Lambretta Imola 186 cylinder: Touring or Reso - you decide the setup
Bore 64 mm, stroke 58 mm, Nikasil-coated aluminum cylinder.Timing: Exhaust 178°, transfer port 125°, intake - diaphragm-controlled, advance 26.5°.
The layout of the Imola is strongly based on the TS1, so the diaphragm intake ensures good filling in the lower and middle rev range. The Imolas offer enough meat on the exhaust and overflow sealing surfaces for further tuning measures. With a high-revving exhaust such as the KRP2 or KRP4, speeds in excess of 120 km/h are possible.
If you like it a little more comfortable, you can change the characteristics of the cylinder by selecting the exhaust. With the bgm Big Box or Big Box Sport, the whole thing goes more in the direction of touring, which means that longer gear ratios can also be used. The whole thing then takes place at a moderate speed level.
Conclusion: Baby TS1,
BUT the timing should definitely be measured and you should be prepared for the fact that it may have to be adjusted. In addition, the combustion chamber volume of the head must be determined and possibly increased in order to build a reliable engine suitable for touring. Especially in combination with 60 mm instead of 58 mm stroke, the compression can increase to such an extent that it can lead to a major engine failure.
On the diagram you can see a nice band of the Imola engine with 60 mm bgm crankshaft, 30 mm bgm PWK carburetor and the Jl3 exhaust. The reference run (red) is an Indian Stage4 engine (Sh22, Indian big bore exhaust).
Do you have any questions about the diagram or the cylinder?
lambretta@scooter-center.com
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