The Knowledge - Velocette Owners Club

this case the restriction of the inlet needle is acting as the main jet, that is, it is limiting the amount of
fuel going in to the carburetor air stream. And yes, weak 50 year old valve springs can cause valve
bounce. But 50 year old strong ones will not.
L #2002 If I leave my bike running on tickover ,it has periods of about five seconds (a long time
when you're wondering whether it's going to stall) of running at varying speeds. Adjusting the air screw
seems to have minimal effect. I'd guess that it's something to do with carburettion but exactly what I'm
not sure. Plug looks OK so don't think it's that. It's got to be something to do with the pilot feed because
at full whack it makes me feel like I was seventeen again (Ariel, I have to admit -But Hartley tuned)
#2004 Could be a worn slide taking a little time to settle into place and leaking a bit of air until it has.
#2075 Have you checked the face of the carburettor where it bolts to the manifold ? It is quite common
for this to bow (warp) if over tightened. If so either reface using a piece of glass and fine grinding paste
or fit a soft cork or similar gasket with a smear of silicon sealer to see if that effects a cure.
L #2047 I have spent an inordinate amount of time trying to prevent my newly rebuilt Viper basket
case from pinking once the engine was hot and under load at low revs (even when gently feathering the
throttle). Eventually after lots of experimenting with timing without real success( it is coil ignition so the
base plate of the contact breaker can be moved to advance or retard the ignition easily), a friend
suggested the mixture may be too weak ( needle position 2nd groove from top). I raised the needle to
the bottom groove to establish if any change and the problem was instantly cured. I have since fixed
the needle in one groove down from middle and the engine will only pink if severely provoked now. I
have never known an engine to be so sensitive to mixture strength under load before to result in the
degree of pinking I was experiencing.
L #2285 HI everybody on the list, Pete here, have recently joined the forum and have read
eagerly the discussions about all things velo. I myself have a Venom veeline clubman and have
recently ripped off the electronic system in order to go back to the original mag. However, even with the
assistance of friends, one of whom has had velos for many years, the correct timing is eluding us. I
understand the timing should be 38 degrees before top dead centre, although that is certainly how we
are setting the timing up, every time we go and start the bike the timing seems to be out, this has varied
from being 34 degrees before to being so far out the bike is just kicking back. So what is happening, it
could possibly be that the bike is on the wrong stroke. What I am not sure of is what happens if the bike
is on the wrong stroke, what are the symptoms? Although nothing seems to be moving with respect to
putting and tightening on the auto-advance retard unit, the timing remains out. I am now wondering
whether there is something so obvious that I can't see it. Have checked to make sure the timing disc is
not moving, the points are not moving during the instalment of the auto-advance retard unit, etc. Any
suggestions would be greatly appreciated, the bike is my main form of transport for work and therefore I
am keen to get it back on the road asap. In advance of any suggestions thanks, Living in the Essex
area if there is anybody nearby who might be able to help.
#2286 If the bike will start, you are obviously on the right stroke of the cycle, or the bike would not run,
nor would even fire. You do not state which magneto you are using, but do mention auto advance. I'm
sure you realize the timing spec, 38 degrees is full advanced, which requires the auto advance
mechanism's bob weights to be "locked" in the out or advanced state, when setting the timing. Rubber
blocks or small wood wedges work well for this.
L #2565 How slow a tickover can you achieve on a Clubman ? And do you tune it fully advanced,
or fully retarded, or in between ? My engine is in very good general condition, fitted with a newly rebuild
BTH mag (really excellent job done by Dave Lindsley) and a concentric (pilot jet 30). The best even
tickover I can achieve is in slowing down the carbs at full advance to about 1200 rpm, and then retard
ignition to slow to 1000rpm, about half way. Under 1000 it will run quietly for a while, and then stall,
usually as the traffic lights turn green, with 50 cars waiting in the lane behind, as you know. Do you
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