A ride out with modern bikes

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Back in January i bought another MK3 Interstate (the last one i had was back in 1984, lost when I crashed in northern Norway touring Scandinavia) and rode in home over the Pennines, a journey of 120 miles in winter. My son who had gone with me to buy it thought I was mad and although it was a bit cold the weather stayed clear and fine.
Since January i have been gradually going through the bike, sorting out previous owners failings and installing upgrades of my own. The most obvious one being the SU carb and manifold. The bike had been fitted with a single Mikuni. I had fitted an SU to the previous MK3 to increase the range when touring and wanted the same with this one. I finally got hold of an Phoenix Engineering SU conversion from a chap in France, through the NOC.
Back to the ride out. A couple of weeks ago talking bikes with a colleague at work he mentioned that they (the chaps on his shift) were going on a ride out, from Yorkshire, up north to Northumberland for dinner and then back following a set route, No motorways (freeways for our cousins across the pond) just A and B roads. He sent me the route and the start point via email and so I set to getting the bike ready for what turned out to be a great day out, The preparation involved the usual servicing and a load of polishing.
Filling up on the morning of the ride I zeroed the trip. Getting to the meeting point (the Strawberry fields Cafe, just south of York) I realised that my bike was oldest of the group by over 30 years. All of the bikes there apart from the Buell were what I call Spaceships (fully faired sportsbikes) or Transformers (offroad trail bikes ie BMW 1200GS) There were Honda VFRs, at least one Fireblade, BMW1200GS,s Triumph Tigers, a Buell, an Aprila, Kawasakis of various sizes etc etc. A total of twenty one machines, all faster and better braked. Allan (BMW1200GS, the chap who organised the ride) came out with the comment 'when are you going to do the first oil change' (I should explain that the blokes I work with are a merciless bunch of piss takers given the chance) To which I replied "Allan, at the end of the day, my bike will be worth MORE and your bike will be worth LESS" this comment was delivered with the appropriate finger pointing. That shut him up!
Setting off up the road it wasn't long before most of them past me and disappeared into the distance. Upon getting to the first fuel stop/meeting point I realised I was first one there along with the bikes who were content to follow me (I don,t think they knew the route) Ten minutes later the rest of them arrived, victims of following someone using a Satnav. To say I was amused is an understatement. The rest of the day followed much along the same lines. I filled up at Barnard Castle on the way back using 13.5 litres to do 208 miles, thats 70 miles to the gallon (UK gallons) or 58 miles to US gallon or 4 litres to 100kms and that is riding like I stole it!
Quite a few of the other riders were amazed at how little it used and at how well a 39 yr old bike could go. Ha! bring on the next one!
 
Wow. That's amazing! 58 MPG riding like you stole it.. I got 30 MPG last weekend with some extended caning.

I'd always liked the SU since I rode alongside a Sportster fitted with one, 1800 miles, back in '82. he got 50MPG, But that was steady state cruising, 70mph.

Sounds like you had a fun time. Repeat as needed! :mrgreen:
 
WOW from me too! I have never been able to get much over mid 30s MPG out of my Commando - either the current 850 or the 750 I had back in the day. (oem Amals on both)

But I haven't done a real mileage check in a long time - in fact not since we lived in NY so that was 8 years ago. We're going on a ride tomorrow that will total about 150 miles (with the "new" balanced exh pipes). I'll see how it does on MPG.
 
Most of us know squat about fitting an SU carb or maybe it isn't most of us, but I am ignorant enough for a whole group. Details and photos would be of interest. Regarding your comment about the oil change I probably would have said that I don't change it, just replace it, but your comeback was much better!


Russ
 
rvich said:
Most of us know squat about fitting an SU carb or maybe it isn't most of us, but I am ignorant enough for a whole group. Details and photos would be of interest. Regarding your comment about the oil change I probably would have said that I don't change it, just replace it, but your comeback was much better!
Russ
The Norton 76 put together by a small team led by Bernard Hooper as the next development of the MK3 used an SU as he didn't rate the amal carb very highly at all, see the photo here. Bernard Hooper went onto start Phoenix Engineering when he left Norton after they went bust. To fit one is simplicity itself and to tune it is even simpler, all done in five minutes. It takes longer to warm the engine up! I,ll try and take some photos tomorrow of my bike to show you up close
regards
Pete

