SmedSpeed XS650


engine rebuilds

The XS650 is a veritable icon of motorcycle design. Very popular throughout its entire lifetime, it has recently entered a rebirth stage. The initial engine design was a typical 70's Japanese engine design, very strong, good materials, and most notably all roller bearing. After many years of British designs utilizing a mixture of shell and roller bottom ends, the designers at Yamaha opted for a complete roller bearing design, amongst other cutting edge (for the time) design features, basically a 2 stroke bottom end with a four stroke top end.  These engines were built to last.

However, well over thirty years since the last XS650 rolled off the production line, most engines are in 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 six years I have been building XS650 engines, I have built engines for street bikes, sidecar Moto-cross, sidecar road race and flat tracking, 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.

After much deliberation I have decided not to offer engine rebuilds as part of my core business from 1st January 2017 onwards. The focus of the business will now concentrate on supplying the sub assemblies required for owner driven rebuilds. This will include rephased and stock crank rebuilds, UK made performance cam shafts in both rephased and stock phasing, oil filter kits and carburettor and manifold kits.

I will be as usual 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.