Scooter Boy Tales
When the Lambretta was upgraded to 200cc the power difference was noticeable. All that was now needed was a little tuning to increase it even further..
Another cracking Scooter Boy story from the annals of Scootering history
Having spent the first couple of years of my scootering career running around on an old Li 150, the inevitable upgrade was bound to happen sooner or later. It did, with the acquisition of an SX200 for a meagre £80. It wasn’t roadworthy, but having gained some knowledge of work on these Italian marvels, it soon would be. What a difference compared to the now obsolete 150 that had been discarded to the back of the shed. More speed, more acceleration, and at last a half-decent front disc brake that attempted to stop the thing when instructed.
Unfortunately, the initial excitement of the superior SX 200 quickly tailed off and it felt rather mundane. Of course, it was going to feel faster than the lesser powered machine I had earned my spurs with, but the reality was that it was only marginally quicker. There was only one option to get more power out of it, and that was by way of doing some tuning work. That, however, was easier said than done, having never attempted anything like this before. The first place to start was with the exhaust. AF Rayspeed advertised the Clubman, which sounded okay, but the 42mm reverse cone sounded even better, so that had to be the only choice, followed shortly by a 30mm Dellorto carburettor. With the emphasis on bigger is better, surely this must mean faster? All this ‘bolt-on power’ as it was advertised was fine, but the real power increase was to be had through porting, whatever that was.
By chance, I had acquired a couple of old motorcycle magazines from the 1960s which contained small articles describing exactly what I needed to do. It looked and sounded quite simple, and all that was needed was a drill and a rotary file. A quick trip down to the local hardware shop armed me with all that was required to carry out the procedure as described. The barrel was soon extracted from the engine and clamped tightly in the vice, ready for its operation. The magazine showed some old boy opening up the inlet and exhaust port on a cylinder, with about two sentences actually describing what he was actually doing. No problem, as I let the new sharp-edged file cut its way through the old Innocenti cylinder. Working on the ‘bigger is better’ theory, it wasn’t long before both ports had dramatically increased in size. Soon the cylinder was cleaned up and back in the engine ready to go out on its first speed trial.
Just looking at the SX 200, it visually oozed power, from the chrome VW tailpipe on the exhaust to the huge bellmouth on
Just looking at the SX 200 it visually oozed power, from the chrome VW tailpipe on the exhaust to the huge bellmouth on the Dellorto carb.
the Dellorto carburettor. More impressive was the sound when it fired up, as the exhaust note assaulted my eardrums. It was so piercing, virtually every dog in the neighbourhood was barking like mad, not mention setting off next door’s car alarm. Without hesitation, I shot off down the road and made my way to where there was a long straight, which was ideal to unleash the beast. The sound from the engine was exhilarating and a joy to behold, and with expectations high the throttle was fully opened up. Unfortunately, there was a slight problem as the expected surge of power didn't quite go as planned. It sounded great, like a big American V8 muscle car, but the acceleration was like a milk float at the end of its round with a flat battery. The only thing left to do was to limp back home and try to work out where it had all gone wrong.
The answer wasn't going to be that simple, no doubt because I didn't know what I was doing in the first place. Back down the local scooter shop to gather advice, I was sold the Dave Webster tuning manual with the instructions, ‘Read this before you do any tuning work’. I had heard of this Dave Webster bloke before. Apparently, he was becoming one of the leading scooter racers in the country. Surely he would know a thing or two about this tuning lark? Burying my head in the book, it soon became apparent that there was more to porting a barrel than I had ever anticipated. The manual went on to explain that some tuning attempts would be so way out that they would make the scooter slower than when it came out of the factory. That was me all over. It also explained why my left leg was soaked in petrol on that first outing after I had done my porting work.
Reading further, the manual explained the basics of port timings and different stages of tuning. Most annoyingly, it also said that once you have taken too much metal from the cylinder, you can’t put it back, thus making it scrap. It was back to the drawing board and another tenner gone on a second-hand barrel and piston. This time I was going to get it right. Rather than go gung-ho for the most power, it seemed best to follow what the book said, one stage at a time. Soon enough, with what can only be described as mild porting I was back out on the road. This time, however, it worked. Acceleration was far better than the first attempt. Over the next few weeks more work was done to the cylinder, and by the end a credible increase in performance was achieved. As for those magazines from the 1960s… well, the articles were entitled ‘Tuning for speed’, but they should've been ‘Tuning for slowness’. They did have their use though, as being ideal for stopping oil getting on the floor when draining the gearbox.