Hi, I had perfect running twin su or 'Hitachi' carbs that I removed and sat on my bench for a month.
Put them back on and they won't run at all.
They may have been turned upside down but other than that I can't think of any reason why they won't run.
They won't even fire at all.
Any ideas ?
Cheers

Have you cranked it over for a fair while to fill the float chambers ?

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1970 ex Group A Rally P510
1971 P510
1972 180B SSS
1965 SP310 Fairlady
1966 SP311 Fairlady

30 seconds or so. Is that long enough?

30 seconds may not be enough. Standard pumps take a while to get the fuel to the carbs

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Circuit Race 1600 in the build

Thanks, better put them back on and give them another try.

Try spraying a bit of "Start you Bastard" or similar in the carbs just before starting.
I find it helps to draw the fuel through from the tank to fill the float bowls if you have a mechanical fuel pump.

Mick

What this man said. I've never timed mine, but it often gets left to sit for many months between race meets and takes a lot of cranking to fill the fuel filter and both float chambers using the stock mechanical pump the next time I use it.

You could tip an inch or two of fuel into each float chamber before you try to start it.

All I can think of that would be messed up by tipping them upside down is that the oil in the top of the carbs may have escaped. This shouldn't stop it from firing up though.

_________________
1970 ex Group A Rally P510
1971 P510
1972 180B SSS
1965 SP310 Fairlady
1966 SP311 Fairlady