Commando in Context.

Ok, so regarding that [query] Combat tested by Cycle, if they saw a cam marked 'SS' would they have taken it to mean SS [ as in 650SS] or 2S? [Literally 2 S`s stamped]?
H2 cam is in the oil-pump. Cylinder heads have no moving parts & 5 holes -4 to allow sleeve nuts for fastening- & 1 threaded for sparking plug. Range with standard tank - capacity ~equivalent to Interstate - `bout the same as a Roadster Commando?, ~ 100 miles @ 100mph.

J.A.W. said:

Ok, so regarding that [query] Combat tested by Cycle, if they saw a cam marked 'SS' would they have taken it to mean SS [ as in 650SS] or 2S? [Literally 2 S`s stamped]?

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Note that it says: "*Our readings* showed the magic stick to be a slightly worn SS cam instead" which seems clear they discovered this from their own measurements not from just looking at the camshaft.

I will call this whole article a load of bollocks. the H2's I have riding was useless for ANYTHING but a drag race. the fuel mileage was horrible, it DID NOT have any low end torque and the more you revved it the bigger the handle bars got till you could not stand to hold on to them from the vibration.

J.A.W. said:

From M.C.I. Road Test Annual 1974, Dave Minton writes,
"The speed advantage of this machine lying solely in its immense torque spread, allowing big throttle openings from as low as 2000 rpm in top gear. As this is only around 40mph, the usefulness of such a wider power spread can be appreciated fully by riders with experience of long, fast rides when the continual effort of gearchanging becomes a wearying & sometimes painful chore. In other words, the 750, once free of town can be held in top gear almost indefinitely without losing ground during low engine speed operation.
I know full well that Vincents used to do it, & Squariels & other oldies.
What they would not do - & NEVER did, so forget the legends - was to cruise at the tremendously high speeds of this one.
It has no limit. Top speed, which came out at around 125mph, was also cruising speed."
Sound somewhat familiar, Commando riders?
Well, Minton is, in fact, describing the H2!

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Yes, good point L.A.B., I wonder if they were concerned about "cheats" & wanted to check if a cam, possibly a regrind, disguised as - "slightly worn"- or non standard substitution had been made? Has anyone ever heard the story from the tuner`s viewpoint? Slark & Yacenda?
A `72 roadster with 10:1 comp/32mm carbs/disc front end -surely- should`ve been a Combat?
I wonder if that story -telling bloke, Mike Jackson - knows anything about this bike? Did N.V. de-tune it for [safety reasons] the test - Combat-angst?

Well Bill, I can only surmise your anecdotal experience was of a bad one, I suggest you have a look at the dyno charts [H2 delivers more than 40lb/ft TQ from 3,500 to 7500 rpm vs Commando doing 40lb/ft from 5,000-6000rpm], & check out the production racing records [of this part of the world, where production meant strictly showroom stock] where H2s won endurance races [`72 Castrol 6hr] inspite of that thirst.
http://www.the6hour.com.au/content/history1972.html

& in old Blighty where the regs didn`t quibble over showroom stock, in `74 Barry Ditchburn & Kork Ballington put a fat tank & TT100 road tyres on an H2R to knock off the previously all conquering factory J.P.N. team at the Thruxton 500 endurance race.. http://www.mortonsarchive.com/?Action=VF&id=5640598202

Nay , L.A.B. , they diameter of the head of the intake valif , were any 750 heads 1 5/8 in Dia In Valve standard . ???????????

Wondering what we would get out of a decent 750 C'do motor in a 675 Tri Chassis , speedwise . A Norump ??

Matt Spencer said:

Nay , L.A.B. , they diameter of the head of the intake valif , were any 750 heads 1 5/8 in Dia In Valve standard . ???????????

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Ah I see, oversize inlet valves. Well...I've never heard of any standard 750 heads that had oversize inlet valves?

