I'm looking at purchasing a R60/7 and would like to know if there are any known problems or things to look for when checking the bike.
Any tips most welcome.
The /7 series was a good one, I think as I have a '78 model. What year is the R60/7 you're considering? To me, the /7 series is only the 1977 and 1978 models. Some of the on-line fiche seem to consider the /7 out to around 1984. But the bikes were very different in 1981 and were a tad different over the 1979-1980 period.
Other than just the usual mechanical background (what's been worked on, what's been changed, oil used, spline lubrication, etc.) the only thing that I would be aware of is the tendency to ping for the R60 series from 1970 through the end. This was due to high compression pistons 9.2:1 and an agressive cam profile. They were trying to wring the best performance they could out of this smaller engine. The pinging can be helped with an electronic ignition that delays the advance curve (like the Boyer) and base gaskets can be installed to lower the CR. Plus keeping it tuned to within an inch of its life.
Should be a nice performer. The R80 was probably the best, being big enough and with the same bottom end as the R100. The R80's were known to be very smooth.
The /6 model came out with the 1974 models. Bikes built in late 1973 would be considered 1974 models.
I think my comments still apply to the /6. My Dad had a '75 R60/6 that we couldn't get rid of the pinging on. But that was before I knew much about these bikes. An electronic ignition probably would have fixed it.
With a bike at that many miles, you should enquire about how stable the valve clearances are and what they have been setting them to. Settings of 0.006 intake and 0.008 exhaust would be ideal. Eventually, these bikes will face valve seat recession due to the lack of leaded fuel. If the valve clearances close up quickly, say in 500-1000 miles, then it's time to consider a top end job to replace with unleaded components - probably valves, seats, and guides. Also, with this many miles, likely the pushrod tube seals need attention and you should probably measure the cylinder dimensions and ring gaps to see where you regarding the need the go to 1st over.
If you do get the bike and before any of the above is done, you should do a compression test or a leak down test to give you some idea of what to expect if you head towards a teardown.