Mark 3 verses the rest

In 1976 I rode my mate's 750 Commando/Featherbed for the day after riding jap dirt bike for a few years before, I was very impressed with the way it went (hot motor etc) so 2 weeks later I was at my Triumph/Norton/BMW/Harley dealer and they had all the latest 75 M111 Commandos and right down the back was a lone old stock 74 Commando sitting all by itself with its pea shooter mufflers and that's the one I brought, $1999 on the road the M111 was $450 more, weight 35lbs heavier and as the sales man explained the ES was a kick start helper.
$450 might not seem much but back in 1976 $450 was a lot of money as my work wages was only $60 at the time and had to get a $1100 loan to pay for the Norton, witch I paid off in 9 months.
After 46 years of owning my Norton and the changes I made to it convertion to Hot 850 Commando/Featherbed frame back in 1980 and still the same today, over the years I have worked on a lot of Norton's from 650 Dommie's to 750/850 Commando's, have never worked on a M111 but have rode a few over the years and as fullauto said each one is different, each handle differently and everyone will have their pick of the bunch, all I know is I have a love of all Norton's, I still kick mine over easy with the kicker, been doing it for over 46 years now, with the Joe Hunt maggie it fires up on 1/2 swing on the kicker once its been started for the day, so no need for a ES at this stage, but then I have 2 Triumph Thruxton's for push finger starts.
A few of my mates are arranging a ride soon only kick start bikes allowed, be interesting how many turn up as these days kick starting a bike is a dying breed.
I also have no problems with the gear change from my modern bikes to my Norton and really my right hand gear change is the smoothest of all my bikes.

Ashley

An old racer friend came up with his ex race bike a 750 Triumph with a Track master frame now all set up with modern dual discs and a real tricked out improved bike, we when for a ride in the city and I was leading to show him the way to the place we would eat. I was just giving my then stock MK3 squirts of throttle between stop signs and the city blocks. When we got home, he said he really had to wick up his bike to stay up. I told him "Gary , I was only giving it 1/2 throttle and not grabbing the second handful."

He then hunted out a MK3 to buy. When I did the rework on the bike as the MK3 cam had two severely worn cam lobes, I showed him the cam and also saw that I had a 22 tooth front sprocket, that I forgot I had put in, he was even more shocked that the ill running MK3 had so much grunt. Now with a WEB Cam and a 20 tooth sprocket and a 30 MM head and a shaved head, It's a whole other animal. And a half twist of throttle makes the bike feel like the race bikes I rode years ago. A fresh engine and a good head work wonders. The MK3, now can just do an easy roll out, now and when I grab a handful of throttle go like a bat out of hell an flies. All Commandos have the potential, even a well set up stock bike.

ashman said:

2 weeks later I was at my Triumph/Norton/BMW/Harley dealer and they had all the latest 75 M111 Commandos and right down the back was a lone old stock 74 Commando sitting all by itself with its pea shooter mufflers and that's the one I brought, $1999 on the road the M111 was $450 more, weight 35lbs heavier and as the sales man explained the ES was a kick start helper.
$450 might not seem much but back in 1976 $450 was a lot of money as my work wages was only $60 at the time and had to get a $1100 loan to pay for the Norton, witch I paid off in 9 months.

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I bought my MKII in May of '75, there were MKIII's on the dealer's floor at the time. Paid $2450 for the MKII, the MKIII's were $2999. I, too, was making peanuts for a wage, but the local bank gave me the loan.

3 months later I visited my dealer and the prices had dropped by $500.

Carl H said:

An old racer friend came up with his ex race bike a 750 Triumph with a Track master frame now all set up with modern dual discs and a real tricked out improved bike, we when for a ride in the city and I was leading to show him the way to the place we would eat. I was just giving my then stock MK3 squirts of throttle between stop signs and the city blocks. When we got home, he said he really had to wick up his bike to stay up. I told him "Gary , I was only giving it 1/2 throttle and not grabbing the second handful."

