Norton Commando Resuscitation Recommendations?

Discussion in 'Old's Cool' started by HapHazard, May 11, 2013.

  1. Quickduc

    Quickduc n00b

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    Let me preface this with some background info.


    My experience with Nortons ended in the mid 80's, pretty much. So, there will be new products/services I'm not up to speed on. Bare that in mind.

    However, I was a bike mechanic during the Commando years. Worked at a shop that carried European bikes, mostly, and we worked on anything that rolled. Started in '71. Owned a couple of Nortons. Bought a '71 that I had uncrated and prepped for the original owner. (he sold it when it backfired and caught fire. Fortunately, right in front of the fire dept. :d

    I quit riding after a stroke. Been about fourteen years now.

    On to my suggestions for your Norton:


    For the ignition setup: The points system can work well with some simple mods.

    First, make sure you have good return springs on the advance weights.

    Second, toss the original coils. Buy a pair of automotive coils for a V8 from the points era. There were optional high-output versions from some makers. "Standard" brand had a good one that had a gold tone body that looked good. If you ever tried the OEM coils on a spark tester, you would see how pitiful they are, which is why the specified plug gap is so narrow. Usually, new coils came with a clamp mount, and you should be able to use it to mount these in the same area as the old ones, however, they are larger, so make sure they aren't rubbing on the tank. BTW, you could mount these coils anywhere on the bike, as long leads won't effect the output to speak of.

    Third, toss the OEM condensers, and buy the matching ones for the coils you bought. This is very important! The reason the original points get eaten by metal transfer is the coils don't match the condensers properly. With this new setup, you will eventually wear away the rubbing block of the points, but the points will still look fresh. Just keep an eye on the point gap, and re-adjust occasionally. The OEM points rubbing block materiel is not up to automotive standards, I suspect.

    Fourth, you can now open the plug gap up to the automotive points era spec of .035", or so ( 0.90mm). Easier starting, and running.

    More later...
    #21
  2. chasbmw

    chasbmw Long timer

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    Does your bike have a fiberglass tank?

    If so you need to seal it before it dissolves in a sticky goo.

    Rumor has it that one of the reasons that the combat engined bikes eate their main bearings was that the the ignition timing would drift under vibration due to the poor quality of the points securing screws, fitting a Boyer back in 1973 certainly helped my Interstate retain it's tune. No starting problems if you have decent battery and Boyer have fixed the old problem that timing would go to full advance if the battery voltage was under about 10 (?) volts.
    #22
  3. Quickduc

    Quickduc n00b

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    In 1971, Norton used a Japanese main bearing on the timing side. There was something wrong with them. I think it may have been the cage. Anyway, the engine would start to knock around the 8K miles range. Every '71 Norton we sold had this engine failure mode. The factory/importer(US) never talked about this officially. I got the story from our district rep from Berliner (the importer) (our shop was in So. NJ). My Norton was the first local bike to fail. On vacation in FL :cry

    It was not a catastrophic failure mode, although if you ran it long enough it might have turned into one. I had an oil pressure gauge mounted. Changed the oil at a bike shop, where my friend had the head (or base) gasket changed on his Norton. Discovered, after draining it, that the only oil they had was Castrol, which didn't have a good reputation then, IIRC. We were heading home directly. First gas stop about an hour later, the idle pressure was very low, when it normally would have been around 50 psi. And it had a vibration.

    Ran it like this from Ft Lauderdale to Orlando, where I tore the timing cover off and flushed out the metal debris in the engine. Took the oil pump apart and dressed up the surfaces as well as possible (all this in the motel parking lot), and we then continued on to Jacksonville FL, to a Norton shop where a mechanic I knew crated it and shipped it home for me.
    #23
  4. Voltaire

    Voltaire Bored Of The Rings

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    Hmmm, Japanese bearings....first time I have heard that one.
    sounds like one of my suppliers blaming Chinese parts for his equipment failure :rofl
    My understanding is that they pushed the design of the 1949 Bert Hopwood 500 just a bit to far with the Combat engine, raised the comp with the shaved head, different cam, 32mm carbs and the poor old bearings did no like it so they detuned it and fitted barrel rollers.
    I like the growl of my Combat when it hits 5000 rpm :evil

    Resist the urge to restore and just ride it, there are too many restored bikes around these days.
    #24
  5. HapHazard

    HapHazard Waiting for Gudenov

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    Well, seeing that quite a few folks make a good case for the points ignition, (and it's already there:D), I put my new battery in, and gave a kick and yep, nice sparks are still there. I will check the advance unit as suggested, though I am still considering Pazon.

