9 replies to this topic

[Maxmini]

I am just rebuilding my twin 1"1/4 carbs for my 1380cc and I would like to know what carb needles do I need. I brought the carbs second hand and he was running them on his 998cc . The needles are AAC at the mo are these ok to start with.

[Sprocket]

1 1/4"s a bit tame for a 1380

Have you tried WinSU

[fikus01]

excelent throttle resonse tho i have to say!! i cant see it hurting performance!! needle choice is a hard question tho!! i'll hav e a look in the big yellow book

[Maxmini]

Do you think I would be better selling the carbs and getting some 1"1'2 twins.

[fikus01]

the vizzard needle selection chart is slightly complicated!

doesnt list 1380's!! but a 1275 with semi race cam and modified head is a red carb spring and AF needle!!

the twin 1 1/2" carbs seem to be for the big performance race motors and the high reving ones (1071 and 970)

1275 +modified head+extractor exhaust+race cam = blue or red spring and bg needle!!

hope that helps!!

[Maxmini]

I will have a look at what I have i.e springs and maybe get some red springs and AF needle to start of with.
I have a stage two head with a 276 cam and stage two maniflow manifold so I guest this is a midrange sort of engine.

[The Matt]

Well, with the twin 1.25" carbs, it should be nice and torquey, loosing out on top end BHP if set up right (I think)

[Jimmyarm]

Dont forget that any needle suggested in vizards book or on Winsu is just a best guess, each engine is different and what works in one may not in another. Trying to 'guess' which needle will suit your engine by comparing it to 1275's just aint gonna cut the mustard.

It needs to go to the RR for them to choose the best one and modify it appropriately. This is probably even more important in this instance as its not really a 'standard' set up that you have there.

Maybe one of the hillclimbing boys runs something similar to you and could give an indication of what they use as a starting point so you at least get it moving !

[fikus01]

OH MY GOD i cannot believe i forgot to say that!! me who swaers by rolling road setups!! its luck jimmy saved my bacon there!! ROLLING ROADS RULE

[Jimmyarm]

We need a bot that spots posts asking about needles and auto responds with 'take it to a RR' then closes the thread !