LCGB Forums

I know this subject seems to come up virtually every week, but I wondered if you could help me interpret the feel on my Lambretta. Here's the details...

It's an LI150 Series 2 with RT195 top end. I've recently fitted an Avanti Ex-box exhaust (not straight-through) and it also has a 28mm Dellorto.

This has the following:

* Needle = X7 (two clips from top)
* Slide = 40
* Air Screw = 1.5 turns out
* Main Jet = 125
* Choke = 70
* Pilot = 55
* Atomiser = AV266

It starts second kick every time, choke for 20 seconds and then ticks over fine.
When riding, it is a little "chuggy" at lower revs but really not too bad and I could live with it. When full throttle it goes very well and really flys along nicely.

The main issue is between the two and it feels a little like it is 'holding back' and I am not experienced enough to work out whether that means it is running weak at that point. I'm therefore not sure whether I should try moving the clip to the top, or even change the needle to X13?

Any other suggestions from those much more knowledgeable than me?

Have you done any plug chops at all throttle positions?
My first thoughts are that you are too large on both the main and pilot jets. I would have thought that on a 195 with a 28mm phbh, 118-120 main and 50-52 pilot would be closer and that you may be running too rich. An X13 would make it even richer but as I said, you can check all this with plug chops BEFORE, changing any jets.

Thanks Rich. I did originally start off with a 118 main jet.

In terms of plug chops, no I haven't done this (to be honest I have absolutely no idea how too).
I had also changed the atomiser FROM an av264 to an av266 as I understand putting the 264 with an X7 needle could be too weak and I didn't want to cause any issues.

I have a similar set up with my 195 kit and 28mm dolly.
Chugging around 1/4 throttle yet once past this it pulls very well indeed.
Av266
X7 2nd clip from top
118 main
48 idle
60 choke
40 slide
Running BSM air filter through air box with inner tube removed
BSM carb to filter bellows
I have noticed that under the idle jet is another atomiser.
B62
Unable to find any information regarding changing this part
Any advice welcome

I presume you both have static timing also? (17 deg BTDC, no adv / retard CDi)

hullygully wrote:I presume you both have static timing also? (17 deg BTDC, no adv / retard CDi)

Yes static timing, BGM stator & CDI .
Set at 17 using a strobe light

probs why it chugs @ 1/4 throttle then bud, around town? or below 40mph?

My RT setup 28 delly, bgm V1 box
Pilot 48
Fuel screw 2.5 turns out
Choke 70
Main 118
Needle X7 top clip
Atomiser AV264
Slide 50
Float 3.5g
Float Needle Jet 300

hullygully wrote:probs why it chugs @ 1/4 throttle then bud, around town? or below 40mph?

I would say around town it's chugging, clears quickly enough when I am able to twist the throttle open a bit more.
Going to check the timing tomorrow.
Do you suggest a change of the static timing?

ULC Soulagent wrote:My RT setup 28 delly, bgm V1 box
Pilot 48
Fuel screw 2.5 turns out
Choke 70
Main 118
Needle X7 top clip
Atomiser AV264
Slide 50
Float 3.5g
Float Needle Jet 300

Thanks
Going through the air filter box or open carb ?

Mines pretty similar to ULC soul agent through a breathsweet- my pilots richer.

If you want to gain experience - change one thing at a time, get a feel for what the changes do and write it down so you don’t forget it.
Try richening the mid range and see what happens as you have the needle- then weaken it.

Meds wrote:Mines pretty similar to ULC soul agent through a breathsweet- my pilots richer.

If you want to gain experience - change one thing at a time, get a feel for what the changes do and write it down so you don’t forget it.
Try richening the mid range and see what happens as you have the needle- then weaken it.

Been making notes on all changes ( one at a time) and spread over a number of days, so as to not hack off the neighbour's and those who live along my test route.
And more importantly to keep my sanity
Boxes of idle,main jets plus needles.
Weekend away from road testing, just checking over nuts and bolts etc.
Completely new build from the ground up.

duncan1958 wrote:

ULC Soulagent wrote:My RT setup 28 delly, bgm V1 box
Pilot 48
Fuel screw 2.5 turns out
Choke 70
Main 118
Needle X7 top clip
Atomiser AV264
Slide 50
Float 3.5g
Float Needle Jet 300

Thanks
Going through the air filter box or open carb ?

Oh through a chiselspeed mx green filter