He then hunted out a MK3 to buy. When I did the rework on the bike as the MK3 cam had two severely worn cam lobes, I showed him the cam and also saw that I had a 22 tooth front sprocket, that I forgot I had put in, he was even more shocked that the ill running MK3 had so much grunt. Now with a WEB Cam and a 20 tooth sprocket and a 30 MM head and a shaved head, It's a whole other animal. And a half twist of throttle makes the bike feel like the race bikes I rode years ago. A fresh engine and a good head work wonders. The MK3, now can just do an easy roll out, now and when I grab a handful of throttle go like a bat out of hell an flies. All Commandos have the potential, even a well set up stock bike.

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Which WebCam Carl?

I think my 750 is turning into a MK3 tribute bike
It has a cotter pinned swinging arm
MK3 Isos
MK3 timing cover
Electric start
Disc rear wheel !!!

MichaelB said:

Which WebCam Carl?

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Just a WEB 12. Luckily I had two cams done years ago, so I have a 12A made up at the same time, they were about 1/2 as much then as now. . I did have to make a valve pockets in the pistons as I have no base gasket and a shaved head. It did not have as much lifts as the specs said , But it degreed in just the way I like it. WEB is my choice on cams. With all 5 types of WEB Cams I've used, NO one ever accused my bikes of not being fast. Great power all over the place too, from low to high revs.

Many years ago I fitted an engine / gearbox cradle from RGM which is like one for a Mk III but modified for MK II and
fitted with double cotter pins for the swinging arm spindle like the MK III and can accommodate the swinging arm
and drum brake of MK II. RGM still sells their modified cradle

worntorn said:

When replacing the black caps with open peashooters the main jet goes from 230 to 260 and the engine wakes up.

Real world, my 850 in a 5 mile drag up a steep mountain pass pulled ahead of a Vincent 1000 by half a mile at top. The MK3 held 95 mph on an 8 % grade. The only performance changes from stock are the exhaust and a bit thinner head gasket.
The 750 in our club doesn't pull like that, it tends to get in the way of the Vincents when passing uphill.
I was surprised that the MK3 outran the Vincent. So was the Vincent owner!
Glen

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If you had raced the Vincent at speeds over 100 MPH, the story might have been different. A Vincent uses a lot less revs and usually pulls much higher gearing. I rode one years ago and I wondered where all that urge was coming from. If you lowered the gearing on a Vincent, it probably would not accelerate any faster. It would just make more noise. When I was a kid, I used to hot-up Triumph 650s. My mates had Vincents. The Triumphs would easily beat then to 100 MPH - but not beyond that. The trouble with Commandos usually comes with high revs. The crank balance factor is set to be best at low revs and the isolastics cope with the rest. If you are going to race a Commando, at high revs the bottom end will still cop a beating. Most motorcycles cannot be all things to all people. CB750 Hondas, usually do not handle. To go that bit between 100 MPH and 125 MPH, takes a lot of power. And where can you find a public road where you can do it ?

The title of this thread is "MK III vs the rest" (of Commando models)
And not MK III vs Vincents or Triumphs

A stock '71 Commando would run off and leave a stock Mark III in any gear at any RPM at any time. We did that particular "contest" innumerable times back in the day when the Mark III types bragged about their (semi) electric starters. OTOH the III had better brakes!

BUT, if you asked me which I'd rather have TODAY, it would be the Mark III but that's a function of being old and having a different set of priorities!

I cannot see the point in knocking the MkIII. It was a natural progression with well over 100 (I seem to remember) changes which were supposedly improvements over the MK2a. However, you have to take it in context and look back to see that NVT were fighting for survival. Their biggest market was the U.S. so they had to comply with the rules forced upon them if they wanted to sell bikes there. Gear changes had to be on the left, all switches clearly labelled noise and emissions had to meet tough federal standards. At the time the The Japanese were dumping thousands of bikes at incredibly low prices over there so Harley were also on the back foot and were instrumental in lobbying the government of the day to impose strict import rules and taxes on all motorcycle imports. NVT products were in direct competition to Harley, so had a double whammy to contend with. Yes, some had camshafts manufactured by Cadbury's and Press-to-dim starters but as others have said on here, it is still a rip-roaring Commando just waiting to be set free.

