R12s Exhaust valves!

mole2000 · Post by **mole2000** » Fri May 09, 2014 3:39 pm

Has anyone else had the exhaust valves heads part company with the stems?
My 06 12s disgraced itself while I was performing an overtake, 3rd gear approx 7000rpm. Loss of power, lots and lots of oil smoke out of exhaust, then relay home!!!
O/s head, barrel, piston, exhaust and inlet valves, exhaust valves for N/s as a precaution, new valve springs all round plus all gaskets.

Now back on road, but knee replacement forces me to look at it while I'm on the mend! Knee due to wear and tear, not motorcycle related!!!

nab 301 · Post by **nab 301** » Fri May 09, 2014 7:30 pm

Not personally , and I'm not sure if it affected anyone on here although someone (pb boxer ? ) had a major 12S blow up, but I think I remember reading of valve problems on some of the early variations of the 1200 albeit in the more common GS.

Blackal · Post by **Blackal** » Fri May 09, 2014 8:26 pm

It's always the RHS Cylinder apparently.........

Al

slparry · Post by **slparry** » Fri May 09, 2014 8:51 pm

Blackal wrote:It's always the RHS Cylinder apparently.........

Al

Yep the owner of one of the local tyre emporiums had his 12GS do similar.

I seem to recall the airheads went through a phase of the same, to the point that (I think) the valves on R45/65's were a 30,000 mile service item at one time. Something to do with a bad batch of friction welded valves

mole2000 · Post by **mole2000** » Sat May 10, 2014 8:16 am

Indeed, the question was asked at the local dealers re bikes from that era, the answer was "no not common, we had maybe 5 or 6 bikes in this branch!"

My local independant has done a couple of 12GS's that had same prob, they were both RHS too, and the distruction happened at lot lower RPM so not quite so much collateral damage.

Still something about the boxer engine keeps me coming back for more