Classic bike review

Status
Not open for further replies.
M

mcmarvelous

Joined
May 3, 2008
Messages
89
Anyone see the article on 750 or 850?

The power figures were all over the place and the performance of the 850 was very dissapointing as reported. A shame they couldn't get a 'healthy' pair to test in the first place.

The thing that interested me was they said that the mk3 850 was 5 1/2 stone heavier than the roadster 750, which is a lot! i have an 850 mk3, and have never had a 750 for reference. Apart from the starter motor, a bigger seat and tank, where is this extra weight?
 
mcmarvelous said:
The thing that interested me was they said that the mk3 850 was 5 1/2 stone heavier than the roadster 750, which is a lot! i have an 850 mk3, and have never had a 750 for reference. Apart from the starter motor, a bigger seat and tank, where is this extra weight?
Click to expand...

(for the benefit of our non-UK members 5-1/2 stone = 77 lb.)

I think the MkIII's dry weight was mis-quoted in the manual and other literature, and that figure just gets repeated over and over?

When my MkIII Roadster with full starter equipment (and approx. half a tank of fuel) was weighed for its first computer MoT a few years ago it wasn't anywhere near as heavy as the quoted "465 lbs dry" dry = no petrol, oil or tools (475 lb dry Interstate) figure.
 
L.A.B. said:
When my MkIII Roadster with full starter equipment (and approx. half a tank of fuel) was weighed for its first computer MoT a few years ago it wasn't anywhere near as heavy as the quoted "465 lbs dry" dry = no petrol, oil or tools (475 lb dry Interstate) figure.
Click to expand...

Thanks LAB- what did it weigh, roughly?
 
mcmarvelous said:
- what did it weigh, roughly?
Click to expand...


It was around 420 lb if I remember correctly?
The petrol and oil would have been roughly 15 lb of that weight, although the black cap silencers had been replaced with peashooters which must have reduced the weight a little.
 
It would be interesting to take a larger selection of "bog standard" or essentially unmolested Commandos, and see if there was very much variation in BHP and torque produced by them.

Steve Maney told me that with one of his reworked cylinder heads, his cam and his exhausts on and I suppose properly set up carbs and ignition etc, that his engines were making 80+ bhp.(Can't remember the exact figures but definately in the 80's), and that they were still tractable enough for road use.
 
Yes, an interesting article. I always thought the MK3s were an underpowered slug (no offense intended to owners, just the bikes) but the differences in the article were significant. That 4.2 second time from 40 to 70mph is damned impressive. My 850 won't beat it in top, but will in third gear, which, with a 23 tooth gearbox sprocket is geared about the same as a 750 with a 19 tooth in top. The quarter mile times were poor but the hint is the "bogging off the line" comment. Not using proper technique by the sounds of things. The 0-60 times were slow as well. Same reason I guess.
Weight wise, the rear wheel and disc brake must add weight as well, although I've always thought they were about 50 lbs heavier, which would make more sense. 77lbs is a lot. Of course, in the performance testing, the MK3 with a 22 tooth sprocket is going to suffer markedly against the 750 with a 19, presuming that both have standard gearing.
 
The article is in Classic Bike Oct 2009 issue #357 on page 44.
Article states:
750 1/4 mile performance 14.52 sec at 96.7mph
850 1/4 mile performance 15.48sec at 89.32mph

Both seem a bit slow. In 1973 I ran my '72 750 combat (19T counter sprocket as supplied) at the Ontario Raceway 1/4 mile. Result was 12.1 sec at 103mph. The machine was stock/original with fresh tune from Bill's Cycle in San Bernadino. Sorry lost the time ticket over the years, so can't prove it.
 
illf8ed said:
The article is in Classic Bike Oct 2009 issue #357 on page 44.
Article states:
750 1/4 mile performance 14.52 sec at 96.7mph
850 1/4 mile performance 15.48sec at 89.32mph

Both seem a bit slow. In 1973 I ran my '72 750 combat (19T counter sprocket as supplied) at the Ontario Raceway 1/4 mile. Result was 12.1 sec at 103mph. The machine was stock/original with fresh tune from Bill's Cycle in San Bernadino. Sorry lost the time ticket over the years, so can't prove it.
Click to expand...

You should have seen the 300 lb salmon I caught with a Popeil pocket fisherman :mrgreen:

Jean
 
The salmon was only 238#, and it was a Zebco 202 with a charlie brown fishing rod, on 3 lb. test. He gobbled down that catfish stink bait the instant it hit the water.
 
