It is strange to think my last post before this was back in March 2020. That was just one week before the (first) UK Corona virus lockdown. My girl and I managed to get away for a camping holiday at the start of July. We went up to Scotland to see friends, camping in their garden as the Scottish lockdown rules then permitted. After that, we could stay at a freshly reopened camp site in Northumberland, near Hadrian's wall. It was very cold but absolutely wonderful to be able to get out again.
Ruby went well with the Daytona 1200 (red profile) cams and lower gearing but she was noticeably thirstier. Also, and more seriously, on the fast trip back down the M6 and M5, she disgraced herself by leaning engine oil over the rear tyre. Oh dear. Once again, she had overwhelmed the capacity of the engine breather to keep oil in whilst letting blowby gases out. Plus I could see oil escaping from the cam cover, the rubber seal not seeing properly.
The breather arrangement on the very first engine is via a catch chamber just behind the cylinder block. The so called"hatch engine". Most people who know these engines will be aware that there's an inspection cover under the carburettors. It lies over the starter gears and was also initially a breather chamber. It contains a wire mesh condensing element, intended to minimise oil transmission to the airbox. Gases enter the chamber in two ways: one past the starter gears, and the other bits a short link pipe from the clutch cover. A second breather pipe then links this chamber to the airbox for blowby gas recycling. I do wonder if the disappearing oil problem reported in there contemporary review by Fast Bikes was due to the inadequacies of this arrangement. In any case, there must have been issues with this system or cost savings to be made because the breather function of the chamber was deleted in 1992, in favour of a single pipe linking the clutch cover to the airbox.
I've had problems with oil expelled from the breather several times before, usually when riding extended periods at motorway speeds. The thing seemed to happen if running at or above 4000rpm for more than half an hour. I really wanted this early arrangement to work. I like the idea and a similar chamber above the gearbox was used on Kawasaki motorcycles. Sadly, I have not been able to do make it work reliably. So I have now blanked of the condensing chamber in favour of my own catch tank, currently a bottle cable tied to the left side of the engine.
We went out on another camping trip in Kent and Cornwall in September 2020, and this breather catch bottle arrangement was problem free, including several motorway hours riding from Whitstable to Bude. Just not tidy too look at. I'll find a better place to site it, now I know it works.
I also changed the cam cover seal and reinstalled the original, green cams. Ruby feels just great line this. At the mostly gentle speeds so far enjoyed on the lanes of England, in warm weather, she is returning about 47 miles to the Imperial gallon. Perfect.
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