Tune or Replace?

[LambrettaMarky]

Some expansions fit better than others, often requiring panels / runners to be trimmed even they say they don't. However, the biggest issue with any change of exhaust, whether it be expansion or box pipe, is that they vary dramatically as far as the rev range that they work well at, often requiring the gearing to be changed to suit. Some high-powered exhaust will only produce an increase at much higher revs, which often results in motors going slower if the porting of barrel/kit doesn't suit it. You could easily spend £450+ pounds to go slower (lol)!

Also, be warned that people's opinion of pipes differs wildly too, depending on how they like to ride. It is very easy to make the wrong decision based on the advice of others who like a different output.

Take great care to note that peak BHP means very little on anything but a dyno! If you look at dyno charts of pipe performance then you should consider the breadth of power delivery; what is the BHP spread from low rpm, through the mid range and at what RPM the power starts to drop off again.

Listen to others but look for advice that comes up time and time again so that you get an appreciation of what the majority opinion is. Also, discuss with Cambridge and listen to what they tell you, trying to understand the differences they explain to you.

Good luck.

Thanks again Adam for your words of wisdom.

I've been over to Cam Lam and done some shopping:

JL3 30mm PHBH by KTM Marky, on Flickr

Essentially I got the 30mm carb & jetted to suit as a starter, plus the manifold, rubber mount, throttle cable, etc. I also got the JL3 exhaust. We agreed that should I go for the GT240 kit then all of this will move across, so half way house type of thing..

JL3 by KTM Marky, on Flickr

Now to work...

[Toddy]

Nice one your going to be busy then, did cam lam recommend the JL 3 I run a race on minewhich was recommended by the supplier due to port timings and has been great good luck with the build

[LambrettaMarky]

Nice one your going to be busy then, did cam lam recommend the JL 3 I run a race on mine which was recommended by the supplier due to port timings and has been great good luck with the build

Cam Lam agreed it'd work with the 30mm PHBH for both the Stage 4 that I have now and again with the GT should that be next.

[Toddy]

I see sorry misread your post good luck

[LambrettaMarky]

As nice as the paint looks I'm told it'll be off in a mile, so will take it for a Cerakote treatment once I've checked the mechanical fit.

[Adam_Winstone]

Nice combination of parts for a reliable fast tourer. Get everything set up correctly and I think that you'll be pretty happy with the outcome.

That said, many Lambrettas go on a personal journey into Lambretta tuning by starting with just such a setup, loving the performance gains and then going further and further into the world of tuning. However, most of us then take things too far and realise that a simple setup like this was not far off the best of both worlds.

Keep talking to Cambridge about setup. They'll have got you somewhere close for carburation but do note that you'll want to strobe check your ignition timing, then making any adjustments required; getting the ignition timing suitable for your setup will help to keep the motor cool and to avoid seizures.

Nice bits

[Covboy]

As nice as the paint looks I'm told it'll be off in a mile, so will take it for a Cerakote treatment once I've checked the mechanical fit.

I used Cermacote on a SX project I did ( blog on here somewhere) I would say its not worth it personally. It pinholed and rusted.
The TSR on my GT240 has had a few coats of the cheapest BBQ paint and its been fine.

[LambrettaMarky]

Nice combination of parts for a reliable fast tourer. Get everything set up correctly and I think that you'll be pretty happy with the outcome.

That said, many Lambrettas go on a personal journey into Lambretta tuning by starting with just such a setup, loving the performance gains and then going further and further into the world of tuning. However, most of us then take things too far and realise that a simple setup like this was not far off the best of both worlds.

Keep talking to Cambridge about setup. They'll have got you somewhere close for carburation but do note that you'll want to strobe check your ignition timing, then making any adjustments required; getting the ignition timing suitable for your setup will help to keep the motor cool and to avoid seizures.

Nice bits

Thx Adam.. I’m going to try to get this as right as I can before going for a kit..

I’ve a strobe and will check timing as you suggest.. I will also put a VAPE on it once this phase of work is complete as I want DC outputs for stuff like a sat ban, LED headlight and SIP speedo..

[LambrettaMarky]

As nice as the paint looks I'm told it'll be off in a mile, so will take it for a Cerakote treatment once I've checked the mechanical fit.

I used Cermacote on a SX project I did ( blog on here somewhere) I would say its not worth it personally. It pinholed and rusted.
The TSR on my GT240 has had a few coats of the cheapest BBQ paint and its been fine.

Interesting. I’ve used HT rattle cans on my LC pipes and they’re fine to be fair…

[Warkton Tornado No.1]

As you are familiar with motorbikes & - no doubt - two stroke tuning, then you are probably aware of the guides available for carburettor set-ups. Dell’Orto have excellent guides that go in depth into the whole spectrum of how the individual components operate & overlap to provide optimum fuelling from tickover to WOT.

Dell’Orto manufacture some excellent carburettors & some are designed specifically from their conception to be two stroke specific, obvious most notablably via the shape/section of the guilotine referred to as the slide. However, within the range, say a swap from VH to PH (or vice versa) then the actual sizes of jets, atomisers, slide cutaway would prove almost identical.

There is definitely a pre-occupation with road-going Lambretta tuning in the use of the PH carburettor & I have stated my reasoning upon this Forum previously as to why I’m not personally a fan. That said, in over five decades of continuous ownership & building/setting others’ engines, I have yet to encounter the need for an atomiser any greater than 268 & even that extensively modified engine ran well with a 266. (The ‘safer’ option of 268 was only adopted as the quality of fuel to be used could not be assured, unlike Avgas)

I must be missing something as to why a 270 atomiser would be advocated for use in the kind of tunes that has been mentioned in this Post…….

