Lambretta Series 2 engine swap – Part 1 | FEATURE
After a hard couple of years on the road, Linsey’s Lambretta Series 2 is ready for some TLC. It’s been ridden to Ibiza and back this summer, as well as Belgium a couple of weeks ago, plus to most of the UK rallies.
The relatively standard (stage 4 top end/25mm carb/BGM exhaust) 200 engine was built by Malc Anderson at MSC three years ago and has covered a fair few miles with nothing more than a new clutch and the usual oil changes and routine maintenance. It’s been having a few issues this summer though, like a snapped inlet stud on the barrel (welded and still usable), a couple of minor heat seizures and the odd temper tantrum so it’s being shelved (the engine will be rebuilt over winter as a spare). Meanwhile, I bought a complete 200 engine last winter for £650, with the original intention of putting it into my Eibar, that plan changed when I opted for a Quattrini M210.
Spare engine rebuild
In spring we rebuilt the engine using new bearings and seals throughout. The engine had been reconditioned by the previous owner so many parts were new but it had sat on a shelf for about eight years, so I wanted to change the seals to Viton and make sure everything was ok.
MB stage 4
We were pleased to find it already had an AF Rayspeed crank and MB chain tensioner fitted but the top end was a bog standard 200. I bought an MB tuned stage 4 cast iron top end for it (second hand £100). This was just at the time when the new AF Clo5e 5-speed gearbox came out. With the help of our tame RS Racing mechanic, Alister we fitted the new gearbox and stepped rear hub bearing as well. Literally, the day we finished rebuilding the motor AF warned about selector failures on the new gearboxes, so rather than risk sending the missus out on something that could potentially fail, (leaving me with a huge lump sum from the resulting life insurance policy…) I opted to leave things as they were with the engine sitting on a bench for a few months. Meanwhile, Alister had also fitted a Clo5e gearbox to his scooter and is still riding it with the original selector fitted with no problems so far.
Eventually, the redesigned AF replacement selector was released in August and the gearbox duly stripped last month, the old selector sent back and the new one fitted.
The new Clo5e selector explained
Ben from AF Rayspeed told us about the design and manufacture of the replacement selector, and why it’s different to the proposed design we showed you here.
The tooling they use cuts the selector centre clean through the whole part. That means that the length of the claws (the part locating in to the dog of the gear) has to be cut all the way through. That prevented us being able to fill in the area we had wished to, without making the ‘claws’ unacceptably short. The main changes to the design are: the metallurgy is different (a measure of fatigue resistance) and it has a smaller critical radius size. It has had two rads put on to the location we had seen the cracks propagating from in the selectors that failed, and the ring diameter is larger than before (hence the requirement for us to supply extra gear pawls). The new design has been rather expensive and only 200 have been manufactured, essentially to replace the originals with a safe alternative as quickly as was prudent.
Road and race tested
Steve Wright has been running the new design in his group 6 race bike, with Scott and another local rider running them in RBs since June. The design improvement and testing gave us the confidence to get the replacement out to customers.
After surviving the Ibiza trip and the recent 600-mile round trip to Belgium, albeit with a couple of issues along the way, we decided to drop the engine two weeks ago (earlier than the planned winter swap over) and fit the new one. It’s the first time I’ve had the engine out of this scooter so it also gave us a chance to get rid of 57 years of accumulated filth on the frame once the engine was out.
You can flick through the gallery below for an idea on what’s involved with dropping a Lambretta engine if you’ve never done one yourself.
Dropping a Lambretta engine
I still have a fear of fitting bearings, it’s not my fault really but as a young 18-year-old I had a new red T5, complete with the failed drive side bearing the early ones were known for. My dad helped me strip and rebuild it. When fitting the bearing (using his biggest hammer) he accidentally knocked a perfectly circular section of the casing out, complete with the new bearing in situ. He bodged it afterwards using Araldite and a rubber mount for the flywheel, it lasted another few years and was still like it when I part exchanged the scooter for another T5 (my dad should have been a scooterboy, his bodging was mega). Since that episode, I avoid fitting them if at all possible.
The heat is on
When fitting (or removing) a bearing, the polar opposite elements of heat and cold are your friends, a cold bearing (left in a freezer overnight) and a clean casing thoroughly warmed by heat gun until your spit sizzles on the alloy are the best way to fit a bearing. If the casing is warm enough your bearing will literally drop into position as you can see in the video above. Be sure to heat the casing all around the bearing, rather than concentrating on one area. Also be aware that any residue oil/solvents in your casing could catch fire so make sure it’s clean and dry before starting.
Before we refit the engine there are a few other jobs we want to do so we’ll catch up with those in part 2. We need to get the scooter running, get some running in miles done and make sure it’s ready for Bridlington at the end of October.
New products always in development…