    Speaking of the battery, is there an improved method or device for holding the battery? When I got my bike, it had NOTHING holding the battery down. I then got the genuine NOS battery bar and a pair of the NOS elastic straps (which were deteriorated and useless). I ended up making up an improvised innertube rubber band arrangement that works, but is much less than great.

    Quicduc, I'm sorry to hear that your riding was cut short by a stroke! My friend had a stroke a year ago, and is still recovering, but not riding, but is hopeful. I remember the Cycle magazine articles about using car coils to replace weak bike coils. I'd imagine that now some of the aftermarket coils would be an upgrade without the difficulty of mounting two large coils on the Norton (there's not a lot of room on it). My 73 Bonneville 750 developed a bad primary side main bearing on the longest trip I ever took with it (to Loudon), I rode it home, but man it was LOUD by the time I got back!
    #25
  6. chasbmw

    chasbmw Long timer

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    Norton blamed the bearing suppliers, but the fault was theirs.....they had got Lucas to save a penny by playing around with the points securing screws......
    #26
  7. Quickduc

    Quickduc n00b

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    Voltare:

    you're forgetting that I was the mechanic that rebuilt most of the bad '71 engines at that shop. My bearing was a Japanese, but I don't think I bothered to check the rest of them. The cage was mostly gone. I think one or two balls were also missing. Hard to tell without the cage holding them in proper spacing. That bearing fiasco had a definite impact on future sales of Nortons.

    None of those bikes were Combat engines.

    HapHazard:

    If you can afford it, I would suggest replacing the carbs with twin Mikunis. The stock Amals are lousy, compared to them. I would not bother with the single Mikuni setup. Better fuel mileage, but that was the only thing good about it. I had a British bike mag with a test of the '76 Norton Commando, and it used a single SU(?) carb. It stated 11% power and 10% mileage increases, IIRC. Ugly bike, all angles and flats, looked like a cheap Yamaha of that vintage. Obviously, that worked much better than the single Mik!

    The disadvantage of the dual Mik setup was the fat carbs are splayed apart, and don't allow the stock airbox to be used.

    BTW, the stock coils produced around 8kv. The typical car coil was 16-18kv, and the enhanced about 22-25kv. ( IIRC )

    A word of caution: Do NOT attempt wheelies with a Norton. The transmission is the weak link of the drive train. If you are lucky, you will only knock a tooth off the layshaft 4th gear. Bad luck will cost you the main case, or most all the internals, or both. :eek1

    That is why the factory put those damned fibre clutch discs on the 71's. They are designed to have a soft engagement, but they glaze up and start slipping with few miles. Had to soak them in brake cleaner, and scuff them with sandpaper on a regular basis. The fix is to get the original '69 vintage plates. That is a metal plate with little pads bonded to them. Bare in mind, that they make it easier to damage the trans if you are ham handed. The reason is that when you release the clutch lever, when it hits the end of it's travel, the clutch is locked up. It will not slip, unless you are running a fully built performance engine. The glazing problem is why they went with the 5 plate bronze clutch, which is a marginal improvement.
    #27
  8. pommie john

    pommie john Long timer

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    What bearing were they using on the drive side? They'd gone over to superblend by then surely?

    I use a Japanese ball bearing in the timing side with no problems so far. I think it's an NSK . But most people, I think, use a superblend on both sides.
    #28
  9. Quickduc

    Quickduc n00b

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    John,

    The OEM drive side bearing was not a barrel roller type (superblend) in those engines. Replacements were, FAG brand. Funny name, sticks in my mind. That went in both sides. Damned expensive bearings! As to what the original bearing was, I think it was a roller, but I'm not positive. My recollection is that it was noticeably different from the timing side bearing, which is why I think roller, but I wouldn't bet the farm on it. Some of my memories are fuzzy, whether due to brain damage or age related is unknown. :cry
    #29
  10. Voltaire

    Voltaire Bored Of The Rings

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    I think the Superblend came in during the Combat fiasco, when bikes were being sent back to the factory to have the motors rebuilt.
    The bearing was the symptom, the problem was trying to make a 1949 500 into a fire breathing 750, the low gearing and young fellas thrashing them.
    I don't thrash my Combat as I have a mental image of the bolted up crank flexing and trying to get out of the crankcase....:rofl
    My airhead BMW racer on the other hand I run to the redline of 7500 happily.
    The early 70's must have been a fun time to have been around in the bike industry with the Japanese invasion.
    #30
  11. HapHazard

    HapHazard Waiting for Gudenov

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    I pulled off the Amals today - and man were the slides sloppy! Large areas of the bottom of the bodies were worn/polished shiny (couldn't get a decent picture or I'd post it). Took one apart, and it wasn't really dirty at all (I stopped running the bike years before we got ethanol gas and I'd drained it, too). Maybe I'll mock up the twin Mikunis, but I'll probably order new Amals this weekend. (I'd miss the smelly gasoline finger too much:lol3).

