Tune or Replace?

[LambrettaMarky]

I'm thinking to fit this kit to my SIL GP200: https://www.lambretta.co.uk/shopping_cart.php. Would prefer to to go cast iron so it can be rebored if necessary in the future rather than a Nicasil set up.

With an intention to do more rallies & runs, my GP really runs out of puff ~60 ish & maybe 65 at a real push down a slope without luggage too. I've fettled it with high flow fuel tap, new Scootopia carb, new clutch pack & set timing to 17 BTDC now which seems best to me. It starts and runs fine, but I'm not comfortable of faster A roads running out of speed before the main traffic does, hence the kit.

I have very little scooter experience to call upon, so am really wondering whether a pukka Italian GP200 would be a better ride & investment over the SIL? They're more than double the price of mine, so perhaps naively I'm assuming they're a better ride mechanically too if well sorted?

My GP was essentially a new build, just left unused for some years so it is in lovely condition and I think a good basis to take further. I'd upgrade the wheels, tyres, brakes, clutch etc as appropriate for the kit too and can manage the work myself, so cost aside from the hardware is not an issue.

Thoughts and opinions from those more knowledgeable than me much appreciated.

[Nudger]

The link isn't working Marky

[LambrettaMarky]

Odd - seems OK on my PC.

https://www.lambretta.co.uk/shopping_cart.php

It's the GT240 Kit from Cam' Lam'

GT 240
Fits 200 cases
Peak Power Type Three
Peak Power - 18hp @ 6,800rpm
Speed - Cruise 75mph / Top 85mph
Recommended Carb - Dellorto PHBH.
Recommended ignition - Electronic / Variable.
Made in the UK, cast iron cylinder with reed valve, the GT kit uses Japanese pistons and comes with its own crankshaft to take it to 240cc. All kits are hand checked and finished by the manufacturer. The added benefit of reed valves makes a traditional cylinder more modern, efficient and cleaner running. Inelt is for the larger 26/28/30 PHBH manifolds, larger carbs with remote filters will offer more performance. The GT kit produces its torque quite low down the rev range, ideal for two up, touring etc. Defiantly needs your engine to be good, comes with its own crankshaft, ignition wise electronic, or better still a Varitronic.. Carb wise a 28mm phbh for a box pipe and slightly better mpg, or a 30mm PHBH for a touch more performance or if you use an expansion. Exhaust a Avanti ST on it will make a great touring bike with loads of torque, a JL 3 will give best touring power.

[Warkton Tornado No.1]

Before committing to anything, I’d thoroughly recommend you read Sticky’s kit book.

As for your plan, you appear to be a ‘hands on’ owner/rider/tuner so there’s many advantages to obtaining another engine case & building upon that. It means you stay mobile whilst engineering the replacement which will allow for a straight swap.

There are still occasional bargains out there to be had. I bought four small block cases (not all ‘empty’s) for £100 & WT No.2 bought a Schhhhpaneesh small block/big block transfers case for £30. Not that the bulk of the membership needs to scrimp & save like us Warkton Tornado’s……

[LambrettaMarky]

Thanks & I do have Sticky's books.

I'd do the work over the winter, so not concerned about being off the road as such.

[Covboy]

those figures seems low - my gt240 makes 22-24hp and 20lb/ft torque at 6500rpm - 30mm dellorto and TSR pipe.
thats straight out the GT box, not fettled.

I'd add that i think its a great kit too.

[LambrettaMarky]

those figures seems low - my gt240 makes 22-24hp and 20lb/ft torque at 6500rpm - 30mm dellorto and TSR pipe.
thats straight out the GT box, not fettled.

I'd add that i think its a great kit too.

Thanks for that CovBoy.

I'm of the opinion that I'll do the work to my existing GP, rather than spending >£10k and still feel the need to modify. I'd prefer to be able to keep working and improving it & feel that a pristine Italian GP may in fact prove detrimental to keep fiddling with it from an originality perspective. The SIL has no such heritage so is a blank canvas almost!

[Toddy]

Been running my GT240 for the last 5 years just on first oversize done a lot of trouble free miles on it good kit you may need to trench the casing for the crank , as for Italian , Indian I’ve had both not a lot of difference riding wise

[Cgt75b]

Have you considered the new RB 240 which doesn’t require the case being modified, just something else to look at/consider.

Good luck in your decision making.

[LambrettaMarky]

Been running my GT240 for the last 5 years just on first oversize done a lot of trouble free miles on it good kit you may need to trench the casing for the crank , as for Italian , Indian I’ve had both not a lot of difference riding wise

Thanks Toddy. Experience with Lambrettas I don't have, so appreciate your comments.

[LambrettaMarky]

Have you considered the new RB 240 which doesn’t require the case being modified, just something else to look at/consider.

Good luck in your decision making.

No, I hadn't considered it & looking in my Sticky book is it AF Rayspeed supplied? Cam' Lam' are a few minutes away so I'll be getting the kit from there.

Have tried to communicate with AF Rayspeed and given up, it's impossible!!

[missing lynx]

Thanks & I do have Sticky's books.

I'd do the work over the winter, so not concerned about being off the road as such.

But do you have the Kit book with the brown cover?

[Nudger]

Thanks & I do have Sticky's books.

I'd do the work over the winter, so not concerned about being off the road as such.

But do you have the Kit book with the brown cover?

