OK pop-pickers, we’ve built our Vespa reedvalve engine out of left-overs (though not for the last time!) and figured out how to bolt it into a vintage Lambretta Lui. Now is the time to get cracking on the chassis…
First Dyno Test
Young lads and revvy motors. What a potent mix. No sooner had we cobbled the engine into the chassis, still with the original Lui forks, square 1960s front tyre and a complete absence of health & safety, before we took it up to the Diablo Moto/SLUK dyno to see how it ran.
The carburettor is a Chinese fake copy of a Taiwanese copy of Japanese Keihin PWK carb. It cost about £20 and comes with a bag of three main and pilot jets, none of which have markings. The old maxim I was told about tools was “If they aren’t proud enough to put their name on it then don’t use it”, but I don’t know how that translates to people who put other people’s names on their products (Koso in this instance).
I realise that I should know better but we wanted a 26mm carb, and it only cost £20 for heaven’s sake.
The dyno session proved that the engine started and ran, if not very lean on the original jetting. The ignition timing still needed Buzzwangling (we just lined up the marks on the stator and casing) but the handy LED lights on the Scootronics CDI were enough to tell us that the stator was working.
The exhaust is another left-over – a prototype exhaust by Mathias Scherer of Ludwig and Scherer, sent to test on my old race SS90 ‘Underdog’.
In the end Underdog ran better on Mathias’ ‘Franz’ exhaust because the prototype – which we’ll call ‘Ferdinand’ for convenience – was designed with higher-revving engines in mind than my Quattrini. When you consider that the mildly-tuned 1980s Pinasco 125 reed barrel on the SuperLui has even shorter exhaust timing, the two were never going to be really well suited.
VIDEO | Sam gets to ride SuperLui for the first time
Our target power output was 12hp. It made that on the first run despite scarily lean jetting and obvious unsuitability of the exhaust to the cylinder porting. More important than that was that it ran and someone got the chance to buzz up and down the farm. The concept was proven. Time to strip it all back down and build it again properly.
I married a stripper
Before going any further we needed to clean up all the old chassis parts prior to inspection and welding.
My friend Gibbo (James to the magistrates) has not long ago set up in business as Nuneaton Alloys and Powder Coating after closing his previous business; Camphill Chop Shop. Gibbo became famous (and on TV) a couple of years ago for kick-starting the recent craze of pimping old Honda C90 clunkers, turning them into mad bobbers and even making road-legal BMX-style versions using the powerful derivative pit-bike motors.
At his powder-coating business, Gibbo has a massive vat of evil powder-coat removal chemicals. How evil? Nasty enough to molest your mum and then dissolve her body afterwards. That level of evil.
This chemical bath proved very useful in cleaning all the coating off a painted Lambretta engine casing in about two minutes flat. It doesn’t take much longer to remove otherwise impervious powder-coating either, leaving a bare metal surface and not harming rubber or plastic in the process. Basically, if you live in the Midlands and want anything stripping then James is your stripper. Just tuck the money into his thong like you do at a real strip-club.
After this demonstration, we threw the Lui into the acid tank and sampled the full horror of what remained.
The scooter had obviously been sat under a leaky gutter for a decade or two. The seat bracket had turned to dust. You could poke holes in the fuel tank with your fingers and the two tubes that support the tank and seat were very pitted from rust. Luckily the legshields were not so badly affected with only a few places where you could see through rusty pin-holes.
The other revelation was that at some stage the floorboard struts had snapped off the frame; which is not uncommon on these lightweight Lambretta models. What is rarer is managing to persuade Stevie Wonder to take a break from a sell-out tour of Italy to get him to make welded repairs using a stick-welder while shivering after a dip in the sea. The quality of the welds and repairs was pretty shocking, with the legshield being welded directly to the strut in one corner. All that being the case, I wasn’t daunted at the prospect of improving it.
Incidentally, for anyone else with a Luna that has broken stand struts, remade weld-in sections are now available if you search eBay for ‘Lambretta LUI Vega Front Cross Member’. For us there wasn’t the time or inclination to do the job ‘that properly. Instead I fabricated repair sections from old bits of box-section steel, working from the thick bits of plate that Stevie used for reinforcement. It’s not my finest work, but we now had a fully functional chassis to build from.
Paint or Powder Coat?
