My 1937 Brough Superior SS80
|1994: That's how the bike looks today. It certainly isn't in concourse condition, but I can use it without being afraid to put a little scratch in the paint.|
|It did look worse two years earlier, but it wasn't half as bad as it would appear from this picture.|
|After the first 1000 miles, I had a pretty nasty problem with the big
end. When rebuilding the engine, I had not split the crankshaft as the big
end had been renewed by a professional engineering firm, and the bike came
with an invoice proving this.
After it had seized up in a grand way (no there is nobody standing off
camera and holding the rod ends!) I dismantled it and found that the
crankpin had not been properly installed; the oil ways had not been lined
As the lower rod ends were badly overheated I chose not to re-use them. Instead I rebuilt the engine using a new Harley Sportster conrod and big end assembly. The Sportster crankpin ends have been reground to fit into the original flywheel bores.
|The MX80 engine has the crankcase breather situated between the two
lower ends of the barrels. Unfortunately this is a place where the flywheels
fling a lot of oil.
As the rear chain does not need so much oiling (and the rear tyre even less so!) I tried this little mod. It is a deflector that guides any oil coming with the drive side flywheel around the breather outlet without restricting the air flow.
My rear tyre is dry now and the chain does still get enough oil.
|A picture from the 1994 Alpine Rally of the BS Club. Riding up these
passes I found my 80 would keep pace quite well with the JAP 100's !
The bike to the left of mine is a 1932 JTOR 100 if my memory serves me right.
|2003:This is ATP about 10 years later. I don't use it a lot, but when I do, it is always giving me the reassuring feeling that I could go on a 1000 miles trip the next day without worrying.|
|9/2004:During the Brough Club's Umbria "do" I
noticed that there was a slight problem which seemed to be getting worse: On advanced
ignition and especially when the engine was hot there was a distinct pinking
sound when you opened the throttle. It seemed to come from the rear pot
only. Knowing that the compression ratio on my engine is slightly higher
than standard I suspected detonation, possibly provoked by heavy carbon
deposits. I decided to investigate as soon as I would be back home.
So I took the rear cylinder head off, expecting to see a bald spot on the piston crown due to the detonations. However, the piston crown looked perfect....
|... as did the inside of the head. (but note the hot running exhaust
valve. Charming as side valve engines are, I feel they all run too hot...)
A closer look revealed the problem: The arrow points at a defect of the (solid copper) cylinder head gasket. Some of the holes in the gasket were not very accurately drilled. On this one, the narrow land between the hole and the combustion chamber had given way, thus allowing the combustion gas under pressure to escape into the bolt hole. From there it must have blown through the minute gap in the lock washer under the bolt head, which treacherously sounded like a pinking engine!
I made and fitted a new gasket, and all was fine. No more "pinking", not even when ascending a hill on a hot day with full throttle and full advance!
For any kind of feedback my e-mail address is
(sorry, this is not a clickable 'mailto:' hyperlink. If you want to write me, please type my address in your mailer. )
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