Paging Mustang...

[Bixxer Bob]

After a bit of a faff getting the parts for this Mikuni monster I finally got it back together.  (It's a BS40 CV)  The bike started 2nd prod, full choke no throttle, and went straight to a nice fast idle, much more willing than before.  It stalled when I opened the throttle but restarted straight away. With a bit of coaxing I got it to rev and it produced a lot of smoke (no real surprise as I'd tried at length to start it before stripping the carb and it was constantly flooding).  Once the smoke cleared it revved freely  and ticked over nicely without choke.

However, it still bogs slightly when opening the throttle before it picks up.  Will this clear with a good thrash or does the idle needle need a tweak? The original setting was 2 full turns but I read it should be 2 1/2....

For what it's worth, what I found on stripping it was the external brass tube going from the float bowl to the cold start cylinder was blocked. The UK Mikuni agent said this was common and due to water running down the choke cable inner and getting in from the top.  Not usually a problem until the bike is left for a few weeks.  The O ring on the idle jet pickup tube was perished (likely cause of the flooding) and the fuel line filter inside the fue -in stub was full of white flakes.

[Mustang]

a CV carb will have a natural tendency for bogging / delay when blipping the throttle under no load as the only thing that makes the slide go up is vaccuum.
The only real way to tell if you have cured it is to RIDE IT ! and even then you could see a small bog / delay when you whack the throttle hard and fast .
It needs to be under load when trying to determine if it's in the ball park or not .

thats why race bikes use flat slide carbs , that the slides are cable actuated .

[Bixxer Bob]

Makes sense, cheers!

[iansoady]

Of course I know nothing about these, but - CD carbs as Mustang says depend on the vacuum to raise the slide. But the rate of rising is controlled by a spring so enriching the mixture (as the airflow was forced to speed up thus sucking more petrol up). The old SU and Strombergs used on cars had oil in the damper tube to further delay this rise and stop the bogging you mention. Playing with springs and different oils gave many happy hours of frustration with Minis and the like.

Do modern CD carbs on bikes have any oil damping (do they indeed even have a spring?)

[JTT]

No oil, but they do have a spring.

[Bixxer Bob]

Ah I remember now,  I had twin Strombergs on my old Imp when I was a lad.  We'll see how the Aprillia runs on the road.

It's not particularly old but quite rare as they didn't make many or for long so here's a pic:



It's got the Rotax 650cc engine with Aprillia's own 5-valve head.  I'm not sure if I like it or not to be honest, I kindof do, but wouldn't want anyone I know to see me on it.

[Sin_Tiger]

Know what you mean. Like looking at some really hot woman in a club and liking what you see, you just wouldn't walk around Tesco's with it and definitely wouldn't want to pay the salon and shopping bills later 

[Bixxer Bob]

Know what you mean. Like looking at some really hot woman in a club and liking what you see, you just wouldn't walk around Tesco's with it and definitely wouldn't want to pay the salon and shopping bills later 

Good analogy 

It.s the work of french designer Phillippe Stark and carries his logo. It was more of a failed fashion exercise than a serious motorcycle, around the time of the early Ducati Monsters.

[Chris Canning]

More like looking at the Hunch Back of Notre Dame,what a bloody horror,and I'm under stating my thoughts at that!!! and no doubt worth big bucks.

[metalguru]

BB going back a few to the pilot jet adjustment, the 2-2 1/2 turns out is a guide as the best adjustment is attained at normal working temp and the smoothest idle after carbs are balanced. If you have privvy to an inductive pick-up rev counter then set for the highest which will be correct mixture as rev counter accuracy is usually in tens. Have had them out as far as 3-4 turns especially on the old aircooled vtwin Yams to rid the stutter at just off idle. Then of course fit a Dynojet kit etc and any references go straight out of the window.

       

[Bixxer Bob]

I hope it doesn't need touching as it's a bugger to get at.  Only one carb though so no balancing to do.