heavyweight-contender-rope-dope-111-commando-t19951-30.html#p256782
 
dobba99 said:
rvich said:
Most of us know squat about fitting an SU carb or maybe it isn't most of us, but I am ignorant enough for a whole group. Details and photos would be of interest. Regarding your comment about the oil change I probably would have said that I don't change it, just replace it, but your comeback was much better!
Russ
The Norton 76 put together by a small team led by Bernard Hooper as the next development of the MK3 used an SU as he didn't rate the amal carb very highly at all, see the photo here. Bernard Hooper went onto start Phoenix Engineering when he left Norton after they went bust. To fit one is simplicity itself and to tune it is even simpler, all done in five minutes. It takes longer to warm the engine up! I,ll try and take some photos tomorrow of my bike to show you up close
regards
Pete

heavyweight-contender-rope-dope-111-commando-t19951-30.html#p256782

The S U is a far far far better carb then the amal. As a mechanic working on British cars. it was a piece of cake to tune. Lets face it, it was on Rolls Royce, Jaguar, Rover, Austin, Morris [ because it was designed by Morris ], Riley, M G, blah blah blah and so forth. Stromberg made a copy with a diaphragm instead of a piston but the S U is better. [ provided idiots did not touch it, the carb would do 100,000 miles before needing the throttle shafts to be dealt with. ]
If only the SU carb suitable for commandos was available in a smaller size, I would happily fit 2 of them. Unfortunately, the smallest size I know of, is better used as a single.]
BTW, IMHO, the SU was the best thing Nuffields organization designed. The best thing that happened to Morris was to be taken over by BMC, because they threw out the shit engines, gearboxes and diff's that Morris made and fitted the better Austin ones. Remember the lowlight Minor. It was transformed into a magic car with all the A35-A40 running gear.
regards, Dereck
PS we should encourage S U to build carbs for us., or encourage Amal to build their carb with a lubricated slide like the SU. Then we would have a magic carb. It would not wear out the bodies and sliders then. It would have to have an easier system for topping up the dashpots though as they are easy to get at on cars. Lifting the tank off to get at them would be bloody inconvenient.
 
My MGB had two SUs. I have always thought that they were easier to tune than Amals by a significant amount, and Amals were pretty easy!

Dobba99, your trip sounds really good. I wish I was there!
cheers
wakeup
 
mike996 said:
WOW from me too! I have never been able to get much over mid 30s MPG out of my Commando - either the current 850 or the 750 I had back in the day. (oem Amals on both)

But I haven't done a real mileage check in a long time - in fact not since we lived in NY so that was 8 years ago. We're going on a ride tomorrow that will total about 150 miles (with the "new" balanced exh pipes). I'll see how it does on MPG.

I thought I was doing something wrong. A 71 750 with 2 Amals and a 2 gallon tank. Gets me about 30MPG as well. I have to fill up on the way to work and back.
I guess I feel a little better now.
I guess I do push it some. But I like it.
 
I'm sure we have discussed Phoenix SU's before, but anyway I fitted a brand new one from Phoenix quite some years ago to a much warmed up 750 and it gave 83mpg (imp) exactly as Phoenix said it would, I never touched that carb from the day I took it out of the box, I was so impressed with it I bought another and gave it to a friend for his 750, he had the same results as me.
 
A ride out with modern bikes
 
madass140 said:
I'm sure we have discussed Phoenix SU's before, but anyway I fitted a brand new one from Phoenix quite some years ago to a much warmed up 750 and it gave 83mpg (imp) exactly as Phoenix said it would, I never touched that carb from the day I took it out of the box, I was so impressed with it I bought another and gave it to a friend for his 750, he had the same results as me.

That is incredible, unbelievable even.
I had 4 Austin's and would definitely say that the SU is a rock solid little carb. I had 1800's so can confirm that they are the easiest carb to tune that I have ever fiddled with.

How does the SU go performance wise from idle to flat out compared to say single mikuni, twin amals and JS Flatslide?
 
remember the Phoenix carb is the later type with out the separate float bowl and Phoenix obviously spent a lot of time tuning this for Commando, I think they did a version for triumphs as well. I've never seen them used for racing on Nortons but for average road bikes I reckoned they were the best, bugger all maintenance and no leaks,
 
It would be interesting to put it on a rolling road dyno and put it through its paces, with an exhaust gas analyser,
and see how they can achieve such an economical result.

Vacuum operated Bings (BMW) and Keihins (some Jap twins) are similarly reasonably economical,
although drink fuel a bit at higher speeds... ?
 
