Scooterotica

when jetting up a carb which do you change first the needle or the atomiser. let me be a bit clearer, PHBH30 carb, ive just changed from a AF fresco exhaust to a MB Clubman, previously i was running a AV266 with a X13 needle. It`s too rich with the needle on the top clip, so do i go to the next leanest needle or do i change the AV 266 to a AV264 with the X13 ?
given the time i will try both combo`s with plug chops but just wondered which way the Boys with Dyno`s would go and why .Probably my question is more pointed to Dan Or Sean, but others may have some reasoning as to which to change first.
Cheers.

I'll be interested in this too, I have the same on my Avanti, AV266, X13 and clip in the top position but still too rich.

If lots of people email Allstyles asking if they're intending to have Av265 and AV267 atomisers made, in the same way that they've had standard atomisers reproduced for the SH range then we might convince them that there is a suitable sized market for them.

I emailed them this request already!

Adam

Edited to correct previous error (doh!)

Don`t you mean AV265 Adam ?

^... We'll spotted Yamlam. Yep, AV265

I typed that response on my wife's tablet, for which you need the eyes of an eagle and the tiny fingers of a child!

Same here, but my Monza is running rich on a AV266 with X7 on top clip. But I'm going to try going down to a leaner AV264 and perhaps start with a richer X13 needle on middle clip and then see how it feels. Depending on how it feels, then I will adjust clip either up and down and hopefully fine adjust with half washers and plug chops.

Hoping to do this before the weekend so will post up results or picture of holed piston.

Part of the issue is that 266 to 264 is a big jump, with it being a case of rich to weak on many motors. As this relates to atomiser and needle shaft diameters, this is at lower throttle positions before the needle taper comes into play. Sure, going for a needle with a longer taper length will richen it sooner but a 265 atomiser would allow for the correct mix at this pre-taper throttle position.

Unfortunately, there are limited needle diameters with a profile that suits the typical Lambretta demands, making a needle swap less suitable. Reducing needle shaft diameter to suit is something that I do to better the situation but this leads to bespoke needles and introduces an extra margin of error. Accurate AV265 and 267 would be a go send!

Adam

am i right in assuming a AV264 has a 2.64 mm bore ? i know there measured in hundredths of a mm, if this is the case could one not be reamed ( oh er mrs ) out to 2.65 (AV 265) as precision reamers of this size are only about £15.00. if this is the case id gladly buy one and do a few .

Yeah, that's right. Obviously, accuracy is everything! If accurate readers are available then I'd buy not too

Adam_Winstone wrote:Yeah, that's right. Obviously, accuracy is everything! If accurate readers are available then I'd buy not too

You on your wife tablet again Adam