Personally I like the Annular Discharge pipes, I think they have a certain sleek elegance. ( but then I always liked Rayguns too).

Interestiing Read..

I think the main problem with the MK3 is the large port head once you get over the Swiss cheese cam and the extra weight. .

Carl H said:

I think the main problem with the MK3 is the large port head once you get over the Swiss cheese cam and the extra weight. .

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Hi Carl,
I didn’t realise the head of a Mk3 had different port size. I thought they they ran smaller 30mm carbs compared to the earlier 32s. What is the problem with the larger port head?
I can hardly call being heavier a fault considering it just the addition of a (rather ineffective) starter. Something just about every other bike was equipped with
al

Alan L said:

Hi Carl,
I didn’t realise the head of a Mk3 had different port size. I thought they they ran smaller 30mm carbs compared to the earlier 32s. What is the problem with the larger port head?
al

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The 1975 MkIII has the same RH4 cylinder head as the Mk1 from 1973.
Same head, same cam spec, same piston compression, same 32 / 32 manifolds and carburetors.
Sounds like pretty much the same engine spec on paper.

The Mk2 and Mk2a with the 30 mm port (32/30 manifolds) RH10 is something else.
Calling the RH4 a big port head is a little bit whimsical. (The FullAuto has the same 32 mm at the inlet face)

The RH4 has history of cracking.

Time Warp said:

The 1975 MkIII has the same RH4 cylinder head as the Mk1 from 1973.
Same head, same cam spec, same piston compression, same 32 / 32 manifolds and carburetors.
Sounds like pretty much the same engine spec on paper.

The Mk2 and Mk2a with the 30 mm port (32/30 manifolds) RH10 is something else.
Calling the RH4 a big port head is a little bit whimsical. (The FullAuto has the same 32 mm at the inlet face)

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The RH4 on the MK3s I've seen ain't the same as the earlier RH10. It's just a big straight hole, and It doesn't have the nice taper of an RH10. Some thing has to explain why they are slower. I don't thinks it's all about the black caps as a reason. .

worntorn said:

When replacing the black caps with open peashooters the main jet goes from 230 to 260 and the engine wakes up.

Real world, my 850 in a 5 mile drag up a steep mountain pass pulled ahead of a Vincent 1000 by half a mile at top. The MK3 held 95 mph on an 8 % grade. The only performance changes from stock are the exhaust and a bit thinner head gasket.
The 750 in our club doesn't pull like that, it tends to get in the way of the Vincents when passing uphill.
I was surprised that the MK3 outran the Vincent. So was the Vincent owner!
Glen

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....I just saved myself sixty grand

Your money isn't safe just yet.
Full disclosure, I have a 20t on the MK3. It makes quite a difference on a climb.
Also, this was a solo run for both of us.
Two up... different story.

Glen

MichaelB said:

Interestiing Read..

Geoffrey Roe: The Annular Discharge Silencer

The following blog hopefully gives an insight into the research and development work carried out in the early 1970’s into the efficient...

yorkshireferret.blogspot.com

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Great read. Thanks for posting.

Ken

Big Red my 1975 MK2a with an RH10 ( that is the year the factory paper work said) Could do 100 MPH in the quarter and that is what the speedo read at the stripe, so the Smith gauge was accurate. I had it red lined lined at 7000 on Rt 140 reading 120 MPH a few times. One thing I was good at was a very tight tuck and getting under the wind. Big Red was a real "Road Runner"
Remember The S models were probably the fastest of the 750s Commandos and they has a 28MM port. I think the Combat is not the greatest due to the Cam and the cam timing, I had to advanced my recent reworked Combat 5 degrees to get it near the OEM spec. I think the Combat head it self is a decent port. But I 'd have to drag race them to get a better handle what they do.

Right now my MK3 , Now with a WEB 12 Cam and an RH10 that was on my Maximum Overdrive " Atlas "race bike is scary fast to me, and both the MK3 and Combat haven't seen 7000 yet as I'm breaking them in and I'm limited on the rural roads I'm on, and I'm leery of tearing up the trans gears and speeding tickets and the idiots on the roads. But I can feel them getting faster as they loosen up and the parts are getting used to each other and they get dialed in.