Our Pinasco 251 series has been running for longer than Forrest Gump but in reality it only took us three days to strip the old donor P2 engine and build the new 251 back in September last year. Three days of building, fettling, videoing and taking photos for this series.
Once Sticky had finally finished building the engine (how hard can it be?) I was able to take the newborn black lump home and put the finishing touches to it before fitting it into my street racer PX frame.
You can catch up, or recap on the first seven parts of the series here…
Flywheel cover
Those finishing touches included making an extension piece for the flywheel cover to allow it to meet the T5 head cowling (luckily we have a SLUK Plastics man on hand). If you’re building a 251 you’ll find you’re left with around an inch gap between the two.
Our solution meant we shaped a piece of plastic to mimic the flywheel cover, then fixed it using self tappers and panel clips on both the flywheel cover and cowling. SIP sell a dedicated wider cowling for the 251 so that’s another option.
Fast flow
We also fitted a KR Automation fast-flow fuel tap and performed a flow test. It lived up to its ‘fast flow’ name with an impressive flow rate of well over 1-litre per minute.
During the build, we decided to run the scooter without a fuel pump. Sticky runs his own 251 without a pump but has only used it for local riding and running around… that proved to be a mistake.
Note: During the build you should at least fit a feed for a vacuum pump. It’s easier than doing it later once you realise you need one.
Back in the frame
After sorting these few bits out the engine was soon in the frame (after doing a one-man balancing act whilst lining the engine bolt up). The electrics were also sorted, thanks to a colour-coded friend popping in to see me at just the right time. The Pinasco CDI and regulator replace the original Piaggio ones and it’s just a matter of piggy-backing a couple of wires to make it all work.
Video: She runs & dyno
I also fitted the Pinasco Touring box exhaust, put the rear wheel on and cabled the scooter up. With fresh petrol and oil in the tank it was time for the moment of truth – would it run? I’d like to keep you in suspense at this stage but it kicked into life after just three kicks. I’d also like to tell you it sounded lovely but the flywheel cover was catching the flywheel so the engine was quickly switched off and the cover bent slightly away on one of the louvres.
Shake down test
Ordinarily, right now, I’d do what any man in a garage with a freshly built engine does: chuck a helmet on and jump on the hastily bolted-together scooter in whatever garage scruffs/non-protective clothing you’re wearing at the time. Sadly, I’d misplaced the nuts for my rear suspension and engine bolt, so I’d have to wait.
Diablo Moto
Talking of workshop scruffs. Luckily that wait didn’t take long because I was booked in at Diablo Moto the following day to have things checked over, the timing strobed and for the carb to be set up on Al’s dyno. The good thing about taking a scooter to Al for setting up is that he’s a road and rally rider himself so he sets scooters up to be safe for hard rally use, rather than them being left on a knife-edge to eek the last bit of power out of them.
What’s on the graph?
Al explains it in more detail in the video but the engine is making 24.1bhp and 18.8 ft-lbs of torque, peak power is made at around 53mph so there’s loads of power for fast overtakes. Interestingly, in fourth gear the engine is still making just under 24bhp at 70mph.
Running in
I’ve never been a big fan of running engines in but I got this on the road at the end of September last year, at the same time as Linsey was running her freshly built RT 225 in. This reigned me in a bit as I did some steady riding with her in October.
I’d done a hundred or so miles before heading off to Southport for the last rally of the year and had a steady ride there with a group of other scooters. I didn’t even get a chance to open it up on the way there, but I was very impressed at how easily it rode with other scooters of mixed capacities. With a light clutch, easy gearbox and well-mannered nature, it felt just like riding a well-put-together standard P2, or T5 as the case may be. I got to Southport not feeling overly excited but pleased it had run without any issues. It was also surprisingly good on fuel.
Fuel starvation
On the ride back, I got caught at a set of traffic lights and was left on my own, so it gave me a chance to cane it. The wheelie off the line reminded me that this is a 24-horsepower motor! All was going well until the scooter felt like it had run out of fuel. It made me feel a little cautious for the rest of the ride home but I made it back with another 300 miles on the clock.
Winter was written off for me due to a back operation but I was able to get the scooter out again at the end of February to go to the Burton Brewers Custom Show. I opened it up a bit during this ride and I must say it put a big daft grin on my face. No problems on this 80-mile trip at all. A few days later I nipped out for a ride locally and ran out of fuel, or at least the scooter couldn’t suck any fuel as it got to the bottom quarter of the tank. I needed a fuel pump before the first rally at Easter.
Fuel pump
I made a trip back down to Al to have the fuel pump plumbed in, I’ll not repeat what he was calling Sticky for not putting a pump feed in during the engine build!
For neatness, I reused the CNC pump bracket from my previous PX engine. They’re available from Dave at Scooter Trumps and give you the perfect place to fix a pump on top of the crankcase.
Good Friday
It’s Easter Friday, and it was time for a 250-mile round trip to Whitby. I must say, this is the ride where I realised just how good the Pinasco 251 is for touring. Our group of 20 scooters consisted of everything from an RT 225 to TS1s, GTS’, Rapidos and an SST 265.
