|
|
Technical spec: T5 barrel machined out and fitted with a steel liner and Suzuki
piston ,skimmed head, standard crank and re-jetted standard carburettor.
Cost: £175 exchange - your standard barrel and head are required: or £200 (approx) outright.
This demonstrator was also fitted with a modified PM Tuning expansion chamber incorporating an automatic exhaust valve. Chamber also available from CJ Scooters for £155.95.
It's just three years now since Vespa brought their first sporting scooter for well over a decade to the UK. In that time it's established itself as the enthusiasts' choice, as its predominance at rallies would emphasise. I was lucky enough to have ridden one of the first batch brought into the country. I bought one almost immediately and if you're a regular reader of the magazine then you'll know that I haven't stopped going on about them since.
We're talking about the T5 and it's a subject on which, I have to say, I consider myself something of an authority. I tested the first 'real' expansion chamber made for it by Mikeck and thought it was so good that I actually paid for the Mk.2 version. I tried out the first machine to be fitted with a Pinasco 166cc kit and was completely underwhelmed by the experience.
Since then, most efforts at improving the performance of the high-revving motor have been concentrated at the extraction end - So when Clive Jones of CJ Scooters told me that he was testing a kit that went a long way to compensating for the 125's weaknesses - 'peaky' power that falls off dramatically two up, on hills, or into strong headwinds - I thought it only my duty to take it out and give it a sound thrashing, in a manner of speaking. Here's what I thought:-
The first thing I noticed was how firm and precise everything felt. I immediately suspected that the suspension had been uprated but a quick check later found everything as the factory had intended, which is, I guess, the difference between a machine that's brand new and one that's three years old. Still, it wasn't the handling characteristics that were under consideration. So, without further ado:
PERFORMANCE:
Acceleration: Just the day before I'd been down the road on a friend's Jap-pistoned TS1 225 that should have had a G force indicator instead of a speedo, so this felt quite restrained in comparison. Taking nothing away from it, though, it's considerably quicker than standard through the gears. It's smooth, too, with none of the `grabbing' or erraticness of a lot of tuned machines.
Top Speed: If you accept that the standard T5 will reach about 70mph, then this one must be knocking on the door of 80 mph. Afterwards I spoke to CJ who currently rides the demonstrator to work every day and has already clocked up over 1000 miles, including the round trip to Morecambe, and he agreed. The reason for all this guesswork being that the speedo was, literally, on a 'go-slow' - 60mph being the limit of its travel.
Pro's: Torque. A bottomless pit of it. Coming up fast on a roundabout, I braked hard, pitched the scoot in and accelerated out. All in fourth gear. Try that on a standard T5 and you'd not only stall it but probably fall off as well. This also means that it climbs the steepest incline effortlessly and an educated guess would be that two-up performance is just as impressive.
Con's: The clutch was a do-or-die affair that made lifting the front wheel a cinch and stalling just as easy. More importantly, because it is so biased towards, the bottom end it tends to run into a brick wall in each gear, with no further benefit to be gained from opening the throttle much more than half way.
Summary: The aim of this kit makes my comments very much redundant. It has been developed as a road-going conversion which can be bolted-on by the home mechanic. Reliability was considered equally, if not more, important than out-and-out performance. Unlocking the kit's potential with a bigger carb, lightened flywheel and uprated gearing could add an extra 10-15mph to the top end but could blow it to bits if you didn't know what you were doing.
This is the first stage in an ongoing development programme; the next stage is nearing completion and I for one will look forward to trying it out, hopefully for a little longer than I had with this one. Recommended, for the time being.
Editor's footnote: The more perceptive amongst you will have noticed that the demonstrator has `190' all over it. This was due to a misunderstanding between the people who painted it and those who did the engine, as well as a bit too much optimism on Clive's part regarding completion dates. The next stage in the development by Mark Broadhurst will be using a different con-rod to make the stroke longer and using a larger piston - a true 190cc, which should be available in the near future.