BGM Race Tour ‘RT’ 225 upgrade – A tale of 3 engine casings: Part 1 | FEATURE

Just to set the scene, we’re riding to the Stax & Gas rally in the summer of 2019. I’m sat behind the missus, Linsey on her Series 2. I’m on my Quattrini-powered Eibar. She’s doing close to 70mph as we overtake an artic on the two-lane M42. Everything is good.

Then suddenly it’s not so good, her cast iron Stage 4 200 seizes solid as she’s drawing level to the cab of the lorry we’re overtaking. There’s literally nowhere for her to go. In the millisecond it takes to register what’s happening she pulls the clutch in and I ride up the outside of the coasting scooter between her and the central reservation. She’s signalling with her throttle hand to let the cars behind know there’s an emergency, whilst her left hand holds the clutch in. The lorry driver sees we’re having a problem and slows down instantly, then he guides her across to the hard shoulder and slows the rest of the traffic down. He was a hero that day.

That was the day that Linsey lost confidence in her engine, although we rebuilt it with a fresh cylinder and new piston and she used it again for Southport 2019. Fast forward to September 2021 and after almost two years of not riding it Linsey realises Weston-Super-Mare is coming up, it’s a 360-mile round trip via the motorway. We decided it was time to upgrade her engine.

The plan was to have it built, run in and on the dyno before Weston. We didn’t figure in the on-going problems with the postal service between Germany and England though so the Weston deadline was out of the equation and the parts arrived two weeks before Southport.

Rob Miller starts to remove the engine as wingman, Tim looks on. Little did they know that this straightforward job would take the best part of four days!

Tuesday – day one

Linsey’s Series 2 was on the bench just before lunch and we removed the engine ready for Rob to start stripping things down. Once stripped, his righthand man, Tim cleaned everything down and things were looking good. Or they were until he noticed that a bit of the alloy around the bottom of one of the cylinder studs was missing, after removing the studs it was clear we also had a crack running down into the bore from two studs.

Enter casings number 2 (left on image), a spare set I’d bought a few years ago and never needed… until now.

Luckily I had a set of spare Spanish 200 casings at home so I nipped back to fetch them whilst Rob took the gearbox out of the original engine. I’d bought the bare casings as a spare set a few years ago and they’d just been sat there so they needed a bit of attention before they could be used. Rob cleaned them up (they’d had a repair on the inside of the drive side seal), made good the threads, did a couple of thread repairs and it was time to knock off for the day. A fairly simple engine build had fallen foul to the Gods of Lambretta (or the metal fatigue and ritual abuse of a 60-year-old engine).

Things were going well so far on day two…

Wednesday

Arriving back at Simply Retro for round two we were hoping for a better day. The replacement casings were all ready for Rob to build. What could possibly go wrong?

Starting with the rear hub bearing and 5-speed gearbox seemed like a good idea, so Rob fitted those and spent quite a bit of time shimming it up (end plate on and off a few times). All new sidecasing studs were fitted. Then came the driveside bearing followed by the new 60mm crank, mag housing and piston. The RT kit comes with a set of fatter cylinder studs so they were wound in. All the threads in the casing were good after Rob ran a tap down them. Next it was time to slide the cylinder on… only it wouldn’t slide down the studs. After a bit of head scratching we swapped two of the RT kit studs for the smaller diameter BGM ones and the barrel slid home, albeit still quite tight. This was our first indication that these casings may not be as shiny as their chrome-effect powder coating suggests.

From bare old casings it takes a good few hours to get to this stage, especially after re-tapping threads etc.

Once it was all tightened down Rob did a squish check and it was a bit high, so a thinner base gasket was used. All good. Time for a quick leak down test and we’d be riding it home by teatime…

From bad to worse!

Riding home for teatime!! Or not as the case may be.

It failed the test badly and after searching around for a bit we found the culprit was the alloy welded repair around the bearing. It was leaking like a sieve.This was very bad news. It was spewing air through a hole that was invisible to the naked eye. We also think the previous repair work had warped the casings altering the stud positions slightly, hence the BGM studs not fitting as they should.

Check out the video below, moments after the video ends three grown men are consoling each other as we realise we’ve wasted one and a half days and have to start all over again tomorrow.

If you’ve ever messed around with these vintage shopping bikes you’ll know that you have to expect the unexpected, a simple job is quite often more complicated than it should be and if you have a budget prepare to smash it.

Enter casings number 3: A new set of Uni casings requisitioned from an unsuspecting friend, thanks Daz