From: D.J. Walker
Date: Thu, 27 Jul 1995 16:32:03 +0100
Dear All, Just an insignificant thing. Many Commando parts suppliers
now insist you describe double-S cams for the Combat as "2S", if you wish
to abreviate, rather than "SS". This is because if you ask for "SS" cams,
they'll as like as not give you the camshaft for a Domminator 650 Sports
Special (SS, see?), and not a Combat. Argueing that you'd told them it
was for a COmmando won't help either - the
650's cam fits all the 1960s Commandos.
Thus, they will have provided you with exactly what you asked for, and would be perfectly entitled to refuse you any refund.
I mentioned this point to Steve, who posed the cam question. Please don't lynch me for being so lit'ral-minded!
Dan
P.S. Steve, the data on 2S cam profiles wasn't to be found in the source I thought it was in, but I'm still a-working on it.
From: D.J. Walker
Date: Fri, 28 Jul 1995 17:05:09 +0100 (BST)
Dear All, In response to this problem of identifying the Combat's 2S cams, I rang Les Emery about this just now, and he says the old 2S cam*should* bear the stamp "S S" on the left hand end lobe area. This is a little confusing, since I wrote earlier saying that a 2S cam should never be described as an "SS", since an SS is the 650SS Dominator cam.... etc. But there's the manufacturer, gone and stamped "S S" on the damn things!
The cams from bikes in the low 200,000's (engine numbers) had plain ends and scrolled bearing bushes, as opposed to scrolled end and plain bearings, which is the normal setup. He agreed that the latter system is the better of the two, because it simply provides better lubrication. The 2S cams his company now manufactures all have this arrangement (as do all his other camshafts, of course).
His opinion of the 2S camshaft is rather low, and he reckons it's the least useful of the lot, as far as usable performance goes, whilst tending to put greater strain on the valve mechanism. The inlet cams of the S, 2S, 4S and 7S have each got successively greater lift than each other, running in that order. Someone has already said that the S has .332 lift, the 2S has .380, and as a matter of interest, the 7S, high performance cam has .470 lift. The 2S doesn't give enough power for its increased problem-potential, apparently. Why not see about a 4S, if you're thinking of changing it, or going to the gentler S-setup?
I mentioned to him that the Combat in question still had the old main bearings setup, and he said this showed the bike must have been run at high revs for much of its life. At a consistent engine speed of over 4000rpm the old setup is fine, Les told me, but if the bike is chugged around at 2-3000rpm, the bearing''ll give way. Either way, snapping of the crankshaft is more likely with the old setup, if you realy thrash it. I guess everyone knew this anyway, but it's nice to hear it from one of the experts.
Sorry I couldn't be of any better help, Steve. Anyway, I'm off for the weekend.
Commando Dan
10.2 Setting The Camchain Tension.
From: Peter Azlan
Date: Wed, 11 May 94 14:26:44 BST
It's not that I enjoy the frustration of engine maintenance, I just feel you need to be in the right mood, or to be more precise, the right frame of mind.
There are times when nothing goes right, there is always that one bolt or screw that just won't budge, but you persist, then things really take a turn for the worst. In your heart, you feel you just need to 'fix this bit', or 'undo that screw' and it will all start going right, but it never happens, not on that occasion anyhow.
There is probably some deep karmic reason for this, maybe its the phase of the moon, maybe its your biorhythms, the tides or what you've been eating. The thing is, the bikes working together with this force, and what you really should learn to do is give up when this happens, but of course you don't, and things go from bad to worse.
Setting the Cam Chain Tension on the Commando.
According to the manuals, this task should be tackled every 5K miles.
The notes that follow refer to a Mk 2, or pre electric start Commando,
Mk 3 Timing covers have a little inspection cover that looks like it's
for checking the tension without all of the following. You can probably
fit a Mk 3 cover to earlier engines, and get the built in anti-drain valve,
but it costs about 70 quid and you start to worry about originality, and
whether the bike is going to be the same bike you bought twenty five years
ago.
The first thing you start to ask yourself is, why use a chain, wouldn't it be better to use an intermediate gear like the Triumph twin Edward Turner designed?
Anyhow, how I did it the first time:
1. Remove the side panel covering the oil tank and drain the oil.
2. Undo the magnetic sump plug and drain the sump.
3. Remove the Primary Chaincase timing degree inspection cover and
turn the engine to 30 Deg, mark the rotor, there are two marks remember,
(TCD and BDC). [This is because you will be marking other 'stuff' for re-assembly
and the engine will probably turn while working on it]
4. Remove the gear indicator and lever.
5. Unscrew the points cover.
6. Mark the points back-plate and timing cover to aid re-assembly.
7. Undo the two pillar bolts and remove the points set complete. I
cut the wires to the points, couldn't see how I could remove the timing
cover and work on it otherwise. [I know the manual says you can pull the
wire through, but it was simpler for me this way, I have a soldering iron.]
