Honda SL125 Big Bore Kit (Is it worth the effort?)

Barrel and piston need a fair bit of machining to get them to fit, but its possible.

[@bsa_brummie7775]

That was a surprise as well as interesting. You would have thought the supplier had already come across the challenges of fitting their kit numerous times and made the changes / upgrades to fit without it being necessary to carry out those modifications?. Hopefully there is enough meat / depth in the top of the piston to take the detonation. Engines specs do change surely they would be able to check the kit to match your 1971? motor, after all they are pretty standard. Well done for completing the modifications and sharing 👍

[@TheCADengineer]

Hi, difficult to measure but inverting the piston and tilting it to the parallel face of the inlet valve machined face on the drill press table there’s about 4.5mm of thickness using the vernier height gauge (so won’t be taking it to the drag strip running it on methanol) On the next video l will show where the kit came from, it says it’s for the CL, SL, XL and CB, however it misses the piston at TDC on compression stroke, but the cam profile must be radically different on the SL for the TDC overlap and induction cam curve. Regards Brian