vaccum port, rubber cover?

[Nigel]

New owner looking to sync the carbs using carbmate connected to the vacuum port. Photo attached of the underside of the carburettor. I am right, the vaccum port is covered by a rubber cover? But how do you remove the cover? I've tried but I am worried about breaking it.
Nigel

[Bob_Roller]

Most likely the rubber has hardened with age .
You could try using a pair of pliers and twist it to get it to break free . Try using a heat gun may possibly get  it softened to where it will come off . If that fails cutting it off is the only thing left .
You can get cap from auto parts stores .

[Barry]

The vacuum ports are normal sealed by a small pan head screw and fibre washer.  It might be that the rubber cover was used because the screw had been lost.  It's an odd size thread at M3.5 x 0.6

[Bob_Roller]

North American bikes had rubber caps on the vacuum ports from the factory .

[donbmw]

My 75 R90 has screws in them.

[Bob_Roller]

I had this wrong the North American R65's have a crankcase ventilation system.
The vacuum ports on the carbs were used to open valves in the air box to allow blow by to be routed into the air horns to be burned in the combustion chamber .There were small hoses on the ports and went into the backside of the air box on the '81 and later bikes . There were never rubber caps on the vacuum ports.
I found the screws and fiber gaskets on a Bing parts diagram .

[Nigel]

OK. So I am back to my original question. There are rubber covers (as you can see from the picture). How can I safely removed them?
Nigel

[dogshome]

Hi Nigel, taking a carb off is very easy. If you can't see./ are not sure how to get the cover off safely, get the carb on the bench. It should then become obvious and a small flat blade driver and pliers ought to do the job.

Keith.

[Barry]

If the rubber covers are that tight they may have been on there for a long time. Would they be re-usable ? 

Might be better to obtain some M3.5 x 0.6 screws and not worry about damaging the covers getting them off.

You don't give your location in the world.  Had you been in the UK or any other country that uses the same electrical fittings, then there are dozens of M3.5 screws in every house. The screws used to secure light switches and sockets to the back box are all M3.5 x 0.6. Not the correct head form but they will work in a pinch until the correct pan head screws can be obtained.

[Bob_Roller]

If they are that difficult to remove, use a razor knife and cut them vertically then use pliers and twist them off .
Replacements are available at most auto parts stores.

[dogshome]

I replaced mine with Pozis. Upside down, with a flat head in a spot you can't see, with the screw always falling off =         .... Pozi, magnetic bit =   

[Nigel]

Thanks everyone. Good advice I'm in Providence RI, US.