8. Mark the position of the auto advance on the inside of the case,
again to aid re-assembly.
9. Remove the long bolt from the centre of the auto advance.
10. Put the bolt back an inch or so and tap the end a couple of times
from above to break the taper and free the auto advance, light taps are
all that's required.
11. Remove the banjo bolt that feeds oil to the rockers.
12. Undo all the screws retaining the timing cover. [The timing cover
is located with two dowels so no side blows with a rubber mallet will move
it, and may actually damage it]
13. From the other side of the engine, tap the oil pressure relief
valve and that bit of the timing case at the front that protrudes, (is
proud of), the crankcases away from the engine. This is to break the old
gasket and free the timing cover.
14. Realise you should have put something down to catch the oil from
the timing case.
Once inside, you are now able to check the tension on the Cam Chain.
There's a small gear on the end of the crankshaft, timing side, which drives a larger gear immediately above called, 'the intermediate gear'. This is used to achieve a 50% reduction in speed and change in direction. The intermediate gear has a sprocket attached which drives a chain which then drives a sprocket on the end of the Camshaft and thereby the Camshaft. There's a slipper tensioner on the lower, or return run of the chain. This is to reduce backlash in the camshaft and improve the lifespan of the auto advance.
In Bacon's book on restoring Norton Twins he goes on and on about how you can't set the cam chain tension with the cover off as there is nothing to support the intermediate gear shaft, the question is, If you haven't got a scrap timing cover, with holes cut in it for this purpose, (and very few people have) How are you going to set free play ?
The correct free play is, 3/16" slack on the top run of the chain, check in several positions, when correct, torque the adjuster nuts to 15Flb.
My camchain was so slack the top run had started eating into the top adjuster nut. On closer inspection, I found the rubber face of the adjuster lose at the bottom of the timing chest, the chain was also eating into the steel face of the adjuster.
Now the bad news, assuming you have to replace the slipper tensioner: This won't come off with the chain in place. Yeah I know the manual kinda looks like it does but I couldn't manage it. It does move about a bit, in a tantalising sort of way, but it really wont come off without removing or displacing the camchain. To remove or displace the chain, you have to remove either the sprocket on the end of the intermediate gear, or, the sprocket on the end of the camshaft, or both.
Although there is some side to side movement, the sprocket on the intermediate gear, and the intermediate gear itself, cannot be slipped off the intermediate shaft as the gear hits the spiral, or worm drive for the oil pump. If you chose to remove the intermediate gear remember, the oil pump worm gear has a LEFT HAND THRED.
The sprocket on the end of the camshaft is retained with a nut and located with a wodruff key. If you decide to remove this sprocket you will first have to remove the nut. When you do remove the camshaft sprocket nut, APPLY ONLY CONSTANT PRESSURE. Don't bash the spanner with a hammer to try and 'shock' the nut free, as this may tear the intermediate gear shaft out of the crankcase. You will need a good fitting socket or spanner for this, I have noticed that most sockets have a radiused opening which doesn't allow the socket to fully engage on the nut, allowing it to slip off all too easy. Once the nut is removed, the sprocket can only be removed with a small two leg gear or sprocket puller.
A note of caution, if you decide to pull the camshaft sprocket first this will pull the chain and intermediate gear out a little where the intermediate gear will start to interfere with the worm drive for the oil pump on the end of the crankshaft. If you then attempt to remove the worm drive, and this is usually a very tight fit, the interfering gears will start to cross mesh and destroy each other.
Thing is, if you do pull the camshaft sprocket, you can get the tensioner out without touching the worm or oil pump, just remember the to stop the worm and the intermediate gears cross meshing and eating each other.
Apparently there are two different types of slipper tensioner. The earlier one is plain steel, the later one is steel but with a rubber face. To me the later one is more attractive, I'd rather have bits of rubber floating around the engine than bits of steel.
While the timing cover is off you may chose to replace the oil seals located therein. The oil seal for the points can be prised out with a screwdriver, I drifted in a new one with a socket of the right size, this goes spring towards the engine. Don't forget to spread a little gasket goo on the outside of the seal to prevent oil escaping round the outside. Later points oil seals are red in colour, and are considered better quality.