Dkt26 said:
madass140 said:
...Phoenix SU's before, but anyway I fitted a brand new one from Phoenix quite some years ago to a much warmed up 750 and it gave 83mpg (imp) exactly as Phoenix said it would...

That is incredible, unbelievable even.

Not necessarily. After fitting a single 34mm Mikuni, the old girl gets a consistent 70 mpg (Imp) in mixed riding. Keep in mind that the SU, being a constant velocity carb, can be larger than a conventional carb (for performance's sake), and the mixture closer to the stoichiometric line (for economy's sake). I might have to try one myself!

Nathan
 
MikeM said:
mike996 said:
WOW from me too! I have never been able to get much over mid 30s MPG out of my Commando - either the current 850 or the 750 I had back in the day. (oem Amals on both)

But I haven't done a real mileage check in a long time - in fact not since we lived in NY so that was 8 years ago. We're going on a ride tomorrow that will total about 150 miles (with the "new" balanced exh pipes). I'll see how it does on MPG.

I thought I was doing something wrong. A 71 750 with 2 Amals and a 2 gallon tank. Gets me about 30MPG as well. I have to fill up on the way to work and back.
I guess I feel a little better now.
I guess I do push it some. But I like it.

I'm wondering if something isn't quite right with that low a mileage.
Depending on in town or on the road my 72 750 typically gives between 47 and 56 MPG (US Gallon).
Single Mikuni VM34
 
madass140 said:
I'm sure we have discussed Phoenix SU's before, but anyway I fitted a brand new one from Phoenix quite some years ago to a much warmed up 750 and it gave 83mpg (imp) exactly as Phoenix said it would, I never touched that carb from the day I took it out of the box, I was so impressed with it I bought another and gave it to a friend for his 750, he had the same results as me.

I have got 70 mpg out of twin Amals but think the SU would be better. How does the performance then match up with the single compared to twin Amals. Every one who has single Amals says the performance is down. My current 850 can do 63 mpg driven very slowly, and that is tuned only just above lean.

The man who ran our last rally has an SU on his Commando and he's happy with it.

food for though. I certainly wont buy new Amals when mine are stuffed.
Dereck

I see someone has made a joke out of the fact that I don't have valve stem seals on either of my Commandos. Billy Connelly is funnier.
 
wakeup said:
My MGB had two SUs. I have always thought that they were easier to tune than Amals by a significant amount, and Amals were pretty easy!

Dobba99, your trip sounds really good. I wish I was there!
cheers
wakeup


6 cyl "E TYPES" have 3, early V12 jags had 4
 
I have a Phoenix SU HIF 6 kit, this was installed on my Mk III when I bought her, many of these kits are installed and people have differing experiences, so my 2 cents...

Advantages:
- Fairly simple to set up
- High mpg (66 or so) - giving great range with my Interstate tank

'Disadvantages':
- Heavy throttle action due to the acute angle between the cable socket in the outrigger & carb actuator (I saw an excellent solution to this at the Int'l Rally in Les Settons last year, but I did not get a picture & cannot remember how it was achieved :( ). I used to regularly grease the cable at the outrigger (I once had a cable entertainingly fray whilst riding & jam the throttle open in the outrigger)
- Topping the damper pot, shortage of space between cap & frame meant the tank had to come off to top up (hate that job!), if the dash pot is empty the needle will rattle on the overrun & produce some entertaining popping & banging. I tried 'proper' SU damping oil & also 15/50 - no real difference noted.
- Starting if unused for a day or two was a pita unless the carb was run dry before putting on the centre stand (discussed in another thread here or at NOC website)
- Destruction of standard airbox to fit the 8" oil damped sock airfilter
- 300+ mile range can irritate pillion & cause driver error due to reluctance to stop

After 18k I went back to (new) twin Amals in June 2010 - livelier response & featherweight throttle. If the cost of petrol continues to rise & I can remember/re-discover the throttle fix I may refit the SU (especially after I retire!) . I don't think that twin Amals are that difficult to manage - especially with the assistance of a Colourtune.

I noted that the Wulf I was (for at least some time) fitted with Amals. The Norton 76 seems to have had its SU carb a lttle further back? (the gusset split into 2 to incorporate it) & the throttle cable is angled downwards in a much cleaner line to the actuator. I'd be reluctant tot try & bend mine! The move to SU for the 76 (I'm guessing the Wulf too ) looks to have been for emissions purposes due to it's finer control (see the Bike article: norton-t15430-30.html)

Cheers

Mike
 
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