Author Topic: 55,000 miles on a 47 Vincent  (Read 126 times)

Offline worntorn

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55,000 miles on a 47 Vincent
« on: 15.12. 2018 02:57 »
I've caned this bike hard for much of the riding so it wasn't a big surprise when noticeable compression loss showed up about 5,000 miles ago.
Total mileage on the bike is somewhere around 400,000 miles according to club info. Of course it has had several major rebuilds in order to cover this mileage over seven decades.
Last major was 55,000 ago when I bought the bike in Australia.
The expectation was to do a top end rebuild this winter. That should see the engine thru to 100,000 at which point the bottom end will likely need renewing.
Although maybe not!
What I found at 55,000 was rather surprising. The valve stem wear measures just 2 ten thousandths, of an inch. Really just a nice polish in the guide areas.
The cylinders are perfect, no scoring and zero ridge at top. Will measure for wear and ovality tomorrow. I suspect they will be fine.
The rocker bearings ( duraluminium) show no visible play, so as new.
The valve guide clearances all measure well within normal spec, again very close to new numbers.
The compression loss was due to some pitting of the valve seats and crud on the exhaust seats. That all cleaned up with lapping compound, valves are gas tight again.
I bought some new valves thinking the 55,000 mile ones would be toast, but they are in great shape and back in.

I don't know if I will live long enough to ever wear this thing out!

Glen

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Re: 55,000 miles on a 47 Vincent
« Reply #1 on: 15.12. 2018 12:33 »
Flippin cheek, coming here, taunting us with tales of a real quality motorcycle! How very dare you!

Offline worntorn

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Re: 55,000 miles on a 47 Vincent
« Reply #2 on: 15.12. 2018 19:05 »
 *smile*It was meant to give hope to others.
Im sure there are also a7s and 10s that have also done good mileages without problem.
Both here and on the Norton site we seem to see a lot of serious mechanical issues at some very short mileages.  This might be due to less than stellar replacement part quality in some instances, I'm not sure.
Glen