The oil seal for the end of the crankshaft is retained with a circlip. Once the circlip is removed, you can prise the oil seal out with a screwdriver. This seal goes in with the spring, or gaiter, the other way round, pointing away from the engine. Again, I drifted mine in with a socket of the right size and a small hammer. The socket needs to be large enough so it bears down on the outer edge of the seal, but small enough so it clears the hole in the casting. When the new seal is in, don't forget the circlip, which should be fitted 'sharp' edge away from the seal.
It is recommended that the little rubber seal on the end of the oil pump, is replaced every time the cover is removed and replaced. This seal is responsible for maintaining oil pressure to the crankshaft, and thereby the engine, it only costs about 50 pee, (Uk) so why not replace it every time ? There's a lot of talk about this seal in the manuals, it needs to be a good tight fit. On some engines this was achieved with shims or washers fitted under the seal, in later engines a gasket was fitted behind the oil pump. Just lookout for the shims/washers and put them back if fitted.
When I replaced the camshaft sprocket and nut I torqued the nut down to 70Flb, there was no figure given in the manual but this seems reasonable. I never did get the worm gear with its left hand thread off. I wasn't able to lock the engine well enough by putting it in gear and applying the back break, I guess this is a job to be tackled when the engines out and I can replace the camchain at that time too. Removing the camshaft sprocket gives enough access to remove and replace the slipper tensioner.
One other thing, before you replace the timing cover remove any remnants of the old points seal from the end of the crankshaft where it protrudes through into the timing cover. A little ring of rubber collects there. And don't forget the service tool which protects the points oil seal when re-fitting the cover.
Once re-assembled, I have found two documented ways of providing initial lubrication to the engine and priming the oil pump, (you need to prime the pump if there is no oil in it). The first, and possibly simplest, is to remove the intake rocker cover, and fill it with oil. It looks like this then drains down the oil return and into the timing chest, not sure if this primes the pump though. The second involves priming the crankshaft with oil via the rocket feed banjo and pipe with about a 'tea cup' (yes, that what it says in the manual), full of oil through an oil syringe, I'll let you know how I get on.
HOW I WOULD DO IT AGAIN NOW I HAVE DONE IT ONCE:
1. Run the engine to clear the sump of oil.
2. Remove the Primary Chaincase timing degree inspection cover move
the engine to 30 degrees and mark the rotor.
3. Remove the points cover.
4. Mark position and remove the contact breaker base plate.
5. Mark position and remove the auto advance.
6. Remove the gear position indicator and lever.
7. Remove the oil feed banjo to the rockers.
8. Remove the 12 screws that hold to timing cover and remove the cover.
When the cover is off, oil will seep from the drilling in the crankcases, blank this off. Also plug the end of the crankshaft to stop all oil from draining.
9. Set cam chain tension, should be 3/16".
10. Re-tighten the tensioner nuts to 15Flb.
11. Fit a new cover gasket and cement.
12. Fit the points oil seal guide.
13. Remove oil feed blanking and crankshaft plug
14. Replace the timing cover.
15. Replace gear lever and pointer.
16. Replace auto advance, and points.
17. Set points gap and ignition timing.
Regards Peter Aslan, aka Captain Norton.
From: Terry Drehmel
Date: Wed, 11 May 94 09:24:08 CDT
Captain,
Excellent article. Outstanding! Though I do not own Nortons (and they
are gradually joining Boyer in my list of "Hmmm... could be trouble...")
I could see the procedure in my imagination with great ease. This article
will definitely be included in the B.S.'E. Workshop manual, easily better
written than my Haynes manual in some of the more common sections.
With this in mind, as Lord and Warden of the Grease Monkeys I present you with the "Louden Quill" for How-to that is Can do. Keep up the good work and the excellent writing, these articles help neophyte wrenches like no manual can because there is a human behind the writing and not an Editor.
From: John Pinkham
Date: Mon, 6 Jun 94 14:31:06 EDT
A few weeks ago, Colonel (then Captain) Norton shared the pleasures of adjusting the cam chain tension on his Norton with us. He said that he was unable to remove the oil pump drive worm because he could not lock the engine up enough to turn the securing nut (left hand Whitworth, of course). Well, Commodore, there is a way. Read it in the instructions for the automatic cam chain tensioner, I recently invested $80 US in. Here's how: Remove one sparkplug. Bring that piston to halfway up. Pour in engine oil until the volume is full. Replace sparkplug. Quickly remove worm nut, remembering that it's left hand thread. The hydraulic lock will gradually dissipate by leakage past the rings. Syphon if you are in a hurry.
Wonder if an air impact wrench might work also
Private Norton
10.3 Cam Chain Tensioners, the Third Way
From: Michael Taglieri
Date: Fri, 13 May 94 02:13:04 EDT
Apparently there are two different types of slipper tensioner. The earlier one is plain steel, the later one is steel but with a rubber face. To me the later one is more attractive, I'd rather have bits of rubber floating around the engine that bits of steel.
