So many questions, so little time !
Now that SHY is up and running (sort of !) I'd like to know the best way to set up the carb. I'm pretty sure she's running rich, as she hunts on idle and can't settle. Smells a bit rich too. And full choke kills here completley even when cold !
So I'd like to start from scratch with the settings. There used to be a way with SU's on minis that went something like 'screw the jet nut all the way in and then back it off 1&1/2 turns' or something. Is this right ?
What carb do you have? If its a standard HS2 then i think the initial setting is to screw the jet till its flush with the seat (take off the air filter and look down, lifting the piston) then lower it by two full turns.
I had a rough idle for a while, due to an airleak plus timing really far out.
Check the timing first, points gap etc, then adjust the carb mixture. If you have some carb cleaner, spray that around the manifold joints and see if the revs drop, or spray WD40 and watch for smoke in the exhaust to indicate a leak somewhere.
To check the mixture strength have the engine at normal running
temperature and then locate the 'lifting pin' which is underneath the
piston chamber. You take up the free play on this pin which means
that you are pressing it UPWARDS against the piston. Now lift it
slightly,no more than a sixteenth of an inch. The revs at tickover
should increase slightly and then settle back to where they were.
If the revs go up and stay up then the mixture is too RICH and
the mixture nut should be turned UP one flat at a time until the
correct reaction is attained. IF the revs drop or the engine stops
the mixture is too weak and the mixture nut should be turned
DOWN one flat at a time until correct. The starting point for
the mixture nut after a rebuild is 12 flats down from the fully up
position.
ive tried this pin lifting trick, also taking off the air filter and lifting the piston with a piece of wire. i cant get it to work, even screwing the carb 2 whole turns up or down doesnt seem to make much difference. the revs still drop, maybe ive got something wrong. the only sure way i can tell if the mixture is anywhere near right is to check the plugs after a run, currently theyre all a nice tan brown colour, except number 2 which is leaking some oil past the rings i think
yeah i have been promising myself one for a long time now, seems the best way to get it right. i just find its almost impossible to lift the piston only a 16th of an inch
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