Actually, Cycle magazine ra a 12.69 at 103.68 MPH with a 1969 Commando "S", so a 12.1 from a Combat is plausible as the Mythbusters would say :wink:

Jean
 
Jeandr said:
illf8ed said:
The article is in Classic Bike Oct 2009 issue #357 on page 44.
Article states:
750 1/4 mile performance 14.52 sec at 96.7mph
850 1/4 mile performance 15.48sec at 89.32mph

Both seem a bit slow. In 1973 I ran my '72 750 combat (19T counter sprocket as supplied) at the Ontario Raceway 1/4 mile. Result was 12.1 sec at 103mph. The machine was stock/original with fresh tune from Bill's Cycle in San Bernadino. Sorry lost the time ticket over the years, so can't prove it.
Click to expand...

You should have seen the 300 lb salmon I caught with a Popeil pocket fisherman :mrgreen:

Jean
Click to expand...

Jean,

Just Nortons here. Fish stories are at www.fishtale.com :)
 
And more from Captain Norton's notes website.

If an 850 can do 12.2 at 114, a 750 combat is well in the range at 12.1/103 geared with 19T.


From: Dan Milhone
Date: Wed, 24 Aug 1994 15:03:44 +0800

John asks, in re to Commando:
>If you've got the magazine, what were
>the numbers for 1/4 mile ET and MPH ?

The literature that came with my '74 850 says that if equipped with the 21 tooth sprocket and a small fairing AND tested at 40 degrees F. ambient temp., they ran 12.20's @ 114 mph.

I do a fair amount of racing with my 62 'Studebaker, and I've run the 850 a couple of times, just for kicks. The best I can get, in stock config, 20 tooth sprocket, no fairing, 80 degree temp. was a 13.08 @ 102 mph. I suspect a Honda 750 would be faster, but not by much. The amount of wind, sitting upright at 100+ mph is such that anything above that is really pushing it.

Dan Milhone
 
Jeandr said:
Actually, Cycle magazine ra a 12.69 at 103.68 MPH with a 1969 Commando "S", so a 12.1 from a Combat is plausible as the Mythbusters would say :wink: Jean
Click to expand...

Back in the day Norman White did a 12.24 on a production model, i assume a 750 - the US importer couldn't get the claimed mid 12's with local riders, they were only getting mid to high 13's, so the factory sent Norman out to prove it could be done. He rode a new bike around for a few days to run it in and then did one run at 12.24. A skilled rider and physically small so i suspect Joe Average would be doing well to get into the 13's.
Or at least that is my recollection of the story from our rally a few years back.
 
mcmarvelous said:
Apart from the starter motor, a bigger seat and tank, where is this extra weight?
Click to expand...
The 850 crank is 5 lbs heavier if I recollect properly. Also the barrels are heavier.
 
ntst8 said:
Jeandr said:
Actually, Cycle magazine ra a 12.69 at 103.68 MPH with a 1969 Commando "S", so a 12.1 from a Combat is plausible as the Mythbusters would say :wink: Jean
Click to expand...

Back in the day Norman White did a 12.24 on a production model, i assume a 750 - the US importer couldn't get the claimed mid 12's with local riders, they were only getting mid to high 13's, so the factory sent Norman out to prove it could be done. He rode a new bike around for a few days to run it in and then did one run at 12.24. A skilled rider and physically small so i suspect Joe Average would be doing well to get into the 13's.
Or at least that is my recollection of the story from our rally a few years back.
Click to expand...

I was Joe Average back then and took my 69 S to the drags, the best run I did was 13.995 @ 91 on my final and last run of 3, the gearbox casing had broken again, I still rode it home like that (about 100 Km). On another run, I had a lower ET 14.025 but a higher terminal speed at 93.26. The class I was in was CC/S which at the time was for stock bikes with gas. I probably weighed somewhere between 170 and 180 pounds which is probably 50 to 70 pounds over the flyweight runts running in the low twelves on stock Commandos, the total weight is very important in order to acheive low ETs.

Jean
 
I ran a 14.00 ET, 98 and change with a 69 Commando back in 1972. Guess my reaction was a bit slow. I was running a Norris "R" cam and a 19T sprocket.
 
Status
Not open for further replies.

Similar threads

Fast Eddie
JS lightweight pistons and rods
Replies
13
Views
885
Hortons Norton
Hortons Norton
Q
'73 750 progress report
Replies
9
Views
329
grandpaul
grandpaul
W
750/850 weight comparison
2 3 4
Replies
75
Views
4,746
worntorn
W
W
Identify bike
Replies
4
Views
403
L.A.B.
L.A.B.
Q
Replacing air filter and screen
2
Replies
27
Views
1,133
marshg246
marshg246
Back
Top