@ Chris C:  Seeing as how you love it so much here's the history taken from REAL CLASSIC.CO.UK  :

Starck Naked in London 

Aprilia's Moto 6.5 was designed to be different, but does the Philippe Starck styled form detract from the Rotax powered function? Enter Paul Miles on his Marmite motorcycle...

London, the home of hustle and bustle, style and passion and, in 1995, Yuppies.

Imagine that you were an up and coming motorcycle manufacturer, Italian of course, wanting to make your mark, differentiate yourself from all the other bike producers. What market to go for? What about all those young guys in the cities, cash rich and time poor, willing and able to pay for something stylish or new? If they wanted speed they'd drive their Porsches; no, what they want is something funky and nippy for whizzing about town on. These guys buy £1000 coffee machines and £5000 sofas from that French designer, Philippe Starck, so who can we get to... Hang on, I've got it!

Philippe Starck is one of the modern world's great jobbing designers. He's designed everything from orange juicers to houses and shot to worldwide fame when he redesigned president Mitterand's apartments in the 80's. Along with Ross Lovegrove (small matter of the Sony Walkman and the Audi TT), maybe, he can lay claim to be the designer of the 20th century. He was tasked by Aprilia in the early nineties to produce a motorcycle to appeal to the new generation of slick city dwellers. Essentially, he was told 'you draw it, starting from a blank sheet of paper and we'll build it' with minimal interference from the factory. The result was the extraordinary Moto 6.5 Starck.




1996 Aprilia Moto 6.5


The outline brief was, perhaps: A very stylish and futuristic, naked city-bike design, that especially appeals to current non-motorcyclists; it must not be seen as threatening or overly aggressive. Easy to clean and maintain-the likely owners will be mechanically unsympathetic. Narrow, for negotiating city traffic, soft suspension for the potholed roads, comfortable riding position, with the acceptance that the riders might not wear protective clothing.

Aprilia already had the motor; their Rotax derived 650cc, five valve single was good for 40BHP at the rear wheel and around 115mph. The rest was up to the Frenchman, and blimey, did he deliver.


Launched with great fanfare, they even managed to rope in 'he of giant daisy' fame, Peter Gabriel, to pretend he was a hard-core, umm, city biker type, when, in reality, he was too busy playing games without frontiers to go gadding about on some weirdo bike, even if it was up Solsbury Hill.

First impressions of the bike are of overwhelming greyness; excepting the large mirrors, there is no chrome or polished alloy anywhere. Everything is paint or brushed finish, apart from the giant, egg-shaped, orange tank, of course!

It's impossible to ignore the tank; it's in your eye-line from every angle, dominating the view. When you look more carefully, you see that the curve of the seat, the curve of the frame rails and of the exhaust, as well as the mudguard, all match the tank, it always comes back to that petrol tank, it's the nexus of the design. Anything not thus curved is small, like the indicators.




The alloy rims and stainless spokes carried large tyres with a high profile, at Starck's insistence. These tyres came in for considerable criticism when the bike was new as the handling was deemed to be compromised, but they looked so... right. There's a suitably curvy rear carrier and you could even buy curvy luggage to fit the rack, though it didn't hold much, if you were going away for the weekend you'd take the Porsche, after all.

Needless to say, it didn't sell. The yuppies largely ignored the nasty, smelly, motorbike and 'proper' bikers laughed at its twee nature. Fifteen years on, the few that were sold are mostly dead, crashed many times and un-repairable due to the lack of available body panels. At one stage you could buy a scabrous Starck for under a grand. Not any more, though. They are now collectable and recognised as a design classic, irrespective of their functionality as a motorcycle.


How does it stack up as a motorcycle though? Essentially, despite all the design flourishes, that's what interests us as riders.

