AV002 ADVERTISING/VALUING

I am about to look at a 1950 MAC. It has been off the road for a year and maybe not ridden much for some time before. Has anybody got any tips on what I should look for? This is my first serious look at a Velo. Born again biker after 30 years. - Graham Byett, 18/8/2000

Check the frame and engine and registration numbers match the current logbook, or you are in for lengthy discussions with the DVLC. (Check whether the registration number is the original or if not it might now be a 'non-transferable' one.)
Check for originality using the books in the website's 'booklist' section, or the catalogue pictures in the 'photo gallery' section. (Except the nearest year is 1949, so expect some differences)
External condition - paint and chrome - you can clearly judge for yourself.
The main thing is it should still start OK!
A 1950 MAC would have a magneto, and in general they seem to benefit from a long quiet period - unless they've been in the damp in which case the earth brush and points may need 'green stuff' cleaning off.
Lots of flooding, then a new clean plug and it should start. If not, either establish why or there is no way to know what you are getting into.
Lots of blue smoke on starting is OK, but it should be completely gone within 5 mins.
There should be no 'knocks' loud enough to be recognizable as a knock, but there will be 'ball bearing in a tin can' rattle on start-up, which is OK if it reduces steadily, which indicates piston slap which is always there when cold. If still prominent and/or still blue smoke after a test ride has got the engine hot, the engine top-end will have to be overhauled. If there is a clear knock or rumble when hot, then the bottom-end needs attention. Neither is cheap nowadays, but at least a top-end is straightforward.
You may have Dowty or Velo front forks. Dowty are unusual and need special checks, but wear in a Velo front fork's bushes or  corrosion of the tubes is tricky but recoverable, as is the same (in a 'springer') in the trunnion (pivot) shaft of the rear swinging arm and its bushes. Either will cause an MOT failure so check them the way they will be checked in the MOT - bike on its stand and/or a block to get both wheels in the air, pull the front wheel spindle back and forth and any clear 'play' back and forth (as opposed to flexing) which is not just a loose steering head would probably cause a failure. In a post '53 'springer' (i.e. with rear suspension - which should not be the case with a pre-'52 MAC) try to pull the rear wheel left and right and 5mm or more of clear movement of the wheel spindle indicates problematic wear.
A number of frames have been bent at some time in a Velo's long life. Surprising, because it is a pretty strong frame, until you realise the quite high chance of an accident at some time in 40 or more years use. A test-ride may show up a tendency to veer left or right, or crab around corners. Then check wheel alignment and if the wheels appear to line up reasonably well the frame needs to be investigated. Straightening a badly bent Velo frame is not a simple exercise.
These are the big things to worry about. Things like electrics, suspension units in post '52, clutches and so on are generally repairable or replaceable nowadays, but the above faults can take a lot of time and cash to sort out.
The main thing is whether you just want a Velo to ride, or to get to know intimately and restore it. For riding, search for and pay for a fully restored one which test-rides perfectly. Or identify the faults and allow plenty of your time to remove them - and you'll spend as much in total but you'll have much more satisfaction when you eventually ride it.
I'm sure there are lots more 'checkpoints' that others can contribute - TW 18/8/2000

Any comments on these aspects of a Velocette Viper that I tested:
1. The bike started promptly (the air temp would have been around 15 degree C) so it was cold by Oz standards but not UK. I set off and the motor ran nicely and the choke lever could be pulled back without affecting (in any obvious way) engine running. After around a km I approached a steep hill. The bike slowed on the hill (obviously) and on changing down I could not seem to get the engine to spin when I opened the throttle, eventually the bike stalled. I wondered at the time whether it was the slope affecting the carburettor. I just turned it down the hill and bump-started it easily. Later with the engine much warmer I tackled the same hill this time in a lower gear initially and with more revs and went up readily. So was the problem a characteristic cold start issue and it was it just a question of getting the bike warm?
2. The engine appears to run fine and revved freely once warm and has no obvious knocks (recognisable say as little end or big end), BUT just after start-up and the first kilometre or so, it did have a clear knocking sound. As I kept riding I stopped noticing it - is this the "ball-bearing in a tin can sound" related to piston slap that you refer to?
3. There is a plate under the barrel around 6mm thick. This plate also appears (when I look closely) in photos of other Vipers . Is this typical? My first reaction was that it might have been a spacer to lower the compression for some reason.
4. You do get definite vibrations through the footpegs in particular - I just take this to be typical of a single of this vintage.
Any feedback would be welcome. - DR, Australia 12/9/2000

My thoughts on your points are:
1. If you set off within less than a minute or two from cold, and took off all the choke then a "stagger" on a hill would be quite reasonable. But changing down should recover the situation if you are sensitive with the throttle - and maybe you just aren't used to a big single. By itself I wouldn't worry about this.
2. Sounds just like piston slap, and your Viper may well have an alloy barrel rather than cast iron, which accentuates the "ping" from slap and it has to be very hot before it goes completely on an alloy barrel. Perhaps for interest test it with a fridge magnet - if it doesn't stick on it's alloy. Again you would notice it more if you weren't used to 60's singles. If it doesn't smoke (at all) once warm, it's OK
3. The plate is right - it's called a cylinder base ring and it's spigotted into the crankcase mouth to take up the gap from using the same crankcase for both the 500 and the 350.
4. There shouldn't be much vibration, and you should only notice a slight tingle through the footrests at high revs (ie above 4,000) The usual reason for any other vibration is outside the engine - loose or broken head-steady, or loose engine plate bolts, or a loose component somewhere on the bike (loose mudguard stays can vibrate through the whole bike). Velos are pretty smooth.
There's no real way of knowing if the inside of the engine or gearbox is like new or at the end of its life, unless there are recent and obviously genuine records of what's been done by what shop.
Don't expect any old bike to be perfect, expect to have to do regular maintenance, expect at least one of the 40 year old bits to break each year and expect to take a thousand miles before you get the hang of riding (and starting) it. And allow extra braking time! It then becomes an extremely satisfying experience. 

See the end of saga EV005 for a summary of what, in my experience, will usually be needed to get the average second-hand purchase 'right'. Or rather the equivalent amount of work, it won't always be in these areas, of course. - TW 12/9/2000