balancing, you attach the vacuum gauge to the little pipe - there should be the same on all cylinders and the one from cyl 3 goes to the fuel tank and opens the fuel tap when the motor is running

If the pipe is there for the vacuum tap , it could of once been a chain oiler pipe