This engine will beat a GTS 300 from zero to 80+ mph. It’ll also annihilate anything else we were riding with (although the SST rider was taking it easy).
Fuel economy
Whilst the TS1s were battling against a headwind and guzzling fuel by the tank full, my PX just sat there on part throttle, sipping super unleaded through a straw. It had loads of power in reserve; open it up in fourth and you can overtake at will. It’ll climb decent hills in fourth as well. The 24.1bhp at around 53mph is well worth having, plenty of torque and the scooter is so easy to ride as well.
I really enjoyed the ride there and back. When we put it on the dyno, Al said I’d be able to stick it into fourth and ride it like an auto, and he was bang on.
I mentioned fuel before, during this round trip, I used just over 25-litres of super unleaded at a total cost of £43. In comparison, one of the TS1s was costing over £20 at EACH fill-up over the same distance. My average fuel stop was less than 4 litres and cost £6.73. I can’t grumble at that.
What does it cost to build?
Nothing fun is ever cheap or without compromises. The Pinasco 251 follows that philosophy as well! The engine is available in both rotary induction (Master) and reed valve (Slave) versions. VE (UK) currently offer the Master version for £2650 (Prices correct in 2022 when this article was written) as a 6-piece kit.
The kit includes:
- Crankcase
- Cylinder kit
- Crankshaft
- Bull clutch
- Flytech ignition
- Touring exhaust
What else do you need to buy?
You can buy it without the exhaust for £2484 or without the exhaust and ignition for £2190, which gives you the option to go for an expansion pipe and different ignition if you prefer. Remember that you still need a lot of other parts (including reed valve & carb), particularly if you aren’t using a donor PX engine. Without a donor motor, you can expect to spend another £1400 to build a complete 251.
To sum it up…
It’s still early days for this engine but you can be assured it won’t have an easy life with me!
I came back from Whitby absolutely loving it, it does everything I need in a touring engine. I could have gone for more power with a Quattrini M244/BFA 306 etc. but for a rideable long-distance Vespa, you don’t need mahoosive horsepower. This engine is for long-distance use rather than 1/8 mile sprints and small penis bar conversations. However, I would still like to try an expansion pipe at some stage where I’d expect to see around 30bhp. Using the Pinasco box exhaust, 24bhp and oodles of torque is a good enough figure though. It’s not revving its nuts off and it doesn’t feel like you’re riding an all-or-nothing race engine.
PX on steroids
As Al says in the video, “It’s like riding a standard PX on steroids with some other pharmaceuticals thrown in for good measure”. And that’s the thing I really like about this engine, it’s just so easy to ride at any speed. If you want to sit at 70 on the motorway you can, still with power left over to roll on the throttle and overtake. You can thrash it around the twisties and have a bit of fun but without it tying the chassis in knots or being too much for the brakes and suspension to cope with.
Thanks to its decent fuel economy I’m still able to use the standard fuel tank and get a decent range (60 miles easily when riding with others) which is a big plus point with the price of fuel.
Negatives?
For the average home builder, this engine isn’t as simple as building a standard PX engine. There are a few flaws, like the air leaks we found and the clutch basket not having enough space for the plates to decompress, also the ‘251’ timing mark being wrong on the stator and the CDI bracket needing to be adapted. We overcame these problems but there’s no reason why the 251 engine should come with any issues at all. It means the engine won’t be as popular as it deserves to be because a higher level of skill/ingenuity is needed to build it properly.
Our advice is that unless you’re a competent mechanic who is willing to put in the extra work needed to build, seal and set up this engine then you should take it to a shop that knows what they’re doing. Somebody like Diablo Moto or Readspeed if you’re in the UK. Both have experience building the Pinasco 251.
BFA 306
Of course, there are plenty of other Vespa tuning options available, many of them making lots more power than the Pinasco 251, for instance, the 55bhp BFA 306 (pictured above) can be bought from SIP for £4050 (inc VAT).
Engine cases SIP BFA 225 or 306
Cylinder kit SIP BFA 225 or 306 including cylinder head
Full circle crankshaft SIP BFA 225 or 306
Inlet manifold SIP BFA with 4 petal reed
Clutch SIP BFA conventional, 225 or splined 306 in various versions
Bearing set
Set of oilseals
Rubber bushes including spacer shims
Modified kickstart gear
Vacuum connection and blanking plug
Flywheel cover/cylinder cowling
Malossi alternative
If you want to compare pricing, here’s what it costs for the basic six parts to build a Malossi MHR 225.
- V-One crankcases (reed-valve) £675
- MHR 225 Cylinder kit with head £380
- Malossi 60mm full-circle crank £430
- Power Up clutch £126
- Vespower ignition kit £399
- MHR Racing exhaust £379
Total = £2389*
*Prices correct in 2022 when this article was written.
All that’s left now is for me to carry on using it as my rally scooter whenever possible and to see how well it lasts with some hard abuse.
Text, images & video: Iggy
