sensibly moded 75 850

A friend of mine wants to sell his 71 BSA A65 and use the money toward a 75 850 Norton.
He wants this year for the Electric Start.
I have only had a late 60s N15 and a couple of early 70s Commandos.
When he is looking for the 75, what up grades should he look for or do after he gets a bike?
I've mentioned the Dyno Dave wiring and starter up grades and the Master cylinder sleeve.
I'm just looking for sensible upgrades to a daily driver making her easier to use and maintain rather than more of a road burner.
I will tell him about about this site and the information found here.
Thank You for your help. Frank Coleman

I wouldn't look for a mk3 just because of the electric start.

You may find a tidy older model, which you could fit an electric start conversion to.
It's a simple job, and you'd have a much more reliable and better engineered starter at the end of the day!

Other benefit to your friend is that an older Commando will be a right hand gear change - whereas for the mk3 they swapped to left (although it's easy to convert, it is at least something to bear in mind)

gtiller said:

Other benefit to your friend is that an older Commando will be a right hand gear change - whereas for the mk3 they swapped to left (although it's easy to convert, it is at least something to bear in mind)

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Interesting :? As far as I know it takes a lot of part changes to swap MK3 left gear change to the right. Please enlighten your easy convert :?:

Frank
By far the MKIII needs the upgraded 200w 3 phase alternator more than the usual humongous battery that some guys put in. After that a good EI that does not kick back. If the original 2 brush starter is NG, then my starter is a good alternative. I love my MKIII's (got 3 of them).

The biggest problem that almost universally afflicts these are the soft cam. You should get proof of a hard cam replacement or buy the bike cheap. I have a new never registered bike with only 5 factory test miles that WILL get a new cam before I put it on the road.. I have NEVER pulled a MKIII cam out that was over 19-25RC. I have pulled out a lot of MKIII with bad cams...I have never pulled a regular commando cam out that was with a wiped out lobe. Am I just lucky?
http://atlanticgreen.com/hscam.htm

I had understood from several people I've spoken to that it is easier going from left to right, as the mk3 primary chain tensioner can stay as-is, which means the gearbox doesn't need to be swing to tension it.

Biggest cost is inner and outer gearbox covers, plus ratchet - all of which can be sourced new or from eBay.

Swapping the other way would be a whole different story though, and probably cost prohibitive for most.


I have been told that it's not too complicated to relocate the brake master cylinder to the other side... I sincerely hope that's true, as I'm playing with doing exactly that on a bike at the moment!!!

Anyway, we digress from Frank's question.

dynodave said:

Frank
I have pulled out a lot of MKIII with bad cams...I have never pulled a regular commando cam out that was with a wiped out lobe. Am I just lucky?
http://atlanticgreen.com/hscam.htm

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My MkIIA had a soft cam so I'm guessing the problem was just fully established for MkIII production, but not exclusive. I'd certainly be budgeting for a cam replacement.

B+Bogus said:

dynodave said:

Frank
I have pulled out a lot of MKIII with bad cams...I have never pulled a regular commando cam out that was with a wiped out lobe. Am I just lucky?
http://atlanticgreen.com/hscam.htm

Click to expand...

My MkIIA had a soft cam so I'm guessing the problem was just fully established for MkIII production, but not exclusive. I'd certainly be budgeting for a cam replacement.

Click to expand...

So did my 04/74 mk2.

dynodave said:

I have NEVER pulled a MKIII cam out that was over 19-25RC.

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New Andover Norton cams are supposed to be better since Mr. Seifert took quality control to a higher level. Does anyone have experience with these cams :?:

I dont understand why you would want to change shifter one either one. Ride it and deal with it. I switch mindset all the time going from the HD to the Norton.
Doesnt make sense to change anything.
Part of my Norton experience is the original right side shift. When you talk to folks about the bike they see the differences and cant believe that its backwards. If they only knew about the positive earth.

My opinion would be the opposite. I can never get on with having bikes with different shift pattern and side
of operation.
I have all three of mine the same so I dont end up breaking me or the bike.

That bit about the master cylinder sleeve - was that about achieving more purchase on the single disc front end ? I tried racing using a chrome plated single disc with a Lockheed AP calliper - hopeless ! I found that using the master cylinder intended for the single disc with two AP callipers and two hi-speed steel Suzuki discs is superb.

If you are not racing, adjusting to the gear shift on the wrong side is not a problem - just takes a bit of time. I really dislike changing between bikes which have different gear-shifts when I go racing - too easy to do the wrong thing if you have a momentary spot of bother. One of my friends was a very good A-grader in years gone by - he has no problem changing between different types of bikes because he has had a lot of sponsored rides. It is all in the mind.

B+Bogus said:

My MkIIA had a soft cam so I'm guessing the problem was just fully established for MkIII production, but not exclusive. I'd certainly be budgeting for a cam replacement.

Click to expand...

I know that most guys here turn their own wrenches but the above post got me to wondering..........
how much would a guy budget for it?
Anybody want to guesstimate how much $$$ it would cost to have a shop swap out a MK3 cam?
I can't imagine that it would be cheap.

