Well, the biased needles were introduced as part of the emissions control.
Some carbs were not adjusted properly and the rigidly fixed needle in the
piston dragged on the jet causing mixture problems, and therefore caused
emissions problems. A well aligned needle was fine, but if it were misaligned,
it was a problem.
By "soft-mounting" the needle, and intentionally allowing it to drag on the
jet, there was more room for misalignment of the needle and emissions did not
suffer.
BUT since the "biased" needles intentionally drag on the jet orifice, they also
will ALWAYS cause wear of the needle and jet. I have a set of biased needles
on my TR7, and I had to change the needles because the mixture at the upper end
was too lean. When I removed the needles I found that there was already
significant wear after only a couple of 1000 miles!!! I had also made the jets
as perectly centered asI could. I centered the jets just like a fixed needle
carb so that they were as centered as you can get.
I decided that biased needles are a load of BS and decided to eventually make
or find adapters to turn biased types of needles into rigid types.
MGBMGA.COM has a brief note on their website that they have some sort of
adapter, but they do not explain further. I am awaiting a response to an email
I sent late last night. Maybe they already have what I am looking for.
So, it is good that you do not know what a "biased" needle is, and hopefully,
having a TR3, you never need to find out. But, if you get some new carbs, you
will get a surprise the way I did!!!
-Tony
-------------- Original message --------------
Hi,
What is a biased needle?
I've yet to get my TR3A running but, I think it has SM or TW needles. I've
heard of other viarations but not sure what a biased needle would do.
Thanks,
Paul
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