Monoblock carburettor main needle.

[Barnsey]

Hi All,

   I have just rebuild my monoblock 375 carb.  Now last of all to fit the new main needle, but which slot should I mount it on?  The needle has a choice of 5 slots at the top.  I think Hugh Ferrier used the middle one but mine was on the top slot, so I guess this is throttled right back. 

   BR,  Ian

[Barnsey]

I took a guess and went with slot no2.  It should be easy enough to change if I need to.

[Kernowpete2]

If it was me I'd put it back in the original position and go and do a few plug chops. You may get a starting point if you ask Amal or from the owners manual but it all depends on levels of wear, inlet and exhaust pressures (type of air filter, silencer etc) so you need to be able to tune it to match the bike. It's not tricky. Do you have the Ratio book? There is plenty of info in there on carb tuning.

[Barnsey]

Fair point.  I was making some allowance for having replaced the jets with new.  .  Maybe the needle was moved out due to wear and tear and now I can put it back again.  Yes I have Rupert's book and I was reading though it. Although it mentioned the notches it didn't say which to go with.  Maybe I need to read through that section thoroughly!  Roll on next weekend!