When I first purchased my MK3 and rode it out to a local Vintage bike show, a long time Commando owner came over for a look.
His comment about the MK3 was that. "it came from the factory with all of the upgrades and improvements most of us are trying to add to our early bikes"
I didn't know much about the differences other than e start. I bought it mainly because it was close by and in nice condition. The start seemed a nice bonus.

They are very smooth bikes. This may be due to the MK3 type isloastics or the MK3 isolastic head steady.
The bike is somewhat heavier than the preceding 850, though not a huge amount. The main difference is the added weight of the starter system.

The extra weight of the e start is about 25 lbs as near as I can figure.. There are also a couple of pounds of extra metal in the crankcases (pounds well spent) and in the sealed strengthened swing arm ( ditto)
The MK3 model gets a bad rap for being a slug mainly due to the fact that the factory went "Whisper quiet" with the exhaust and the engine couldn't breath.
With open exhaust and a slight compression bump, they run great, pull hard just like the earlier 850s.
Here is a thread discussing the differences between the MK3 and the preceding models.


My MK3 has 26,000 miles on the stock cam. The engine itself has never been apart other than head removal to replace a blown head gasket.

mk3-changes-from-models-t21935.html

gtiller said:

I have been told that it's not too complicated to relocate the brake master cylinder to the other side... I sincerely hope that's true, as I'm playing with doing exactly that on a bike at the moment!!!

Click to expand...

You can do it it by using the stock setup with a few simple modifications.

nortonspeed said:

dynodave said:

I have NEVER pulled a MKIII cam out that was over 19-25RC.

Click to expand...

New Andover Norton cams are supposed to be better since Mr. Seifert took quality control to a higher level. Does anyone have experience with these cams :?:

Click to expand...

Only bought one AN (BSA Regal not Seifert) chilled iron cam. Split on the casting mold joint line which lines up perfectly with the center of the first lobe. They claimed we over torqued the bolt and the AA unit split the cam. I took a new factory AA bolt and put a torque wrench and broke it off at about 14 ft/lbs and it did not harm a real NOS Norton factory (not AN) 06-1084. It took a long long time but they eventually warrantied it.
Yes I heard of some 74 with soft cams too, and yes I heard of some 75 MKIII that get over 10k before the cam went bad, but the % of low mileage wiped out mkIII cams is way to high for me.
I will be rebuilding a club members MKIII and he had bought a chilled iron cam and I told him to dump it. So keep an eye out for a cheap new cam on ebay if you want one. We're again going with steel.

I think it would be great if AN offered a real steel 06-1084(50+RC) and if they must... 06-1084ci. Then they could feel like they are not constantly misrepresenting about "being made to original specs and drawings"... like soft spacers between the rear wheel hub bearing and brake drum bearing or soft as butter g-box sprockets...and on and on

Of all the "upgrades" so far to my '74, the front brake has had the largest impact on every ride we go on. An aftermarket 12mm M/C with Blanchard-ground disc to remove the chrome made a huge difference in its manners.
Next would be LED headlight. Either using the stock reflector led-headlight-t25409-30.html#p336256 or swapping to an H4-compatable unit permanent-solution-dim-commando-headlight-t20361-15.html#p263301 I had originally added relays while running the heavy current draw of an actual H4 bulb, but probably wouldn't if going to an LED, due to their much lower current requirements.
I'm partial to my '74, and, rather than switching to a MkIII, will look at upgrading with an aftermarket e-start once my knee caves.

Nathan

I think that many guys don't realise the front brake determines how fast you can go.

+1 on the front brake.

Next on my list would be the electrical. A 40 year old loom with various alterations and additions is the part most likely to create a breakdown.
I really need to rewire my MK3 soon.
Another MK3 upgrade that is in the works would be high grade steel CNW starter drive wear parts. Matt is planning to offer these soon and I'll be ordering.
As far as the engine/trans and clutch go, it already runs smoothly and has good power. It shifts perfectly. The clutch, with minor fettling and Barnett plates, is a one finger deal and very progressive, nice to use.

If the engine was tired and in need of a rebuild, then by all means, utilise modern stuff.

When the original concentrics get sloppy and hard to tune, slap some Amal Premieres on there.

Suspension is another on my list of "don't does" for now. I was ever to make a change, it would be to add the Landsdowne dampers, about to be available again.
But really, as it is, it goes down a rough road better than my Thruxton R with the Ohlins and Showa Big Piston forks. That is, it has a less jarring ride. For rough asphalt, it's the best riding bike I own. I've never bottomed the forks and I've never heard them top out. What am I doing wrong?
Seems to handle OK too.

Maybe the extra weight of the MK3 helps soften the ride?
Another concept I don't understand is altering the internals of a MK3 in hopes of making it smoother. This one is smooth as glass from 3,000 to 7,000 now. Maybe I'm lucky, but the bike is already much smoother than either of the two modern BMWs I rode this summer or the 02 Guzzi Lemans I sampled last summer.
In it's smooth band it is as smooth as either of my new Triumphs with their balancing shafts. And they are wonderfully smooth.
Where can you go from there?


Glen