excessive oil-vapour residue

Hi all, as my cold start problems are still on-going i've just been told this comment below about my old carb 'the top section of the carburettor is coated in excessive oil-vapour residue', can anyone explain what this means..i've also been told my compression could be the cause of the cold start problems, due to the fuel & electrical systsems getting the all clear, my compression is about 140 i'm told…anyone shed any light on this for me please

chally34uk said

Hi all, as my cold start problems are still on-going i've just been told this comment below about my old carb 'the top section of the carburettor is coated in excessive oil-vapour residue', can anyone explain what this means..i've also been told my compression could be the cause of the cold start problems, due to the fuel & electrical systsems getting the all clear, my compression is about 140 i'm told…anyone shed any light on this for me please

140 compression is (I presume) 140 psi, which equals 10 bar which is about right for a 10:1 compression ratio, which also sounds correct.

Excessive oil in the carb is due to oil getting into the breather system (worn engine) and being re-circulated into the intake air (required, to satisfy legislation forbidding the venting of crankcase fumes straight to air).

What this means is that you've some oil fumes being recirculated into the breather system because the engine is somewaht worn (How many miles are on it?), but that it's not too badly worn, because your compression ratio sounds reasonable.

Hard to say how all this should affect your cold starting, but it might be one of two things: the carb is more worn than everyone thinks, and together with being a bit gunged up by oil fumes, is have trouble doing cold-starts.

Try cleaning it with carb cleaner (aerosol) and an old toothbrush. Ask your mechanic to clean the jets (or show you where they are), and also to tell you which screws/fittings that you SHOULDN'T touch  :wink:

114k miles & brand new weber, with manual choke!!!

Hey chap. what was your tank like? any stuff i there? the PSI is within limits m8 , was that your lowest PSi on all 4 cyls. Ive run out of idea`s.