At this point we had a key decision to make. Paintwork for scooters has got really expensive of late and even at mate’s rates you need to be looking at a few hundred quid to a grand depending on the complexity of the job. That’s fair enough; proper painting is extremely labour intensive and skilled.
Powder coating on the other hand, doesn’t offer such a good finish but equally, it’s reasonably easy and fast to get a decent finish as long as the base material underneath is in good condition.
Bear in mind that we have a friend who is a powder coater and was willing to show Sam the ropes so he could coat his own scooter. That pretty much made the decision for us.
All we needed now was some immaculate bare metal to coat…
As previously discussed, the original pressed steel Lui forks are barely up to the job of eating soft fruit, let alone suspending the front wheel of a 70mph scooter. They went straight in the bin (eBay).
The replacement set, that we’ve already found to be adaptable, come from a very bland Honda automatic scooter called a Bali. I rode one once and the front end was its most impressive feature. It’s got a 10” tubeless front wheel, trailing link forks like a Lambretta and most importantly a decent disc brake on an anti-dive linkage. Basically it’s got all the technology that we need in a package that doesn’t cost a gazillion pounds; like all the made-to-measure scooter stuff. You should still be able to pick up a full set of forks, brake and wheel for less that £100.
While the Bali fork stem is perfect to go in the Lui frame, the only major problem is that the fork legs are so wide you can’t actually turn. Unless you make recesses in the Vega legshield ‘straight on’ is your only directional option.
So, we chopped some holes in the legshields for clearance. As you do when you are grinder-happy.
Angle grinder, not Grindr.
It’s not wise to get them confused.
Tool-boxing, Round 1
If you’ve actually ever tried to use a Lambretta Lui in anger, or any other sort of mood to be honest, then you’ll have quickly met one hurdle. It has absolutely zero carrying capacity. Not even a little cubby hole for a bottle of oil. Presumably, in the old days, everyone would buy ‘Miscela’ (fuel and oil mix) directly from the fuel station, so there was no need to carry oil.
Nowadays when you are more likely to find tampons and wine for sale in a fuel station than you are 2-stroke oil, it is imperative to carry your own. So we needed a toolbox.
On Sam’s last Lui we welded a replica Lambretta D toolbox to the centre-beam and extended the edges to meet the legshields. This gave us a very stylish and practical legshield toolbox; which looked excellent – particularly once Dan from Total Revamp had filled all my ugly tack-welds before painting the scooter.
The problem with powder-coating the chassis is that ugly tack-welds would not do this time. All the welding needed to be smooth and blemish-free if it was going to look any good when powder-coated.
Hmm. I can weld, but can I weld to that standard?
Ding Ding, Round 2
So we have the toolbox trimmed to fit the centre-beam and in order to get a plan for the extensions we measure the gap between the toolbox edge and the legshields at various places, and then we add a bit. It’s all very scientific.
These dimensions allow us to cut some templates for steel sheet sections which are then folded inside the model D toolbox and MIG-welded on in a series of overlapping tacks. I’m sure someone trained in metalwork would do a tidier job, but this is the level I’m at through learning as you go.
After welding, Sam ground all the welds back as much as possible leaving a finish that wasn’t bad, but wasn’t good enough for powder coating either.
At this point I have to thank Luna fanatic and professional powder coater Graham McBear (of Two Brothers Powder Coating in Sheffield) for a solid gold tip. Traditionally you are not supposed to use any filler on parts going for powder-coating because the filler tends to shrink and crack when the powder is baked in the oven.
Graham had tried many different suggestions without success until a customer came to him with a part that he’d filled with JB Weld. For those who’ve never played with it yet, JB Weld is like Chemical Metal’s tough American relative. A muscle-bound cousin who is in the Marines and takes no shit from anyone, but probably has a micro-penis from steroid abuse.
Perhaps I’m over-thinking this.
Anyway, Graham told me – when we were buying a freshly-blasted Vega tank from him – that JB Weld is tough enough to stand the heat in the oven and would work to cover-up all the blemishes in my ground-back welding.
It was certainly worth a go, so we filled all the welds and sanded it all back again. In for a penny, in for a pound…
NEXT TIME: Sam powder-coats his scooter and we set about tuning the engine…
Some of the products mentioned in this feature are available through the SLUK Shop