I believe the purpose of the rubber-covered slipper was mostly to reduce noise rather than protect the engine from steel particles -- Norton had trouble with EPA and English noise standards during this engine's last years. My '72 still has the steel slipper, but I've been afraid to get the rubber one because of the very problem mentioned here: the rubber can fall off and cause a dramatic loss of tension in the chain, especially since the metal underneath is not hardened. One guy in Classic Mechanics some years ago brazed a narrow brass track to the steel shoe so the chain rollers would roll over the shoe rather than the sideplates sliding on it.
There's also a third kind: a company called RMA Engineering (408/578-4032) advertises in Norton News (magazine of the US Norton Owners Assoc) an automatic cam-chain adjuster that replaces the slipper with a spring-loaded molybdenum disulphide-filled nylon shoe and costs about $70.00 -- you never touch it again after you put it in. I did a camchain adjustment last about 6,000 miles ago, and I'm grateful to Peter Aslan for reminding me what a hellish mess it can be. Maybe that'll get me to finally buy this contraption, so next time can be my last. USNOA is a great club, by the way -- the magazine alone is worth the dues. (412/376-4266).
2 other points:
1. If you don't have the service tool to protect the points-seal, you can get by with a smooth socket, 14mm socket or so. Push it gently into the points-seal, and it will fall out as the cover goes on, protecting the seal from the sharp edge of the cam.
2. Once you go to the trouble of getting all this stuff off to reach the slipper, it's not much more work to remove and rehab the oil pump to eliminate endplay on the gears. I'm not really sure why the oil pump would have to be primed if all you were doing was adjusting the slipper, but after a rebuild you can pre-prime it by filling it with Vaseline. This moves out quickly when you start, and once it melts and dissipates, it never solidifies again.
From: Peter Azlan
Date: Tue, 7 Jun 94 08:16:00 BST
This mail is really to Private Norton, (John Pinkham). Who tells us all of the existance of an automatic cam chain tensioner for the Commando.
Having aroused my curiosity, just how does one work, are they suitable for the good old Mk2, or just the Mk3 Commando, and where can I get one from ?
On the Isolastics, there are different Shims for the Front and rear, remember to adjust them off the center stand, and I always use something like a crowbar to force the engine to one side to allow a measurement to be taken.
As the Shims are different sizes, I suspect the Vernea (Sp) stuff is different front and back also.
When adjusting, the manual says 10 thou, the Blighty Police always set theirs to 6 thou, and the best advice is, as tight as possible (<10 thou) ensuring the vibration is bareable, and that there is some movement in the mounts, otherwise frame damage, (broken welds) will result. A real improvement in handling can be achieved with the Norvil Head Steady and mk3 type fixing the swinging arm (fork) spindle with more nuts and bolts.
Regards Captain Norton.
From: Michael Taglieri
Date: Fri, 10 Jun 94 01:17:36 EDT
I've noticed that several writers keep asking where to buy the automatic cam chain tensioner they've heard about for the Commando [or maybe it's the same guy over and over?], so I'm repeating the piece I wrote on this unit around May 15th, for their/his convenience. Everyone else, please ignore.
There is "a third kind" of camchain tensioner besides the metal and rubber-covered slippers: "a company called RMA Engineering (408/578-4032) advertises in Norton News (magazine of the US Norton Owners Assoc) an automatic cam-chain adjuster that replaces the slipper with a spring-loaded molybdenum disulphide-filled nylon shoe and costs about $70.00 -- you never touch it again after you put it in. I did a camchain adjustment last about 6,000 miles ago, and I'm grateful to Peter Aslan for reminding me what a hellish mess it can be. Maybe that'll get me to finally buy this contraption, so next time can be my last. USNOA is a great club, by the way -- the magazine alone is worth the dues. (412/376-4266)."
Since then, I've looked in more recent issues of Norton News, and see that the unit is now $79.95 ($5 more/Canada; $10 more / England). Recent ads say, "maintenance free, dampens cam chain vibration; holds valve and ignition timing precisely; proven performance in over 12,000 test miles." I figured anyone who wanted this would call first, but some of you overseas folk may not want to, so the address is: RMA Engineering / 447 Santa Mesa Drive / San Jose, Ca 95123.
Again I must stress that I have no connection with these people and do not own this device, although it's gotten good reviews and I may someday buy one.
{P.S. Thank you all for calming my fears about Raul's fiberglass tank; it sits very near to organs vital to human happiness, and I'm glad it's solidly made].
