Ron Moss - Avanti TT3 - Cylinder Kit - Review & Test.....

[Jazzy]

With the benifit of EGT gauge I found wit av 266 and x7 there's a weak spot on the "shank" of the needle.
Now running x4 tip clip much happier.

[rosscla]

Did you check the diameter of the needle at that point? There was a thread somewhere about out of spec needles.

[coaster]

Did you check the diameter of the needle at that point? There was a thread somewhere about out of spec needles.

I remember that too, it was one of Adam's I think.

[Jazzy]

No way of knowing as the needle is now mixed with other x7,s
Iirc it was silver rather than the bronze colour.

[mark1]

Adam,

can you recommend some jetting advice using the 266 atomiser. I've had a play around with different pilot jets but didn't get any joy.

[Adam_Winstone]

I'd have to strip my carb to check, it has not needed to be stripped for such a long time that I can't remember what is in there! That said, mine does run rich in places too, so don't expect mine to be spot on, but I like to run mine somewhat rich so that I have a reasonable safety margin for an air leak or tank of hot burning fuel when I'm on a long run.

I'll strip the carb at some stage and let you know what's in it.

Adam

[warts]

A further addition to the discussion in variation in needle sizes:
There is such a thing as a micrometer for carb jets. A bloke on one of the brit bike sites has one. He did a check of a load of what were nominally the same size jets to the manufactures specification.
Needless, the genuine manufacture's jets were most consistent, good but not spot on. Amal and Kehin showing better (can't remember if there were any Mikuni's). The knock off copies less so, generally the better known, like OKO, doing better than ebay specials - I bet that is a surprise!
He also did some calculations on flow rate, to see what effect the % change could have on mixture strength. It is not surprising from his measurements, that a set of published set sizes which works for one bike, would not necessarily do the business for another.


Should you want to have a look, do a search on Magnetoman on the Brit Bike Forum. You may have to register to search.

[coaster]

There was mention in Scootering a few editions back about someone that was having jets and atomisers remade due to variable quality from OEM's

[Jazzy]

then throw a couple of hundred litres of fuel thru and have the needle bouncing around inside the atomiser for a couple of thousand miles and your back to a pig in a poke.

Also the delerotto (sic) official line is the number on the jet relates to flow rate rather than hole size.
unless we build a test rig with the same static head as they use how can we measure.

Back on topic, love my Avanti ti bits

[warts]

So they test and calibrate each and every one?