carb/ ignition probs

[a-teamlambretta]

Having trouble setting up my rapido 240 reed valve motor. It's not reving out as it should.new varitronic ignition fitted and set at 24 deg st a fast idle and when reved it retards as it should. Have tried bgm stator and Indian flywheel prior to this and standard Indian set up. I have a vhsh 30 carb, same carb with all previous ignition set ups. I now have another vhsh to try. Can someone give me some ball park carb setting. Here is the motor set up
Rapido 240 Lth reed conversion
Varitronic ignition
B-race expansion

I need to know what slide,needle, atomiser,main,choke and idle jets.

It starts idlesand revs out ok up until 3/4 onwards. So I can only presume it'd carb set up. Cheers Simon

[MickYork]

Could be a few things besides what you've said. I'd change plug and cdi unit 1st then also consider the reed petals....

[a-teamlambretta]

Tried new plugs and as said this is the 3 ignition to be tried including cdi's

[a-teamlambretta]

When watching the flywheel with strobe it looks good not wandering or flicking about

[coaster]

......I need to know what slide,needle, atomiser,main,choke and idle jets.

What have you got in there at the moment?

[a-teamlambretta]

I want to try the new carb, will swap all jets over etc but just wanted to make sure what I had in there was right. Will have a look and report back

[a-teamlambretta]

Here is carb set up

Slide 40
150 main
60 choke
55 Idle
Dq 265 atomiser
K3 or 13 can't see need a magnifying glass
300 float

What do you think?

[dscscotty]

When you say reed 240, what has been done to the cylinder?, has a boost or boost ports been added? Piston modifications? 150 main seems a little big?

[a-teamlambretta]

Yes Work has been done. Single boost port no holes in piston but cut arche in piston skirt. Reeds are new. Motor sounds fit until 3/4 throttle, this on the stand not out on road. Ain't got front brake hooked up yet

[foremanbob]

isnt anything like this is it? this only happened as the throttle was opened up

This was a dodgy pickup on a BGM stator that I replaced with a Ducati pickup, and all was good

https://www.youtube.com/watch?v=A8eaScGexBA

[a-teamlambretta]

isnt anything like this is it? this only happened as the throttle was opened up

This was a dodgy pickup on a BGM stator that I replaced with a Ducati pickup, and all was good

https://www.youtube.com/watch?v=A8eaScGexBA

As stated, It's a varitronic ignition.

[johnnyXS]

24 degrees at fast idle is I believe max recommended advance .Your particular scooter spec may not be able to fully utilise that much total advance
I would be tempted to back the advance of 2 degrees and try that first to see if there was any improvement before messing with the jetting.
http://www.lambretta.co.uk/downloads/varitronic-fitting.html

[a-teamlambretta]

24 degrees at fast idle is I believe max recommended advance .Your particular scooter spec may not be able to fully utilise that much total advance
I would be tempted to back the advance of 2 degrees and try that first to see if there was any improvement before messing with the jetting.
http://www.lambretta.co.uk/downloads/varitronic-fitting.html

dont think its timing or ignition related as when i first started the motor i could not get any where near the sugested timings as the stator was fully clockwise. then i remembered i had changed the crank (time laps of a couple of years ) so re marked tdc which is around 40 deg clockwise from previouse setting ( keyway out on crank or flywheel??) anyway does not realy mater where the marks are. but ran the motor and still the same . the only thing that i have not changed is the carb hence wanting to try that before i pull the motor out. like i say the motor sound realy good until 3/4 and after throttle . will try and video it later and will nock the timing back to 21deg, thought it was 24 for some reason can see it making a shits worth of difference.

so what about carb settings ?? are they in the right ball park ?? . cheers for the input so far. simon

[Fred]

I'd come down on the main to 140 -145 see if it revs out

[weeks]

When you say reed 240, what has been done to the cylinder?, has a boost or boost ports been added? Piston modifications? 150 main seems a little big?

I'd come down on the main to 140 -145 see if it revs out

As your only revving out on the stand this has got to be the easiest try

[a-teamlambretta]

When you say reed 240, what has been done to the cylinder?, has a boost or boost ports been added? Piston modifications? 150 main seems a little big?

I'd come down on the main to 140 -145 see if it revs out

As your only revving out on the stand this has got to be the easiest try

will give it a try tonight

[Wack]

You will find that on a Varitronic , it hits a brick wall in neutral and will not rev out almost feels like you have blocked the exhaust. Wait till you get out on the road and I'm pretty sure it won't do it.

[missing lynx]

it could be the exhaust

[a-teamlambretta]

it could be the exhaust

Had a change of exhaust, was dev-tour now B-race, no difference.

[a-teamlambretta]

You will find that on a Varitronic , it hits a brick wall in neutral and will not rev out almost feels like you have blocked the exhaust. Wait till you get out on the road and I'm pretty sure it won't do it.

I have used a varitronic before with an imola and dev-tour, can't remember if was like this??.