Well, it's reasonably tall, although about 2" lower than the similarly powered Pegaso trailie, and very narrow; you get a great view of the road, and at 150KG, it feels very light and chuckable. The motor starts on the button and whirrs away in almost complete silence, the fierce-looking twin 'straight through' pipes have, in fact, got a giant collector box under the engine, giving a quiet, city-friendly, ride. The motor is very smooth and punchy and it whizzes up to 90mph in a jiffy and down again just as well, the Brembo brakes (of course) doing a fine job of retardation.




The suspension is long travel and s-o-f-t, great around town, as it's RealPothole ready, but it can get a bit squirrely when pressing on down a country lane. Heavier oil in the forks and a twiddle of the monoshock preload should help a bit, though. The drive chain is adjusted using large eccentric cams, a doddle, although no mainstand is fitted; perhaps using a centrestand whilst wearing Gucci loafers proved too difficult. Most consumables are off the shelf, it's only the bodywork that's made from unobtanium. The clocks are simple and, of course, curved, with the tiny idiot light cluster being virtually unreadable in daylight.




This particular example hails from 1996 and has only covered 12,000 miles. I found it deep in the classified section of Realclassic magazine, the fount of all great and weird bikes. It's stood the test of time remarkably well, with almost no corrosion or faded paint, a testament to Starck's chrome-free commitment. The only parts that look a little grubby are the control cables and grips, most everything is, of course, grey and it's yellowed a bit with age. The only black bits on the bike are the tyres, footrest rubbers and brake hoses. New Avon Roadrider tyres have been fitted which still give the aesthetic look of the original, but have a much more modern profile and grip characteristics.

I can jump on it and ride into central London without fuss or bother, in complete comfort, or go for a quick 50 mile blast. It's fast enough, has great brakes, rides like a well-sorted trailie and looks fantastic. The only problem I've found is a dodgy bulb holder in one of the indicator stalks. Sheesh-rubbish Italian build quality strikes again, it's barely fourteen years old and already it's gone wrong, some might say. Even the standard toolkit proved ideal for adjusting the rear chain, easily accomplished in about three minutes. Blimey.


It's too easy to dismiss it simply as a cynical styling exercise, but where are most trail-style bikes used? On the tarmac, of course, complete with their too-long and soft fork travel, marginal brakes, super wide handlebars and unsuitable tyres. And what about Harley Davidson? The concept of the endless road reels the punters in, but mostly they get used for a thirty mile run on cloudless Sundays. The Starck was designed as a city bike for city streets. The nearest I've come to it in a modern bike is the BMW F650 Scarver, which offers a very similar experience, but looks like it was designed by a German engineer, sadly.

Every time you look at the Starck a new detail reveals itself, it's a ground-up concept that works. When it arrived I was equivocal about it, both as concept and motorcycle. Now, I'm sold. My website designer, a biker, thinks it's one of the great design concepts, irrespective of the fact it's a motorcycle, and wants it for his dining room, yet my wife loathes it! A real Marmite bike, if you like. Style and substance, what more could you ask for?

Starck naked in London? Oh yes, most days!

[metalguru]

Bought a right angle drive screwdriver that is bevel gear driven, think they are still available at about £40. Will try to find a retailer later and they get to most pilots.

Nice looking bike by the way, the quote is right, the more you look the more you see.



EDIT
OK so its gone up a bit but here you are :-   http://www.ebay.co.uk/itm/Motorcycle-90-deg-Angle-Driver-Carb-Tool-Boxed-Screwdriver-Set-/370653028475?pt=UK_Motorcycle_Parts&hash=item564ca4607b

[Bixxer Bob]

'KIN HOW MUCH????

Seriously though, thanks for the pointer, but I don't think it'll get enough use to warrant the cost.  I'll cobble something up if I need to... we'll see.

[Chris Canning]

Nice looking bike by the way

Should have gone to Spec Savers 

[metalguru]

Nice looking bike by the way

Should have gone to Spec Savers 

And coming from a man openly admitting ownership of a MK1 Goldwing.