[LambrettaMarky]

As you are familiar with motorbikes & - no doubt - two stroke tuning, then you are probably aware of the guides available for carburettor set-ups. Dell’Orto have excellent guides that go in depth into the whole spectrum of how the individual components operate & overlap to provide optimum fuelling from tickover to WOT.

Dell’Orto manufacture some excellent carburettors & some are designed specifically from their conception to be two stroke specific, obvious most notablably via the shape/section of the guilotine referred to as the slide. However, within the range, say a swap from VH to PH (or vice versa) then the actual sizes of jets, atomisers, slide cutaway would prove almost identical.

There is definitely a pre-occupation with road-going Lambretta tuning in the use of the PH carburettor & I have stated my reasoning upon this Forum previously as to why I’m not personally a fan. That said, in over five decades of continuous ownership & building/setting others’ engines, I have yet to encounter the need for an atomiser any greater than 268 & even that extensively modified engine ran well with a 266. (The ‘safer’ option of 268 was only adopted as the quality of fuel to be used could not be assured, unlike Avgas)

I must be missing something as to why a 270 atomiser would be advocated for use in the kind of tunes that has been mentioned in this Post…….

Interesting…. Cam Lam mentioned 268 wasn’t available and they didn’t know of any stock either hence the 270 (for now). If you know of the whereabouts of a 268 do please let me know, Cheers.

[Storkfoot]

Until the last year or so, I’d have agreed with WT about the 270 on either a PHBL or PHBH. But, I have a Casa 192 with a PHBL25 and a standard mushroomless GP200 exhaust. I think the salient point with my attempts at jetting it was the fact that it didn’t like a 40 slide, it liked a 45. I ended with 48 pilot; D29/2; AQ270: Main 100. I even went to the added expense of buying an AQ269 but, no, it ran weak at one point in the mid range.

My TS1225 runs a PHBH30 with an AV268, whilst my Stage 4 200 (PHBL25) didn’t like the 45 slide/ AQ270, it runs a 40 slide and AQ266.

[Warkton Tornado No.1]

Dell’Orto have excellent guides that go in depth into the whole spectrum of how the individual components operate & overlap to provide optimum fuelling from tickover to WOT.

I must be missing something as to why a 270 atomiser would be advocated for use in the kind of tunes that has been mentioned in this Post…….

Within the guides I’m referring to, the calculation for the required atomiser size is relatively easy to do. It would appear that Dell’Orto themselves & my own experience would contradict any situation where such a large atomiser would be necessary. A good Group IV Lambretta will produce in excess of 25 BHP even in OEM cast iron, four port form. The VHSC 38 mm carburettors we last used had main jets around 145 & atomisers 265.

It would be interesting to hear how an engine runs with a 270 atomiser but no main jet, then the same test with a 264, especially in an engine utilising a main jet as small as 100.

[LambrettaMarky]

Until the last year or so, I’d have agreed with WT about the 270 on either a PHBL or PHBH. But, I have a Casa 192 with a PHBL25 and a standard mushroomless GP200 exhaust. I think the salient point with my attempts at jetting it was the fact that it didn’t like a 40 slide, it liked a 45. I ended with 48 pilot; D29/2; AQ270: Main 100. I even went to the added expense of buying an AQ269 but, no, it ran weak at one point in the mid range.

My TS1225 runs a PHBH30 with an AV268, whilst my Stage 4 200 (PHBL25) didn’t like the 45 slide/ AQ270, it runs a 40 slide and AQ266.

Thanks Paul & I’m sure there will be some fettling to get the settings right. I’ll stick with the Cam Lam suggestions as a base & go from there..

[LambrettaMarky]

Dell’Orto have excellent guides that go in depth into the whole spectrum of how the individual components operate & overlap to provide optimum fuelling from tickover to WOT.

I must be missing something as to why a 270 atomiser would be advocated for use in the kind of tunes that has been mentioned in this Post…….

Within the guides I’m referring to, the calculation for the required atomiser size is relatively easy to do. It would appear that Dell’Orto themselves & my own experience would contradict any situation where such a large atomiser would be necessary. A good Group IV Lambretta will produce in excess of 25 BHP even in OEM cast iron, four port form. The VHSC 38 mm carburettors we last used had main jets around 145 & atomisers 265.

It would be interesting to hear how an engine runs with a 270 atomiser but no main jet, then the same test with a 264, especially in an engine utilising a main jet as small as 100.

I’ll post up a ride report when i get to that bit! Do you have a link to the guide or is Google sufficient?

[Warkton Tornado No.1]

Here’s a link to a basic guide:

https://www.dellorto.it/wp-content/uplo ... manual.pdf

This link goes into more detail:

http://danskkartingcenter.dk/dellorto_m ... _guide.pdf

Interesting example of main jet size selection given based upon atomiser on page 16…..

[LambrettaMarky]

Here’s a link to a basic guide:

https://www.dellorto.it/wp-content/uplo ... manual.pdf

This link goes into more detail:

http://danskkartingcenter.dk/dellorto_m ... _guide.pdf

Interesting example of main jet size selection given based upon atomiser on page 16…..

Super - Thank You - I'm always interested in learning!

[roli150lam]

try wasp performance Heysham for av268 atomiser

[LambrettaMarky]

try wasp performance Heysham for av268 atomiser

Will do - Thanks for the tip as I've never heard of them.

[LambrettaMarky]

..I could just type Dellorto AV268 Atomiser into eBay of course and problem solved!