Advice

[Simon_T]

Hi all,
I feel I'm almost there with my jetting except for pulling away. It feels like its still rich.
Now do i change the pilot jet or do i change the needle or needle and atomiser combination. At present i have an x4 top clip and 266 atomiser and 53 pilot.
Cheers.

[coaster]

You'll need to post a lot more information than that if you want any sort of meaningful advice What engine is it, exhaust, ignition, has it got a top end kit fitted (Mugello/TS1/GT etc.) or is it standard and what carb is that, make model and size.

Needles don't usually come into effect until 1/4 throttle, before that it is down to the air screw, idle jet and slide.

Colin

[Simon_T]

Small block mugello 198.
JL 1 exhaust
dellorto 28mm open mouth

choke 50
pilot 53
slide 40
main 116
float needle 300
x4 needle top clip
266 atomiser
17 degrees timing static

seems to struggle pulling away then clears up but not crisp then wot seems to take off.

[MickYork]

The main seems a bit lean at 116 but that wont explain the low down issues (although it would explain why it's quick on the top end).

Is the atomiser an AS or AV ? the x4 needle is not commonly used on a Lambretta so not too sure about the needle

I had a similar issue on my Avanti and fitted an auto retard unit (M-Tech) which cleaned up the lower end.

[coaster]

I'm not familiar with that atomiser/needle combo so not able to comment, hopefully someone else will be along to comment. Your pilot is in the right ball park though but the choke would normally be a 70, fairly standard for Lambretta set ups. WOT btw is only using the main jet so the atomiser/needle will have played their part by then.

[Warkton Tornado No.1]

In response to your question (which is relevant to your existing set-up) I would suggest you need to establish the number of turns out that the mixture screw is set. Somewhere between about half & 3-1/2 may be what you find.

The mixture screw works in conjunction with the pilot jet & it appears that you need a smaller size.

If I were you I would try a ‘50’ with the mixture screw about 1-1/2 turns out & go up or down from there.

[Simon_T]

Atomiser is av266 a guy called peter bowden who works at cam lam gave me these to work on.
the x4 is on recommendation from him also.

[coaster]

Pete SHOULD know what he's talking about but I can't recall anyone mentioning use of an x4 needle before there are far more knowledgeable folk on here that may have knowledge of your combination.

[Warkton Tornado No.1]

Post by coaster » Mon Aug 29, 2016 5:15 pm

Pete SHOULD know what he's talking about but I can't recall anyone mentioning use of an x4 needle before there are far more knowledgeable folk on here that may have knowledge of your combination.

Agreed, but I’m glad you said it

Once the bottom range is sorted, X2, X7, X12 & X13 would be my own natural choice of needle as they are all Ø2.5 to Ø1.8 with varying tapers.

[Simon_T]

Pete SHOULD know what he's talking about but I can't recall anyone mentioning use of an x4 needle before there are far more knowledgeable folk on here that may have knowledge of your combination.

Its on Facebook mugello owners page in files x4 is same as x7 x13 except for taper is 2.48 180 20 where as the others are 2.50 180 20, 22 or 24.
all though i think he quoted me those settings with a clubman exhaust on not the jl

[Simon_T]

http://www.bristollambretta.com/dellortojettingneedles.htm


https://www.facebook.com/notes/lambretta-mugello-performance-kit/jetting-specs-mugello/927986100597629

[Warkton Tornado No.1]

Post by Simon_T » Mon Aug 29, 2016 5:50 pm

coaster wrote:
Pete SHOULD know what he's talking about but I can't recall anyone mentioning use of an x4 needle before there are far more knowledgeable folk on here that may have knowledge of your combination.


Its on Facebook mugello owners page in files x4 is same as x7 x13 except for taper is 2.48 180 20 where as the others are 2.50 180 20, 22 or 24.
all though i think he quoted me those settings with a clubman exhaust on not the jl

If the figures listed for Dell’Orto needles, X or otherwise, have any significance, why would the Ø A be 2.5 in some instances yet 2.46 to 2.53 for others if it had no consequence?

You may be correct, but until convinced otherwise, the difference between an X4 & X7 (fully in the atomiser) to my mind remains @ 0.078 square mm.

That may only be half a nat’s but narrowing the field down does help when it comes to the limited capacity of my brain & resources...

[Simon_T]

Post by Simon_T » Mon Aug 29, 2016 5:50 pm
No Idea..

coaster wrote:
Pete SHOULD know what he's talking about but I can't recall anyone mentioning use of an x4 needle before there are far more knowledgeable folk on here that may have knowledge of your combination.


Its on Facebook mugello owners page in files x4 is same as x7 x13 except for taper is 2.48 180 20 where as the others are 2.50 180 20, 22 or 24.
all though i think he quoted me those settings with a clubman exhaust on not the jl

If the figures listed for Dell’Orto needles, X or otherwise, have any significance, why would the Ø A be 2.5 in some instances yet 2.46 to 2.53 for others if it had no consequence?

You may be correct, but until convinced otherwise, the difference between an X4 & X7 (fully in the atomiser) to my mind remains @ 0.078 square mm.

That may only be half a nat’s but narrowing the field down does help when it comes to the limited capacity of my brain & resources...