Michael Taglieri
Raul -- '72 Commando Interstate
From: John Bria
Date: Fri, 10 Jun 94 8:40:29 PDT
There is "a third kind" of camchain tensioner besides the metal and rubber-covered slippers: "a company called RMA Engineering (408/578-4032) advertises in Norton News (magazine of the US Norton Owners Assoc) an automatic cam-chain adjuster that replaces the slipper with a spring-loaded molybdenum disulphide-filled nylon shoe and costs about $70.00 -- you never touch it again after you put it in. I did a camchain adjustment last about 6,000 miles ago, and I'm grateful to Peter Aslan for reminding me what a hellish mess it can be.
From: Michael Taglieri
Date: Fri, 10 Jun 94 15:03:58 EDT
I've had one on my MK2A for about 10K miles (won it at a NCNOC Christmas party) and have had no problems, no adjustments ... kinda don't know it's there except for the decreased maintenance.
From: John Pinkham
Date: Fri, 10 Jun 94 16:04:58 EDT
Just to add a bit to previous posts by John and Mike to the subject: The cost of the automatic cam chain tensioner is $79.95 US including shipping and handling (might need a bit more to ship it to Blighty). The address is RMA Engineering,447 Santa Mesa Drive, San Jose, California, 95123. Tele: (408) 578-4032. Lady answers with crying baby in background. It comes with *good* instructions, 6 pages of 'em, well illustrated. The device consists of a mounting bracket which hold a spring loaded wedge. Keyed to the wedge is the nylon shoe, impregnated with solid lubricant. Only metal removal is said to be the lower dowel pin boss ( use a, pardon the expression, bastard file for this). Have new oil pump seals, etc. On hand before commencing the project.
Go for it!
Date: Thu, 4 Jan 1996 13:50:02 -0500 (EST)
From: Mike Taglieri
To all my knowledge a replacement is not only possible but also strongly recommended. your bewilderment ( metal on metal ) is very justified!
I've been using the standard tensioner for years. It's only the edges of the plates that rub on it, and do so when it's not under tension. I have virtually no chain adjustments for thousands of miles. Can someone tell me whether it is actually the consensus that this thing ought to be replaced?
Mike Taglieri
Raul -- '72 Commando Interstate
Date: Thu, 4 Jan 1996 13:50:02 -0500 (EST)
From: Colin Bryant
Mike,
I've been using the standard tensioner too (I have an early '69 so
there isn't much choice since the bonded face type only seem to be available
for the later single timing chain motor). I rode the bike for 90,000 miles
before replacing it with a good used one because the rollers were getting
too close. I have no idea how much over that 90,000 it had been in the
motor. It's quite possable that it was the origonal and therefore had about
190,000 miles on it. Obviousley I wouldn't bother.
Colin Bryant
From: Klaus Kaak
Date: Thu, 4 Jan 1996 13:50:02 -0500 (EST)
Hi colin,
I didn't know that there was anything other than a single timing chain.
Howlong did norton use a double rowed cam chain? my reply referred to single
chains & I believe that the bonded tensioner will give best service
here.thanks for illuminating me!
klaus
Excess on occassion is exhilirating. It prevents moderation from acquiring the deadening effect of habit.
In times when nothing stood, But worsened, Or grew strange, There was one constant good: My Norton didn't change!
KK and TP
From: Peter Azlan
Date: Thu, 4 Jan 1996 14:51:02 -0500 (EST)
Klaus, I think the Double Timing chain referred to here is a little confusing. The timing chain driving the Camshaft has always been a single row. The double chain which is being referred to relates to the second chain in the timing chest used to drive the distributer, in Early Commando or Magneto, in prior to Commando engines.
From: Dannysore
Date: Thu, 4 Jan 1996 14:59:02 -0500 (EST)
My '72 still has the steel slipper, but I've been afraid to get the rubber one because of the very problem mentioned here: the rubber can fall off and cause a dramatic loss of tension in the chain, especially since the metal underneath is not hardened. One guy in Classic Mechanics some years ago brazed a narrow brass track to the steel shoe so the chain rollers would roll over the shoe rather than the sideplates sliding on it. There's also a third kind: a company called RMA Engineering (408/578-4032) advertises in Norton News (magazine of the US Norton Owners Assoc) an automatic cam-chain adjuster that replaces the slipper with a spring-loaded molybdenum disulphide-filled nylon shoe and costs about $70.00 -- you never touch it again after you put it in.
I thought all those slipper things worked by having the chain rollers
roll/slide over them, it being expected that the chain plates would immediately
wear grooves in slipper. At least that's the way I remember the primary
in the Vincent worked.
Dannysore