SmedSpeed XS650


engine rebuilds


The XS650 is a veritable icon of motorcycle design.  The initial engine design was a typical 70's Japanese engine design, very strong with good materials. The engineers at Yamaha did a good job of “benchmarking” engines from the competition, and the engine is a relatively good internal copy of the Laverda 653/750 twins of the time, whilst the head is pure Triumph in appearance and the clutch cover similar in shape to a BSA A65.

However, well over thirty five years since the last XS650 rolled off the production line, most engines are in dire need of a rebuild. Whilst they still run, and to the inexperienced seem to run quite well, most have worn to a high degree, and as a result are down on power and up on engine noise and oil consumption.

In the nine years I have been building XS650 engines, I have built engines for street bikes, sidecar Moto-cross, sidecar road race, flat track and hill climbing, in fact almost every type of racing. I have learnt a lot about these engines, what makes them go and what makes them stay together even when you abuse them badly.

I will continue to supply the sub assemblies required for owner driven rebuilds. This will include rephased, stock and lightened crank rebuilds, UK made performance cam shafts in both rephased and stock phasing, oil filter kits and carburettor and manifold kits and much more.

I will as usual be more than happy to assist with engine build technical enquiries via e-mail or phone, and have put together detailed photographic instruction sheets for the assembly of all my products. I look forward to assisting you in the coming years......

Contact me for more details

These are experimental parts intended for racing and as such no warranty is given or implied. If you decide to buy it is on the understanding that you assume complete responsibility for any possible injury, loss or damage that may occur as a result of using these parts and that you accept these conditions of sale prior to purchase.