phbh atomiser/needle advice needed.

[bluebob]

just looking for some advice about clip positions and how they work with different set ups.while trying to getthe jetting something like while running in I had an av268 with x7 needle in my 28phbh dellorto.starts great and ran great at least for running in.on checking plug colour found it too be very black and think I can safely come down a setting.as I am not near main jet position I figure reducing atomiser size made sense.so as I was on the leanest clip position I put in av266 thinking this would be a touch leaner even on the richest clip position.that was my logic which I now think is wrong as the engine now runs "lumpy" as I get toward half throttle were it previousl ran ok.at this point I open the choke which almost kills it,so I get the feeling I am now running richer than before and not that bit leaner I was looking for.so I am hoping someone can explain the logical sequence when fine adjusting .cheers.

[Warkton Tornado No.1]

Your instinct was right in anticipating that an AV264 would lean off the mixture compared to the AV268 but, unless the AV264 is badly worn oversize, all it served to prove was that AV264 was adequate & AV268 oversize....You should move the clip position back up the needle & try it again.

As I said only today, the best thing you could do to help the Forum in helping you, is to post back on here all the sizes of:

Choke jet
Pilot jet
Main jet
Slide
Needle & clip position
Number of turns out of the adjust screw
Float needle valve size

[martyn dwane]

Why not try An AV266 or a leaner needle with the 268 ?

[bluebob]

apologies for misleading you.now edited my mistake.meant to say I changed to a 266 (not 264).hope this makes sense now.
warkton thanks for the reply.i didn't put my set up on as I was looking for advice on what the logical sequence might be when fine tuning in the range of atomiser/needle.eg.as I was on the leanest clip setting on 268 should I maybe have gone for a leaner needle before going straight for a leaner atomiser.i am not clued up on variations in needle size,so this was the the kind of advice I was looking for rather than someone telling me exactly what I need for my set up as I would still be no wiser about how these parts work together.

[Warkton Tornado No.1]

Post by bluebob » Thu Jul 14, 2016 12:43 pm

apologies for misleading you.now edited my mistake.meant to say I changed to a 266 (not 264).hope this makes sense now.
warkton thanks for the reply.i didn't put my set up on as I was looking for advice on what the logical sequence might be when fine tuning in the range of atomiser/needle.eg.as I was on the leanest clip setting on 268 should I maybe have gone for a leaner needle before going straight for a leaner atomiser.i am not clued up on variations in needle size,so this was the the kind of advice I was looking for rather than someone telling me exactly what I need for my set up as I would still be no wiser about how these parts work together.

There’s one thing that most of us on here would seem to agree on & that would be to set up the pilot/airscrew/slide first, which was why I asked your settings...

If you think about it, you always have to go from tick-over up to whatever else you intend to ride @ then back down again.

It is an essential part of making any machine good to ride.

It is best not to put the ‘cart before the horse’ in these matters...

[Wack]

The x7 is the leanest of the commonly used x13 and x25 so I would go with the AV 266 and move the clip up one notch at a time until it runs clean.