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Anyone owned a British motorcycle in North America? Is it true they leaked oil?
every Brit marque I saw of the '50's-'60's and into the early '70's all leaked/seeped oil. their casting and machining techniques, materials, and finish work greatly improved as time went by, but not before they'd lost so much market share to other brands that they were out of business by the 1980's. For the most part, this series of bikes were essentially designs from the 1930's-40's with incremental improvements trickled out in the post-war era to generate a difference year by year ... (oh look! ... a bigger front brake this year, next year it's twin leading shoes up front, then a bigger rear brake, this year a bigger set of intake valves, next year higher compression, and so forth ... little incremental upgrades/features to make the next year's model "new and improved"). The Brits needed export dollars coming in post WWII and anything they could build/sell to capture that revenue that sold was a priority for them to build and ship out. They already had existing designs and tooling in hand that proved to be popular with the exposure to Americans during the war, so they were ready to build more of that stuff to ship out ASAP. Hence the popularity of the Brit roadsters and bikes of the era, but they didn't keep up with the developments from other countries (Asian, German, Italian, even Spanish bikes) as time went by.
it could be quite a project to get them to stay dry with the sealers that came out in the 1980's, but with due care to dressing up the mating surfaces and careful assembly, they could be made to stay pretty much dry.
of course, the new Brit bikes of recent years are built with contemporary updated designs, castings, and materials. Have to be to be competitive in today's marketplace where an oil leaker is not a sign of quality design/build.
My '71 Norton burnt more oil than it leaked. Vertically split crankcase seams didn't help.
this was likely a production bike from an era when the Norton factory went through Brit gov't mandated changes to facilitate some gov't welfare/employment programs. Norton had to move production into a different facility and train new production workers who had no background in such work, they came from a fishing village background.
one of the flaws of the scheme was that Norton had to maintain production volume at their own expense while training the new employees who came from very diverse backgrounds, not industrial production work.
one consistent flaw that showed up was that the people doing the machining of the cylinder heads did it improperly. They left a spiral groove in the valve guide bores in the heads that was deep enough to weep oil past the intake valve guides.
Berliner (the USA importer) was soon alerted to the problem of the oil burning Nortons of those production runs. But they didn't have enough margin in them to do a recall to have the heads remachined and oversize valve guides installed to seal this up. It wasn't a safety issue nor enough of a EPA pollution issue to warrant further attention. Many dealers weren't aware of the problem nor were a lot of the bike 1st owners, they just figured that the bikes were oil burners.
I had some success a few years later drying these bikes up by replacing the intake valve guides and sealing them in place with a high temp industrial epoxy. A quick knurling of the intake guides with a UTP threading knurler and reaming to a closer tolerance than factory for valve stem to guide clearance helped, too.
I rarely saw Norton crankcases seep at the crankcase halves. They were pretty well machined to a close fit at the factory. Timing cover, head gasket, ignition drive, or cylinder base gaskets were much more common seeps.
this was likely a production bike from an era when the Norton factory went through Brit gov't mandated changes to facilitate some gov't welfare/employment programs. Norton had to move production into a different facility and train new production workers who had no background in such work, they came from a fishing village background.
one of the flaws of the scheme was that Norton had to maintain production volume at their own expense while training the new employees who came from very diverse backgrounds, not industrial production work.
one consistent flaw that showed up was that the people doing the machining of the cylinder heads did it improperly. They left a spiral groove in the valve guide bores in the heads that was deep enough to weep oil past the intake valve guides.
Berliner (the USA importer) was soon alerted to the problem of the oil burning Nortons of those production runs. But they didn't have enough margin in them to do a recall to have the heads remachined and oversize valve guides installed to seal this up. It wasn't a safety issue nor enough of a EPA pollution issue to warrant further attention. Many dealers weren't aware of the problem nor were a lot of the bike 1st owners, they just figured that the bikes were oil burners.
I had some success a few years later drying these bikes up by replacing the intake valve guides and sealing them in place with a high temp industrial epoxy. A quick knurling of the intake guides with a UTP threading knurler and reaming to a closer tolerance than factory for valve stem to guide clearance helped, too.
I rarely saw Norton crankcases seep at the crankcase halves. They were pretty well machined to a close fit at the factory. Timing cover, head gasket, ignition drive, or cylinder base gaskets were much more common seeps.
The cylinder head seepage was mild and I covered that up by painting the fins black. I never did fix the valve guides since I sold the bike.
1978 Triumph Bonneville, 750 cc twin. Triumph briefly returned to the North American market, after Trident production ended in 1975. I would say it seeped a little oil, not enough to stain the garage floor though. Except for a flat spot off idle from the carbs tuned for emissions, it was a great riding motorcycle. Can't say anything newer is any more fun to ride.
Back in the 80s we used to joke that Harley fixed the oil leak problem and the first box of kotex was free.
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