Part 1: Catching up on SLUK projects – Lambretta RT 225 | FEATURE

As we get close to the start of the main scooter rally season I’m sure many of you are busy tinkering with your scooters.

We thought it was a good time to have a quick recap on some of our previous projects to see how the engines are doing.

Previous projects

Over the last few years, we’ve been running a Quattrini M210 in my Spanish Eibar. We also built a Pinasco 251 for my Vespa PX and for my missus (Linsey) we built an RT 225. These are three of our main rally scooters (although I quite often use my Lambretta Series 1 as well). All three of these builds were covered extensively on SLUK, you can look back at those features by clicking the links above.

BGM Race Tour 225

The first one we’ll take a look at is Linsey’s Race Tour 225. This engine was built at Simply Retro in Nottinghamshire by Rob Miller in September 2021. If you read (or can remember) those features you’ll find that things didn’t go smoothly, thanks to some knackered engine casings. We ended up building it three times and opted for a set of brand-new Uni casings on the final build. Those new casings made life so much easier.

Engine spec

Aside from the RT 225 top end, we also used:

• 60mm x 110mm BGM Pro Competition crank
• BGM Superstrong six-plate clutch
• BGM Clubman Sport Pro exhaust
• 30mm YSN carb with BGM elbow and filter
• BGM 19-tooth front sprocket
• Casa Performance X44 chain guide and stretched 82-tooth chain

Linsey’s original stage 4 200 engine already used an AF Rayspeed 5-speed Clo5e gearbox. The gearbox has been in there since 2018 and has been trouble-free so we reused it.

Since getting this on the road at the end of September 2021 this has been Linsey’s only scooter and she’s ridden it to almost every event she’s been to. I rode it back from the Belgium Euro in 2022 after the exhaust on my Quattrini jettisoned itself on a foreign motorway. I also rode it two up to Southport and back in October.

Faultless

Since being built there’s been no need to open the engine up. It’s covered just short of 2,000 miles so far. Other than re-torquing the cylinder head nuts and checking around it before each event there has been nothing to do. Of course, I also check and clean the plug and change the engine oil. The engine has been absolutely faultless. As a matter of precaution, we’ll stick a new set of rings in at the end of this year. 

Confidence boost

The main thing about the RT225 is that it’s given Linsey confidence in her engine again after a crash course in scooter seizures. That alone makes it well worth spending some cash on a reliable set-up. She absolutely loves it. 

Big tank?

This scooter still runs a standard fuel tank and it’ll quite easily do 60 miles or more before hitting reserve, we have pushed it to a tad over 70 as well. We usually ride with a group to rallies though so most fill-ups are at around 50 miles and it’ll generally take around 4.5 litres (the TS1s we ride with gulp way too much fuel). The RT225 is certainly not a thirsty engine. 

Other than a few miles of running in, I’d not actually ridden this scooter ‘properly’ until Belgium last year. My scooter had to be sent back in a van and Linsey was quite happy to ride pillion.

For one 70-mile stretch, I was riding with a clubmate who was solo on his own RT225. Our RT had way more torque and a much higher top speed than his scooter. So much so that after we got back from the rally he had a 5-speed gearbox fitted and sent it down to Al at Diablo Moto to be set up properly. He’s much happier with the scooter now. 

Top speed

I really enjoyed riding the scooter back from Euro Lambretta. It’s not a fast engine in the grand scheme of things but then it’s not meant to be. Mark Broadhurst developed this as a ‘Race Tour’ rather than ‘Race’ engine but it’s lovely and smooth. It pulls well, solo or two up and isn’t expensive to run.

Even though it’s not a revvy engine I’ve still seen 80mph on the SIP speedo (it’s very accurate as well) and it’s easy to sit at 60mph and just burble along.

Would I change anything? 

To be honest, I don’t think I would. It’s an easy motor to live with and does exactly what it says on the tin. I think the whole package works together perfectly and the 5-speed gearbox helps to keep the revs down. I find the gearbox is well worth having, although a couple of friends have been underwhelmed with theirs. One has had his swapped back to a 4-speed. Personally, I think people are expecting too much from them. The closer ratios and extra cog won’t supercharge your scooter but they will help to keep it in the power. Think of fifth as more of an overdrive for use on motorways but with the option to drop into 4^th if you need to without the engine screaming like it would in third. Using the standard 35-tooth gear gives a 9% rise to the gearing. The optional 34-tooth will raise that to 12%. For the type of riding Linsey does, the standard 34-tooth option is perfect.

If I were to build an RT 225 for one of my own scooters I’d probably opt for the reed valve version (Scooter Center are currently developing a new version) though and an expansion pipe of some kind. Just to make it a bit more fruity and give some extra power. 

I’d certainly recommend this engine for most rally-going Lambretta riders.

Words and photos: Iggy