Happy 10th anniversary bgm PRO RT Lambretta cylinder kits

(Probably) the best Lambretta Touring Kit

Unbelievable how time flies! Ten years ago, in 2013, we were able to ship the first mass-produced MBgm RaceTour cylinder kits for our beloved Lambretta scooters.

The project began in early 2012 as a joint venture between MB Developments and the Scooter Center. Mark Broadhurst had designed the kits and produced them in the UK for a while. Production in the UK was time consuming for Mark as many steps were required to see the finished kit and this made it very expensive.

The main differences between the British MB version and the bgm versions are*:

• Die cast cylinder
• CNC machined
• Ceramic coated
• CNC cylinder head with more cooling
• Standardized timing

*According to Mark Broadhurst's excellent mbtechsite.co.uk

Over a few beers, Mark and we decided to produce the RT 195 and 225 kits in larger quantities and with a special cylinder head. To cut a long story short: The RaceTour kits are considered by many to be the best Lambretta touring kit ever. It is a bulletproof design that offers an extremely reliable engine with excellent fuel consumption. So it's not without reason that even those with much more powerful scooters take their RT-equipped bikes out for touring or rallying.

TESTING THE PROTOTYPES AND IMPROVING THE SETUP

Here at SC we had eight pre-production kits to test, four 65mm and four 70mm. These were tested on various machines on the dyno and then used for proper road testing. There were slight differences in setup and we tested many head designs with different compression ratios, all hand-finished by Mark. What amazed us about the samples we had, and later in production, is the consistency of our cylinder manufacturer. Over the years we have assisted so many customers with setup tips and our packer/spacer ideas have always worked and delivered the desired squish gap.

FIRST RT 195 AND 225 MBgm RT SAMPLE

Here you can see the Excel sheet with some engine information:

DYNO WORK FROM 2011 AND 2012

Here are some test bench sheets created during the development and testing phase.

TOOLS AND INNER CORES

However, it was not without its problems. Mark, being a perfectionist, wasn't entirely happy with the tools; they were simply shipped around the world. Mark then spent 30 hours modifying the layout of the intake, transmission and exhaust ducts. Job done and ready to move on.

CNC-MANUFACTURED HEADS FROM GERMANY

Once the perfect compression ratio for good power delivery and built-in reliability of the RT kits was defined, it was time to manufacture specific cylinder heads. The first attempt with cast blanks from India failed miserably as they were unable to maintain the cast part due to porosity. A master plan was required and we looked at CNC machining the head. The CNC shop across the street came into play and was the solution.

ORDERLY PACKAGING RT Lambretta cylinders

The last point was the packaging of the kits. It had to be safe and also nice and tidy. An easy goal to achieve.

Funnily enough, the first proper production kits went to good friends of ours, Andy Gillard of (now) ScooterNova fame and Markus Wessner of Jockey's Pit Stop fame. The proof of history in our computer system looks like this:

RT225 Lambretta cylinder

RT195 Lambretta cylinder

Who would have thought at the time that eight years later Sticky would have THE COMPLETE SPANNER'S LAMBRETTA Kit Book in which he reviewed and bench tested all available Lambretta tuning kits and complete engines.

Here are some quotes from Sticky's Lambretta Kit Book about the MBgm kits:

To be honest, the RT kits had a weak point at the beginning. Initially they were fitted with a forged piston which caused some problems with the ring pins. On June 12, 2016, a Facebook group called Lambretta BGM RT195 Problems appeared.

The ring pin problem, which occurred on some but not all forged pistons, caused a lot of headaches in the UK and Germany. The solution was to change the supplier of the pistons. With the Italian company Meteorwe have the perfect source for literally indestructible pistons.

At the end of January 2017, we were finally supplied with our new pistons by Meteor, launched a recall of the old ones and exchanged the old ones for new ones free of charge. An offer that was valid until the end of 2017, and since our Italian friends supplied the pistons, we haven't seen a single piston fail again.

Neil, who started the problem Facebook group, renamed the group to Lambretta bgm RT195/225 User Group . By far the best and liveliest group for all technical questions about the bgm RT kits. At least the questions that our assembly instructions for the RT kits and the extended carburetor jets leave unanswered.

We say HAPPY BIRTHDAY RT Kit and look forward to many more smiles per mile!