Lambretta TS1 engine rebuild

These pages assume you have some mechanical knowledge & experience of working with Lambretta or two stroke engines. This guide has the engine mostly dismantled (the easy bit) & removed from the frame. The entire procedure can be accomplished with the engine in situ, it's just a little trickier.


Before proceeding follow these links to remove/replace the main bearings:

Time to complete approximately 2-4 hours.

Pucker Lambretta crank 1. This is the longer crank (110mm) I'm fitting. It has padded Indian crank webs, with a 22mm big end & Japanese conrod.  Fitting the crank9. Unlike in these shots, first fit the magneto side bearing track, ideally using heat & the correct tool (see Betta Tools) Next turn the con rod to bottom dead centre & insert through the crank case mouth.
3mm packing plate to raise cylinder height.2. With the longer crank that standard (110mm) a 3mm packing plate is required to raise the cylinder height.  Crank seated10. This picture shows the crank seated.
Close up Taffspeed modified TS1 exhaust port3. Here's a close up view of the exhaust port which Taffspeed have modified as part of their road/race tune. Crank tool 11. This workshop tool is used to ensure the crank is pulled through & aligned correctly. 
Dowelled cylinder head & TS1 barrel4. Finally the cylinder head & barrel were dowelled to ensure perfect alignment. This also means no head gasket is required. Drive side components12. Now its time to fit the drive side components including the sprocket. First fit the dished oil thrower over the crank.
Close up view of 3mm packing plate5. This picture shows the 3mm aluminium packing plate & the areas that need cleaning up around the transfer ports.  Oil thrower & drive side sprocket fitted13. You maybe lucky & there's enough slack in the chain to fit the spline & sprocket other the end of the crank. If not remove the clutch bell.
Cleaned up 3mm packing plate6. This picture shows the packing plate after some light filing. 14. Now fit the remaining components onto the crank spline. These absorb any "shock" transmitted from the gearbox/clutch to crank. 
Lubricating the big end bearing7. Before fitting lubricate the big end bearing with some two stroke oil.  Fit the clutch holding tool15. Fit the clutch holding tool in preparation for tightening the drive side bolt. Now loosely tighten the drive side bolt that holds everything together.
Grease up drive side oil seal8. If not done already apply some grease to the drive side oil seal & drive side crank face. Tighten this up as far as you can!16.  Ensure the parts move on the spline & are seated OK (tap lightly). Once happy tighten it right up using the correct size socket. If this is mechanism is not fitted correctly it will foul or crack the casing when this is fitted later!