Sticky's Kit Book would be a good read for you (it's an interesting read for anyone really). I have a GP with an AF Rayspeed Stage 4 barrel & solid mount 30mm carb, I think this is exactly what you'd be looking for. You could always source it via CamLam I'm sure. Alternatively, in the warmer months come along to some LCGB events and talk to people over a pint. Always a great source of real world experience.

[Adam_Winstone]

You really need to figure out what you already have as many, probably most, Indian GP200s will already have the SIL Stg IV factory tuned barrel. In which case you're probably half way there already! You may also find that you currently have the SIL big bore exhaust or a clubman fitted, which again would get you on the way to what you are looking to achieve.

As others have said, the Indian GP200 should be at least as fast as the Italian GP200. If the Indian one is factory spec' then, as mentioned above, it should already benefit from ported cylinder and performance exhaust, resulting in more BHP and a faster top speed.

One step you could go for before committing to any kit is to determine what you have and to consider swapping the standard 22mm carb for a 30mm PHBH Dellorto, which you would need if you decide to go for the GT kit in the future. This combo of what you may already have + 30mm carb is used by many and meets the requirements of said users.

NB: You're lucky to live close to Cambridge Lambretta as they're a great bunch and would be able to advise you on what you already have and then make suggestions as to which may you might want to go, then be able to supply said parts.

Having just ridden over 1200 miles to/from 5-Nations in Fort William with one of my riding group being on a SIL IV with clubman and 30mm PHBH, I know exactly how well these go. Indeed, I knew anyway as this is a combo that I and many in my club have used for years. That said, the GT kits are excellent too... but another level of performance again. It all depends what you want.

Good luck, welcome to Lambretta and take care with anything you do.

Adam

[LambrettaMarky]

Thanks & I do have Sticky's books.

I'd do the work over the winter, so not concerned about being off the road as such.

But do you have the Kit book with the brown cover?

Yep!

[LambrettaMarky]

Thanks & I do have Sticky's books.

I'd do the work over the winter, so not concerned about being off the road as such.

But do you have the Kit book with the brown cover?

Sticky's Kit Book would be a good read for you (it's an interesting read for anyone really). I have a GP with an AF Rayspeed Stage 4 barrel & solid mount 30mm carb, I think this is exactly what you'd be looking for. You could always source it via CamLam I'm sure. Alternatively, in the warmer months come along to some LCGB events and talk to people over a pint. Always a great source of real world experience.

Interesting, thank you.

I believe my GP has the Stage 4 barrel & it has a clubman exhaust. It's actually a really sound motor with zero miles until I got it so a grand total of <1,000 miles still now. Mechanically it feels fresh and good. I've x6 two strokes and have tuned a fair few LC's so have a feel for a ropey motor..

The 30mm carb option is a quick win for sure and simple enough to get from Cam Lam. If just the carb' gives me what I'm after I'll be chuffed.

[LambrettaMarky]

You really need to figure out what you already have as many, probably most, Indian GP200s will already have the SIL Stg IV factory tuned barrel. In which case you're probably half way there already! You may also find that you currently have the SIL big bore exhaust or a clubman fitted, which again would get you on the way to what you are looking to achieve.

As others have said, the Indian GP200 should be at least as fast as the Italian GP200. If the Indian one is factory spec' then, as mentioned above, it should already benefit from ported cylinder and performance exhaust, resulting in more BHP and a faster top speed.

One step you could go for before committing to any kit is to determine what you have and to consider swapping the standard 22mm carb for a 30mm PHBH Dellorto, which you would need if you decide to go for the GT kit in the future. This combo of what you may already have + 30mm carb is used by many and meets the requirements of said users.

NB: You're lucky to live close to Cambridge Lambretta as they're a great bunch and would be able to advise you on what you already have and then make suggestions as to which may you might want to go, then be able to supply said parts.

Having just ridden over 1200 miles to/from 5-Nations in Fort William with one of my riding group being on a SIL IV with clubman and 30mm PHBH, I know exactly how well these go. Indeed, I knew anyway as this is a combo that I and many in my club have used for years. That said, the GT kits are excellent too... but another level of performance again. It all depends what you want.

Good luck, welcome to Lambretta and take care with anything you do.

Adam

Thanks Adam.

I'll go get a 30mm PHBH from Cam Lam tomorrow if they have one and will try that before going big bore. I'm not after a ton up monster as I have other bikes to go fast on, so just maybe this will be enough to get me to the rallies in 2025.

I really appreciate the advice - Cheers!

[Adam_Winstone]

Don't forget that you will need a manifold and throttle cable to suit this new carb. FYI - The carbs are available in rubber mount or solid mount options and you'll need a rubber mount version (and manifold) so that the carb is compatible with the GT kit, if you decide to upgrade in the future.

Let Cambridge know exactly what you are looking to do so that they can ensure that you leave with any sundries that you might need; carb rubber, clips, gasket, JETS, etc.

[LambrettaMarky]

Don't forget that you will need a manifold and throttle cable to suit this new carb. FYI - The carbs are available in rubber mount or solid mount options and you'll need a rubber mount version (and manifold) so that the carb is compatible with the GT kit, if you decide to upgrade in the future.

Let Cambridge know exactly what you are looking to do so that they can ensure that you leave with any sundries that you might need; carb rubber, clips, gasket, JETS, etc.

Will do Adam - Thank you.

I'd like an expansion chamber exhaust as much for aesthetics perhaps - would that help the 30mm carb set up and any ideas which one?

Cheers.

[Adam_Winstone]

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.