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Shadow running but rough.


New Forum Website User
Non-VOC Member
My dormant shadow was revived this morning after a the addition of new fluids and the priming of the oilways. The bike started and ran after the third kick, although the rear exhaust was heavily blued after a short spin around the block. The carbs have been bored true and new 3 1/2 slides machined to match by amalsleeve in the U.S. the fuel tank has been sealed and all components cleaned and re-cleaned. Points ,plugs and valves have been adjusted. I am new to the world of the Vincent and although I am somewhat mechanically inclined, I am looking to those of you with the experience of many years wrenching vincents to provide some opinion as to the possible problem. The carbs have been adjusted to the initial specs included in the handbook. The rear carb seems to pulsate air in and out of the velocity stack while the front does not as well the rear does not like to come off the air slide as readily as the front. Any help greatly appreciated.


Well Known and Active Forum Website User
VOC Member
Make contact with your local Section, there is a wealth of experience there. Thirty years ago, you could find them at the Jolly Miller pub. Does it exist anymore?


Well Known and Active Forum Website User
VOC Member
Much of the information in the old books such as Richardson is out of date. For instance the figures for tyre pressures do not apply to modern tyres. Ignition timing is now recommended closer to 34º than 38º (even less for some bikes). Remember timing is done on No. 1 cylinder (rear pot). Blue pipe means lean (I think) so, depending on what throttle settings you were using I would raise the needle or instal a larger jet. Always only change one setting at a time or you don't know which change actually worked. It is not uncommon to have different size main jets on front and rear.
Good luck.


Well Known and Active Forum Website User
VOC Member
As Albervin says, not everything in the books is totally relevant now. If it hasn't been run on the new "petrol" you may need to richen the carbs.

If it was running right before you did work on the bike, I usually find that it's down to the Nut - the one holding the spanner. :)

I'd look for air leaks on the back carb, tight tappets, and carb synchronisation, before you get involved with anything major.

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