L.A.B. said:
A 153xxx serial wouldn't even appear to be a legitimate 1971 number.
I was going by this web site. Sorry for the mis-info.
http://www.britishspares.com/42.php[/quote]
"Yes, according to the official numbers, 1971 production supposedly ended at 150500 although there seems to be a few 1971 Commandos around with 151xxx serial numbers."
I realise this thread is aging a little, but there are some serious misunderstandings being promoted here.
Here are some facts...
No. Modifications
128646 New type sleeve gear and layshaft pinion tooth form.
129897 Rear wheel security bolt and MK2 type frame.
130979 'APEX' oil control ring (3 bits not 5).
132576 Fiber clutch friction plates, (not cork postage stamps).
133488 3rd gears in stronger material.
134108 First engine built in Wolverhampton works. all engines with suffix 'P' built at Plumstead Matchless London factory.
134738 'Hylomar' (Rolls Royce) sealing compound
136618 Magneto blanking plate fitted
140061 Plastic rocker feed pipe.
141783 1st-'71 model-non-adjustable steering head hearings.
146584 New type "S.E." oil control ring.
147730 Rear brake drums screwed and riveted.
147846 Toughened kickstart pawl - stamped with m for lost wax
148895 Modified inlet valve guide (for oil seals).
149670 Oil seat fitted to inlet guide.
150120 Oil pump paper gasket fitted.
151175 Increased chamfer on cam followers to increase oil drain from head.
152000 Rear drum strengthening webs.
152499 Replaceable foot rest pegs.
153150 Riveted clutch back plate.
153124 Tachometer housing gasket.
153362 Chaincase outer incorporating cap 'O' rings, not leather washers.
200000 Revised shape handlebar levers (Tomaselli). 1) shape not flat.
200000 Commando (std) cylinder head with increased inlet guide support (deleting two NM23392 heat insulating washers). Oil feed return pipes 162200 commonised for spares (17in).
200708 Cam follower locating plate modified to accommodate 1972 combat camshaft.
200976 First Combat engine (interim pistons with oil slots).
201778 Clutch plate "scrolled" groove.
202116 Master switch replaces 39565 (now 4 terminal) with associated headlamp and main harness. Stops headlamp working when parked.
202341 Valve spring bottom seat washer thinned to accommodate cylinder head variations (tip to 202666), stops coil bound springs.
202666 Cylinder head amended to accommodate std NMT2073 heat insulating washers (ie reverted to 060966 (1971), canceling above mod engine 200000).
202760 Revised front brake lever (disc-master cylinder).
203136 Front drum brake support plate introduced.
203200 Steel petrol tank (Roadster) and side covers, not GRP.
203884 Copper sealing washers introduced under rocker spindle plate bolts, and not before time.
Now, what you may notice in there is that the various people that state that 150500 or 150723 were the last '71 are mistaken. You have to remember that a model year change doesn't just happen with the last old one, and then we change over to the new model. It's a change that could easily happen over three months, first with individual manufacturing proving/ test bikes coming down the line, then a break of a couple of weeks, then batches of launch bikes for the far-flung colonies. Back to building the current model year, then a batch of show bikes, then another break back to current model year. Another couple of weeks on the current model year, then dealer launch bikes. More current model year, then press bikes. Back to the current model year, and then finally when bulk stock is available from all suppliers, off we go with the new model year.
Trawling the various sources, 150723 was built in 10/71 and was the LAST SS, NOT the last 1971 model year (MY) bike. Reasonably, if the full change-over took three of four months, at a build rate of 1000 a month, it's quite reasonable to expect the last 71MY would have been built in January or February with 153723 or even 154723. My own bike supports this with a 153495.
As to the machining on the crankcase, my later Mk 5 is faced off and stamped with 230233. From what I can see, the typeface is identical. It also looks to be identical to 153495's gearbox stamping, although the '1' upstroke is difficult to see.
From the above, there is nothing to show your bike is anything other than straight. Beware the merchants of doom...
Furthermore, elsewhere in another thread on this site states that his "first Norton was a '72 combat roadster 201123 that was stamped as built Oct '71." My guess is that the factory started running with 200001 FASTBACK Mk. IV, ROADSTER Mk. IV probably all went quite smoothly, and they thought they'd be running out 71MY around 150500. 200976, the first Combat comes down the line - and we're only talking weeks, here. Suddenly all hell starts breaking loose, test bikes failing and they're firefighting like mad. So what would you do? You go back to building 15xxxx 71MY bikes. And 'cos everyone's running round with their hair on fire, unsurprisingly, factory records get confused, and either don't get written, or don't get updated... Anyone got a 154xxx?
