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Posted: Wed Sep 19, 2007 9:28 pm
by bmcecosse
Not too bad - be sure to do various trials and post up results! I would also select a needle that's a bit richer in that middle section - and try that! Or of course - you can just modify a needle that you know is no use - needle in leccy drill and fine file to 'adjust'.
Posted: Wed Sep 19, 2007 10:21 pm
by winger300
More question,
I'm using needle AAU which WinSU suggests
AAU is 0.7% lean on top end and 2.9% lean on mid range.
The closest being...
ABD is 0.7% lean on top end and 0.5% lean on mid range.
At 60mph in 4th gear, what section of the needle does this compare? And since it is consistently lean across the whole needle, can I adjust for this by setting the idle mixture a little richer?
Posted: Wed Sep 19, 2007 10:48 pm
by bmcecosse
The piston height will depend on the spring strength! It should be such that the piston is right up when running near full power with full throttle. Only way to know is to run it on a RR and watch what happens. Easier on a Mini - can take the centre speedo out - and look directly into the carb while charging along. Your 60 mph in 4th gear will vary wildly depending on whether flat road no wind/climbing hill and/or head wind or downhill and/or tail wind! Just select a needle that's thinner about 1" down from the base - or take a useless needle and make it thinner. On the HIF i'm not sure that adjusting the idle does follow over the range - it certainly does on the older carbs. These HIFs also have a thermostatic device inside which leans out as it gets hot - maybe this has gone wrong ?