I would say it was the norm for the ones I have seen around my parts. the best use for the tachometer was as a dial gauge to show how big the handle bars grew. as for its ability to go round a corner, after the hinge was found and welded solid it was not to bad i guess. as for proddy rules it is known, it is not what the rule book say's but what it does not say

J.A.W. said:

Well Bill, I can only surmise your anecdotal experience was of a bad one, I suggest you have a look at the dyno charts [H2 delivers more than 40lb/ft TQ from 3,500 to 7500 rpm vs Commando doing 40lb/ft from 5,000-6000rpm], & check out the production racing records [of this part of the world, where production meant strictly showroom stock] where H2s won endurance races [`72 Castrol 6hr] inspite of that thirst.
http://www.the6hour.com.au/content/history1972.html

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Bill, have you ever ridden an Atlas? L.O.L. [Sorry]
How much 2-stroke riding have you done, rather than 'seen'?
A rogue unit [likely in a poor mechanical state] is no basis for a representative appraisal.
From 'Kawasaski Motor Cycles' by Mick Woolett P.64/5; Re that `74 Thruxton race..
"..Kawasaki not only won the event at a record-breaking 86.33mph, but Barry Ditchburn put in the fastest lap at 1:32.4s to set a new circuit record at 91.79mph.
From the start the Norton crewed by Norman White & Rex Butcher shot into the lead, but at the end of the 1st lap Ditchburn was tidily in 2nd place. Alain Genoud on the Bol d`Or winning Egli-Kawasaki was in 4th.
Ditchburn took the lead on the 2nd lap & continued to pull further ahead...at about the 1/2 way mark, after 3hrs of riding the Kawasaki pair led by a lap & a 1/2 after completing more than 100 laps...they led the field after the 1st hr, 2nd hr,3rd hr & 4th hr... The machine had been fitted with an 8 gal tank so needed to refuel only 3 times & the fuel consumption worked out better than the 13mpg anticipated by the team. The bike weighed 300lb & produced about 100hp!" - & the only vibration concern was a snapped exhaust bracket.
Those numbers would make for a handy roadbike today [esp with 2T DFI to tame that thirst], but I`d like to build a ~250lb/80hp Commando too.

let me get this. the bike used almost 24 gallons of fuel in 6 hours and you don't think it is horrible on fuel. the bike you are comparing is over 100 lbs lighter the one a showroom stock and 30 HP over showroom stock. I would guess it was also VERY heavily modified from stock so it was more than likely rebalanced to address the vibration issues along with frame mods to fix the HINGE it came with. so my question is WHAT has this to do with a comparison to a bike me or you got off the dealers floor????? It looks to me like you are on the WRONG forum as you keep talking up your love for a ring ding chain saw!!!!

J.A.W. said:

The machine had been fitted with an 8 gal tank so needed to refuel only 3 times & the fuel consumption worked out better than the 13mpg anticipated by the team. The bike weighed 300lb & produced about 100hp!" - & the only vibration concern was a snapped exhaust bracket.
Those numbers would make for a handy roadbike today [esp with 2T DFI to tame that thirst], but I`d like to build a ~250lb/80hp Commando too.

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Bill, Bill, Bill, can we stay with the facts here, A 120 degree triple [or multiples of 3] is inherently way better balanced than a crank which has the reciprocating masses stopping/starting abruptly over the cycle..
If your experience was a of an H2 that was such a impossibly bad vibrator, then something, - clearly was damaged or mis-assembled, it was not representative of the norm.
So yes H2s have a thirst, no argument, but they put it to good use..
H2s & Commandos ARE relics of their era, but they were perhaps also, the best of their era too, & still give satisfaction for the way they go , now.

The vibration issue is more involved than just the 120 degree phasing of the crank ( which should be better) as quality control can also have a big effect on vibration hence my reference to the re balance as most any good race mechanic would do. Most all H2 owners and the ones I have personal experience with had a high frequency, high RPM vibration issue. It is VERY different than the shaking with a 360 vertical twin but vibration non the less. If you want to look at it from a strictly engineering point than the 750 Honda was the closest thing of THAT era to perfection than the next step was the Z1 not some fuel hungry, smoke spewing 3 cyl. vibrating ding pop.

J.A.W. said:

Bill, Bill, Bill, can we stay with the facts here, A 120 degree triple [or multiples of 3] is inherently way better balanced than a crank which has the reciprocating masses stopping/starting abruptly over the cycle..
If your experience was a of an H2 that was such a impossibly bad vibrator, then something, - clearly was damaged or mis-assembled, it was not representative of the norm.
So yes H2s have a thirst, no argument, but they put it to good use..
H2s & Commandos ARE relics of their era, but they were perhaps also, the best of their era too, & still give satisfaction for the way they go , now.