    BTW, no wheelies for me - no danger there!
    #31
  12. Quickduc

    Quickduc n00b

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    The Combat motor was not available in '71. Hmm, need to check my files...

    Ok, according to some 30+ year old documentation, the engines were built with double roller main bearings nearly 1000 bikes before the first Combat engine. In 1972. However, these were apparently not the barrel roller type!

    So, it would appear that the factory had two separate main bearing screw-ups. The one in '71 with the bad batch of Japanese ball type on the timing side, and in '72, when they seem to have tried to use flat roller types on both sides.

    I suspect that the second was in response to the first problem. The higher power Combat engines would cause more stress on the crankshaft, so it would be logical for main bearing failures to show up more often, or sooner, than on the standard engines. So, the Combat engine would be blamed as the cause, at least initially. And that would stick in the public's mind.

    The factory swapped superblends for the plain rollers in every combat engine they had on hand, and also started converting them back to standard spec at some point.

    If your Combat has superblends in it, don't worry about thrashing on it. (Just mind the redline) I've built a couple engines that make the Combat seem rather pedestrian. Had to figure out a clutch setup to handle the HP, as they would slip very badly when they hit the start of the powerband, in any gear. Both 750 and 850 versions.
    #32
  13. Steve G.

    Steve G. Long timer

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    Very incorrect information.

    In fact, the main bearings were not Japanese [who make very good bearings BTW] , but quite good German FAG bearings. The whole main bearing fiasco started with the introduction of the Combat tuned engine which caused the crankshaft to bend under the added compression. This caused massive and quick damage the bearing races. The fix of course was the introduction of the 'Superblend' main bearing, with barrel shaped rollers allowing the crank to bend when forced to, causing no damage to the mains.

    The bike in question, the 850, has Superblends installed from the factory, as well as massive structural ribbing in the crank cases,,,,the bottom end of a 1973 750 and all 850 Norton is almost unburstable, the week link arguable on an 850 is probably the aluminium rods.

    Now, BSA A50/A65 engines had a significantly taxed and under-engineered timing side main bearing bushing rather than a bearing, could this be what you remember?

    BTW, the bearing issues that Norton had to deal with was the dreaded Portugese bearing fiasco, but that was mainly with the layshaft gearbox, and exclusively with the Mk111 Commandos.
    #33
  14. Quickduc

    Quickduc n00b

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    @ Steve G:

    Did you bother reading any of my posts? There are only 5 prior to this one. Or is this some sort of knee-jerk reaction to new (to you) info that might conflict with your world view?

    I prefer to deal with facts, not opinions. I thought my experience with Norton, dated though it is, might be useful to current Norton owners.

    Were YOU involved with Norton Commandos in any official capacity back when they were current? I'm not going to search your posts for your background. Way too many to do that :eek1

    I stated mine in my first post.

    I'm not looking for a pissing contest here. Better things to do with my time.
    #34
  15. Steve G.

    Steve G. Long timer

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    I'm not here looking to offend anyone. Clarifying is the least I can do.
    #35
  16. Steve G.

    Steve G. Long timer

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    Gosh, nice bike! You've got real nice stuff. 18" Borranis? Love the brakes, the nice custom bent fender stay around the caliper, seemless peashooters,,,,,,,,,,
    #36
  17. Woody2627

    Woody2627 Skinny Decaf Latte Thanks

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    At the risk of getting involved in a pissin' contest, this is how I remember the Combat situation was. NVT might have said it was a Japanese bearing failure, but they wouldn't admit to a design flaw, would they?
    #37
  18. chasbmw

    chasbmw Long timer

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    What I read was that the problem was down to ignition timing slipping, because norton had altered the points spec to save a penny.
    #38
  19. HapHazard

    HapHazard Waiting for Gudenov

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    Before everyone loses their bearings entirely, what aircleaner(s) are available if I choose to try my dual 34mm Mikuni setup? It looks really close side-to-side for pods, and not much depth to the battery/oil tank?:ear
    Thanks again!
    #39
  20. Steve G.

    Steve G. Long timer

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    There are alot of options. My buddy has the Sudco single Mikuni kit on his Mk1a 850. He was able to source a thinner air filter to use the original airbox back plate, and a front plate with a single orifice for the single carb. The thing runs very nice, and 'almost' retains the handsome [IMO] original airbox rather than the standard pod filter/s.
    #40