Feature Scooter: Repsol Lambretta
When a scooter project requires extreme modification, carrying out precise engineering procedures can give quite stunning results
When a scooter project requires extreme modification, carrying out precise engineering procedures can give quite stunning results. This scooter is just that, stunning.
When a custom scooter is being built, it usually works around a standard set of rules. Frame and component modification, paint, engine, etc. Though there may be some form of engineering required, usually it’s just working around what’s already there. By adding something alien to the format then it requires a completely different way of thinking. So what would that component be, perhaps an engine? That has been done before, the prime example being a Yamaha YVPS engine fitted into a Lambretta, a conversion done several times and with great results. What if it were something completely different though, say, a Suzuki GT 380 triple…
Motorbike mad
Tim Wilson is a self-confessed petrolhead with a passion for anything two-wheeled.
His main obsession is with the Lambretta and over time he has created several stunning examples. A few years back Tim built one with a Yamaha YVPS engine conversion but still had a hunger inside to do something even greater. He wanted a new challenge – something that hadn’t been seen or done before. The answer came by way of attempting to use a different engine with the same outcome, this time using a Suzuki two-stroke triple instead. Produced in the 1970s, the engine kicked out 38bhp and, combined with a six-speed gearbox, could reach a top speed of just over 100mph.
Three into two doesn’t go
Tim decided this would be a perfect choice and as a keen fan of the Suzuki he already knew a lot about the way the engine worked. With a donor found, the next stage would be to make it all fit. One of the major problems is that the engine itself is rather big. Combined with the
Rather than have one pipe per cylinder Suzuki, in their quest to make things more impressive, decided to make the exhaust for the middle cylinder split into two. This means it exits on both sides and thus takes up more space.
larger gearbox and strange exhaust configuration, it wasn’t going to be an easy job. It seemed back in the early 1970s that bigger was better to make the Suzuki look more impressive. There seemed no point in making the engine compact and looking too small in the frame. Another problem that needed working around was the exhaust. Rather than have one pipe per cylinder Suzuki, in their quest to make things more impressive, decided to make the exhaust for the middle cylinder split into two. This means it exits on both sides and thus takes up more space.
You may be thinking, well at least it doesn’t need a radiator to cool the engine and so there will be more space available that way. That is correct but to cool the engine Suzuki came up with a ram air system which fed in from above the top. Take into account that all this needs to sit under the frame loop and you have serious fitment issues. Just when it seems there can’t be anything else there is the final issue of the leg shields. The motorcycle frame had no obstruction from the front so the air could feed in easily. With the Lambretta the leg shields are in the way, blocking the airflow. This gave Tim a lot to think about but, with an engineering background, a challenge he would relish.
Best of both worlds
To make it all fit Tim took the main cradle that holds the engine in the Suzuki frame and cut it out. This now had to be grafted on the Lambretta frame, which incidentally was a GP. Unlike when doing the YVPS conversion, more of the frame tube needed cutting away. This is because the engine with the exhausts is much longer – therefore to get the original
A few years back Tim built one with a Yamaha YVPS engine conversion but still had a hunger inside to do something even greater.
Lambretta wheelbase dimension it needed moving further forward. The actual cut was done just by the two front struts for the leg shields so a significant amount had to be taken out. Using a jig, Tim made sure the front and back sections were perfectly in line.
Now with half a frame from a Suzuki and half from a Lambretta, the next stage of getting it all to fit could commence. Due to the extra engine weight, it was necessary to add two support struts. They were anchored to the Lambretta frame tube just below the bottom of the fork stem and connected to the engine cradle. Tim worked out this would give the frame the rigidity it needed.
Sacrifices
Once a rolling chassis was completed, the task of the bodywork could be tackled. As already mentioned the engine is big and very wide to allow for three cylinders compared to two on the YVPS. This means fitting of the traditional footboards is impossible so they were simply left out. Also, the side panels would need to be much wider to go over the engine. Tim’s solution was to use the top shell and just the top half of each side panel. This didn’t look odd – after all, the star attraction is the engine and doing it this way shows it off perfectly. Cutting around the contour of the ram air system makes it look as if that’s how it would have been done in the factory, a clever idea.
With the leg shields, thought was required how to allow air through to cool the engine. Tim’s answer to this was to cut out a large oval area directly behind where the front mudguard sits. This meant from the front you wouldn’t notice this piece was removed because the mudguard hides the fact. The air could now flow freely underneath and directly to the engine. To give a slightly more enclosed look, a fairing was added underneath which enclosed the exhaust pipes as they curve underneath the frame. Venting grilles were added to aid with cooling.
To make a few finishing touches to the styling, the front leg shields were slightly narrowed and rounded off. It had worked well for Bertone, so why not for Tim. At the rear of the frame, the back light unit was done away with and a much smaller round one put in its place. This allowed the back of the frame to be narrowed slightly and tapered off in the process. It is styling like this that gives a professional and refined look to the whole thing.
And the rest
The front forks and wheel were taken from a Peugeot Speedfight, to which Tim added a disc and hydraulic caliper. The rear wheel required a sprocket to be made to compensate for the gearing due to using a smaller diameter wheel. This had previously been calculated when he did the YPVS conversion so it was simply replicated. The petrol tank was custom built and made as large as possible to fit in the space left behind the engine. It holds around nine litres and Tim reckons it has a range of around 60 miles. Because the tank sits quite high and, more importantly, above the carburettors it works on the gravity feed system. This does away with the need for a fuel pump, therefore making things less complicated.
Talking of which, the same can be said for the gauges. There is no need for a temp gauge for the water temp so the
option of an SIP multifunction speedo was chosen instead. A knock-on effect of all this is the wiring loom was pretty simple to make and didn’t require a mass of wires. Finally, the gear control is still operated by foot, like it was originally. This frees up the handlebars, allowing a hydraulic lever to be fitted on the right-hand side of the headset without too much complication as it doesn’t need to move to change gear.
Putting it bluntly, shoving a motorcycle engine into a Lambretta isn’t everyone’s cup of tea and to be honest, wasn’t mine. However, over time the idea has grown on me. Often the idea is distanced as it’s deemed the easy way out when it comes to getting a powerful and fast road-going scooter. Perhaps it is – but the flip side to this is that it throws up a whole host of engineering challenges to make the conversion successful. Also because of these challenges, the solutions required need a lot of thought and imagination.
The overall effect of this is that it creates a unique custom scooter that is full of ingenious ideas to make it all work. Tim has created something different simply by using an engine in a Lambretta that’s never been used before. We are all used to seeing the Yamaha YPVS conversion but this is one step further. The finishing touches put on by him really make it stand out and showcase his talents perfectly.
Suzuki also made a 750cc version of the GT series. I wonder if Tim has thought about this in case he has plans for another project in the future.
Words: Stu Owen
Photographs: Gary Chapman