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Bill, you need to do some more research, the Honda 750 has a 180 degree crank [oddly - used by Laverda for their `70s triple - it ran rough & sounded like a Honda with a dead cylinder] that gives an unpleasant 'busy' vibe. Honda only got smooth running via opposed [gold-bling], inline 6 [CBX/1000]or 360 degree V4 configurations,& in fact a 2 stroke triple has the same firing impulses as a 4 stroke 6, ok, yes there is a rocking couple moment but never vibes enough to require isolastics.[if it were so bad how could they be raced for hours on end?- those Castrol 6 hr rules were strict, Ducati... oops yes, of course my 750 was factory fitted with 900 pistons, -yeah right]
What the Commando & H2 have in common is they are both torquey,light weight, compact,character-building addictive involvement,performance on tap unregenerate old-school superbikes, I like the similarities & the differences, & both are denigrated by people who dont get it, but trade on old horror stories regardless of the facts.

the Honda 4 as all in line 4's are actually 2 180 cranks or 2 360's phased 180 apart as you have 2 up and 2 down. laverda's had both a 360 and a 120 depending year and model. I would put ANY Honda 4 or Z1 against your triple any day for high RPM for smoothness. the rest of your argument ( CBX Gold Wing 6 or V4) is irrelevant as it has moved to the next generation of engineering. How did a Ducati come into this???? but I will say that the duck 90 degree v is a better solution as it has perfect primary balance verses an in line 2-3 or 4 cylinder.

J.A.W. said:

Bill, you need to do some more research, the Honda 750 has a 180 degree crank [oddly - used by Laverda for their `70s triple - it ran rough & sounded like a Honda with a dead cylinder] that gives an unpleasant 'busy' vibe. Honda only got smooth running via opposed [gold-bling], inline 6 [CBX/1000]or 360 degree V4 configurations,& in fact a 2 stroke triple has the same firing impulses as a 4 stroke 6, ok, yes there is a rocking couple moment but never vibes enough to require isolastics.[if it were so bad how could they be raced for hours on end?- those Castrol 6 hr rules were strict, Ducati... oops yes, of course my 750 was factory fitted with 900 pistons, -yeah right]
What the Commando & H2 have in common is they are both torquey,light weight, compact,character-building addictive involvement,performance on tap unregenerate old-school superbikes, I like the similarities & the differences, & both are denigrated by people who dont get it, but trade on old horror stories regardless of the facts.

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Bill, shouldn`t you be on a Honda forum if you rate them so highly?L.O.L.
The Yamaha R1 is an example of an in-line 4 which does not run a 180 crank...
You mistake the configuration for the subjective vibes felt, it is the combustion sequence/power-strokes that provide the dynamic feel, including that annoying busy buzzing that I find objectionable in Honda 750/4s, & while Commandos with 360 degree cranks need isos to stop the primary imbalance produced vibes the combustion sequence provides that nice loping dynamic feel, 120 triples like-wise have a harmony-like feel to the power strokes/riding dynamic that buzzy 4s dont.

Bill, Bill, Bill, can we stay with the facts here, A 120 degree triple [or multiples of 3] is inherently way better balanced than a crank which has the reciprocating masses stopping/starting abruptly over the cycle...

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Don't know if many people have thought about this in the context of a piston engine but, the energy to accelerate the piston back down after a "stop" was stored in the crank shaft/flywheel by the energy of deceleration. The same is true at the other end of the stroke. So, other than the shear strength of the connecting rod and friction losses the actual energy to start and stop the piston at both ends of the stroke is cancelled out.

On a 360 degree twin the force to stop the piston at the top and bottom can be ballanced completely by using a 100% ballance factor. If this is done, however, the vibration will be extreme at 90 degrees to TDC and BDC.

Dan.

So , we set the crankpins at 90 degrees , and are left with a secondary imbalance .And it buzzes like a Jap Bike . :lol:

H2 = highly effecient method of converting petrol to noise . :lol: ( and smoke if theyre prudent )

Highly efficient? H2 fuel consumption? specfic out-put 300gm/hp/hr at 7000rpm , not too shabby for a primitive [uncomplicated] - 3 X 3 moving parts from the crank up, symmetrical piston port pulse-jet, & as for oil, how much do old Brits use/abuse/lose, not really a point of positive pride there, unless as irony..
Point is, thirst is possibly a cheap price to pay , relatively speaking for that unconstrained, eager energy transfer, Combat Commandos are eager like-wise, but not sans fettling, I understand?

120 degree cranks dont 'stop' during reciprocation events, the 'fluidity' of motion/inertia is maintained.
As for "Noise", that term is usually reserved for unwelcome or unpleasant mechanical events transmitted as sound, another thing in common H2 & Commando both have, whether top-end piston slap or thrashing valve gear betraying geometry & etc compromises, but as for the SOUND of POWER via intake/exhaust events, that aint noise, ol`buddy, thats sweet music..