Dyno run (2017)

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With modified bikes and different dynos it's difficult to compare things.
Stock 650 Triumph Bonneville and stock 750 or 850 Commandos have been compared on the road.
The stock Commandos are a big jump up in power from a stock 650 Bonny.
They leave a stock Bonny for dead.
It's even worse when you put a Commando up against a 650 BSA.

Glen
 
Yes, a stock 750 Commando is quite a bit faster than stock 750 Triumph. ...But the dyno charts shown here are not all stock engines and they are being compared. ..Well tuned stock 750 Commandos with gearing for acceleration are capable of 12.6 or so 1/4 mile times...I was expecting to see 60 plus RWHP from modified street Nortons.
 
The 48rwhp bike at the start of the thread has a single Mikuni 34 VVM. Removing twin Amals and replacing with a Mikuni 34 is a modification which removes a good deal of the stock horsepower.

Nigel's twin carb modified street 850 made 62 on a Dynojet dyno.

Here's a 750 racer that eventually made 76rwhp



Glen
 
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worntorn said:
The 48rwhp bike at the start of the thread has a single Mikuni 34 VVM. Removing twin Amals and replacing with a Mikuni 34 is a modification which removes a good deal of the stock horsepower.

Nigel's twin carb modified street 850 made 62 on a Dynojet dyno.

Here's a 750 racer that eventually made 76rwhp



Glen
Click to expand...

That’s a short stroke Norton. Not really a fair comparison.
 
None of it is really "fair" once you start comparing modifieds. All fun to look at though.

Glen
 
Fair or not, it is useful knowledge, if you do this, you will see x, it is handy and gives an appreciation of how far you can go and what would be needed to get there.
 
Madnorton said:
..............and what would be needed to get there.
Click to expand...
Agree it will give one some idea of what it takes but unfortunately, the devil is in the details, way deep in the details. Rarely have I seen adequate documentation that will yield an “if you do this, you will see x”. I enjoy reading about it all.
 
Madnorton said:
Fair or not, it is useful knowledge, if you do this, you will see x, it is handy and gives an appreciation of how far you can go and what would be needed to get there.
Click to expand...

And sometimes, we get an appreciation of how far you shouldn't go!
It does seem like the 850s can be pushed to 750 Combat spec and live for awhile. A MK3 engine with its stronger crank and cases has the best odds at long term survival.
If we go too far with mods then we break the same stuff Steve Maney and others broke decades ago.
And then there is that poor old transmission, amazing as it is. Designed for about 20 HP and mildly upgraded thru the years, a good stock 850 is really testing its capability already.
What happens if we add 10 bhp and really put it to use?
Great fun tho!

Glen
 
I have a Mk3 that I bought in 1985, gradually developed into current incarnation:oversize inlet and exhaust valves by Mr Monning, PW3 cam, gas flowed by Fred Barlow, polished lightened rockers maney barrels and pistons moderate compression increase, 5speed in quaife case and FCr flatslides. I am not an engineer by any stretch, Just like a bit of oomf to suprise the modern stuff.
I am constantly and pleasantly suprised at just how tractable the bike is in traffic and city streets, yet still gets up and goes with little prodding. After reading all this I am now condemned to have it dyno'd, or is it ok to just enjoy the shit out of it without know what its various and unconfirmed HP might be?
 
Men like numbers to analyse and quote even if they haven't a lot of meaning.
Example-
Last summer a friend and I had a good discussion on the weight/ horsepower numbers of the two bikes we were out touring on.
His was a BMW R1200 RT
110 HP ( manufacturers rating)
505 lbs dry
170 pound rider, so bike and rider + fuel = 710 lbs+-
Mine was a Triumph Thruxton R
97 HP
448 lbs dry + 230 lb rider and fuel= 710-720 lbs +-

So same weight bikes, but the rt has 13 more HP. Got to be a lot faster than the Triumph.

We decided to run them against each other.
The 97 horsepower Triumph left the 110hp rt for dead in every gear, every time. 20 mph Higher top speed as well for the Thruxton.
It didn't walk away from the RT, it flew away.
So a few hp one way or the other on paper ( even 13) seems to be pretty meaningless.

Commandos seem to be a bike that performs great on the road, not so much on a dyno.

Glen
 
worntorn said:
Men like numbers to analyse and quote even if they haven't a lot of meaning.
Example-
Last summer a friend and I had a good discussion on the weight/ horsepower numbers of the two bikes we were out touring on.
His was a BMW R1200 RT
110 HP ( manufacturers rating)
505 lbs dry
170 pound rider, so bike and rider + fuel = 710 lbs+-
Mine was a Triumph Thruxton R
97 HP
448 lbs dry + 230 lb rider and fuel= 710-720 lbs +-

So same weight bikes, but the rt has 13 more HP. Got to be a lot faster than the Triumph.

We decided to run them against each other.
The 97 horsepower Triumph left the 110hp rt for dead in every gear, every time. 20 mph Higher top speed as well for the Thruxton.
It didn't walk away from the RT, it flew away.
So a few hp one way or the other on paper ( even 13) seems to be pretty meaningless.

Commandos seem to be a bike that performs great on the road, not so much on a dyno.

Glen
Click to expand...

I’d say that’s largely down to manufacturers BS Glen. Perhaps Triumph are more honest / conservative than BMW?

If you really mean top speed Glen (ie max revs in top gear) how fast was that, must be comfortably over 130mph for the Thrux?

At those kinda speeds, the aerodynamic advantage of your slender profiled half faired Thrux would account for most of that 20mph over the ‘barn door’ Beemer I’d say.
 
Just nudging 140 and hitting the rev limiter.

Wind resistance could explain the top end difference but not the big acceleration difference.

Glen
 
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Men around the world are all guilty about lying about certain measurement. Penis length, the fish that got away, etc.

Two others are: exaggerating their BHP up... and their body weight down...!

When the flag drops, the BS stops!

Maybe your pal is less honest than you...?
 
He's a straight shooter, the numbers are all from BMW's and Triumph's official spec listings for those bikes.
Body weight, well we always say Ian would be the last eaten if he was part of a survivor group stranded in the Andes.
He's a string bean, 170 might be an exaggeration to the upside!


Glen
 
Well it has to be something Glen, unless you’ve discovered a whole new branch of physics !
 
My Nourish Dresda was a quick bike, at 84rwhp and being light, it would have been difficult not to be!

I came up against a very nicely turned out 750 Norton, with a well known rider / builder / all round good guy at Snetterton. I wouldn’t normally beat this fella, but Snetterton is a fast circuit and I thought ‘I gotcha today’!

Down the back straight we were neck and neck, I couldn’t gain an inch. But I had to have more power than him! I was confused. And perturbed.

Then, when I was talking to the rider in the paddock the penny dropped, he was about half my weight !!

His name was Norman White. In fact it still is !
 
The BMW isn't making the claimed HP or the Triumph is making more than claimed.
Also, I don't believe the BMW at 505 dry.
It's an enormous bike!
My point is that the numbers on paper don't always translate to on the road performance. But we love numbers!
I'm guilty of this too.

Glen
 
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Motorrad claims the R1200RT to have 505 pounds dry weight

BMW R1200RT
Manufacturer BMW Motorrad
Wheelbase 1,485 mm (58.5 in)
Dimensions L : 2,230 mm (88 in) W : 905 mm (35.6 in) H : 1,430 mm (56 in)
Seat height Adjustable 820 to 840 mm (32.3–33.1 in) Low seat option: 780 to 800 mm (30.7–31.5 in)
Weight 229 kg (505 lb) (dry) 259 kg (571 lb) w/o panniers (wet)
18 more rows
 
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