Archive for January 2011

XS650: Inbuilt Limitations   Leave a comment

When you talk with people who play with these engines, they will mostly tell you how solid they are. How destressed and strong they are built.

To a degree they’re correct.

This was the first 4 stroke motor built by Yamaha. So they were careful. Didn’t want expensive mistakes. The heritage was of course German. It was pretty solid to begin with. Add a little nervous over-engineering and you get the XS1. Built as a street engine. It didn’t have years of racing development behind it.

Many of the ideas were reworked into their second 4 stroke. The XT500. And look where the French took that. Bet Yamaha considered making Olivier an honoraray Japanese.

The fascination for Motocross and Enduro killed Yamahas’ interest in Flattracking while they were at the top. A real shame for Shell Thuet. Also for Bob Trigg.

The XS1 was immediately improved. Clutch. Forks. Crank. Brakes. Later, Percy Tait showed how to improve the frame geometry.

With some improvements the motor basically stayed the same for years.

XS1s make good restoration projects, although the heads breathe somewhat better. 447s make good café racer bases. And Specials lend themselves, with their layed forward rear geometry, to choppers and bobbers. Everyone’s happy.

Restorers will debate the interchangeability and logic of XS1 headlight bracketry or fork internals vs XS1B or XS1F and XS2. Corner carvers will relish the Standard frames improvements. Commuters the electric start. Easy riders the lower-slung specials. Sidecrossers and hillclimbers the simplicity and grunt.

They will all see strengths and weaknesses depending on the design problems they meet and the level of customising they do.

The further you go the closer to the limitations you come. The machines’. The machinists’. The mechanics’. The riders’. And your pockets’.

The problem is that, unlike global finance, the trickle down effect actually works in the real world of mechanics. Any changes you make here directly effect how that there works. Every action has an opposite and equal reaction.

In reality the reaction can be plural and the effects cummulativly overwhelming.

Means, you start playing with the motor, increasing the cubes, playing with the squish zone, allowing her to breathe, changing the timing and you begin experiencing the limitations.

Same with any system in balance.

Talk to the big cube and torque blokes and they tell you head design and the crank centre pin are the ultimate limiting factors. No matter what you do to the rest-it’s that pin that goes.  Some talk about converting the cases to take conventional bearings and running high pressure oiling. Or machining 1 piece auto style cranks and 2 piece conrods.

It’s not going to change the fact that they simply don’t like being shifted over 7500. The little end stretches. Any piston pin play and you have problems.

Fine. What gives next? Cylinder stud anchor points in the crankcase. Aluminium.

Liner thicknesses. Pistons.

Increase cubic capacity? RPM? You’re talking air. Has to come from somewhere. And go there too. Carburetion. Exhaust. Only as good as the head.

Also here the talk is porting. Cylinder centres and stud patterns. Machining existing DOHC heads to fit? Or making your own.

Got good flow? How to get it to the rear wheel? In a way you can control it?


1 .. 8 valve head ... wim mellendijk

8 valve head … wim mellendijk



And frame geometry.

None of this is new. Each pushes the envelope. Each tests the limits of it’s partners in crime. All is linked…ommmmmmm

Bud Aksland talked about..

‘…rephasing cranks, different firing orders, hundreds of valve, cam piston crown profiles, welded up ports,…the list was endless…the basic … was a stock set up with a weighted crank…the stock head casting was the limiting factor…is why the OU-72 was commissioned…purpose-designed casting with more favourable valve angles etc.’

‘…it is an engine with built-in performance limitations and if you are going to be successful in your attempt to extract more user-friendly power, it will have to be done with a systematic, integrated manner.’

Kenny Roberts talks about it too.

‘…Accepting the deal from Yamaha meant we had good roadracing bikes —real roadracers built by Yamaha.

But the dirttrack bikes weren’t so good. We had to make do with Yamaha’s XS650 twin, a steetbike, as the basis for a dirttrack racer…

…we struggled with the XS650 that first year. Still, I earned enough points that year to move from junior to expert.

In our struggles with the XS650, we too often resorted to using pistons from here and a cam from there and these valves trying to make the bike fast. We also managed to blow it up a lot!

…in ’72 Yamaha decided to get serious and added Shell Thuet to the team. Shell was an established motorcycle dealer in Los Angeles; he was very experienced, and he knew how to build a racebike. Like all good tuners, Shell knew how to make all the parts work together. He made sure to build reliability in before trying to build horsepower. Some things never change. This is still the best approach to building a competitive racebike’

Posted January 24, 2011 by xscafe in Frame - Handling, Motor - Breathing, Motor - Head

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XS650: Pod Air Filters   3 comments

I lightened down my bike considerably. All the electrics went. Run batteryless. Removed the air-boxes. Left the whole section under the seat empty.

Looks cool. No good for the motor.

Had a pair of el-cheapo pods lying around. More or less the right diameter, according to the label. After fitting I decided I could do better:


1 .. now how are you supposed to get a good seal there? ... also see the cracking along the edges - this was new out of the bag!!

now how are you supposed to get a good seal there? … also see the cracking along the edges – this was new out of the bag!!


2 .. big inner lip ... everything restricted ... diaphragm vacuum port at the top: pilot air jet-lower left: main and mid range air jet-lower right: bowl vents in the middle

big inner lip … everything restricted … diaphragm vacuum port at the top: pilot air jet-lower left: main and mid range air jet-lower right: bowl vents in the middle


3 .. these filters had never been used

these filters had never been used


4 .. was then given, under protest, a set of these

was then given, under protest, a set of these


5 .. larger surface area

larger surface area


6 .. no restricting step

no restricting step


7 .. very thin walled ... rubber may not hold up esp. with no support...wonder how long it will the rubber ethanol proof?

very thin walled … rubber may not hold up esp. with no support … wonder how long it will last … is the rubber ethanol proof?


  • very thin
  • where-ever you look the filter wants to break out of the rubber
  • see the large hole in the flange lip? WTF?
  • strong enough to hang unsupported?
  • ethanol proof?

Not an optimal solution. But heaps better. Will have a look around for a K n N to compare.

When I think about it I guess I should add here that pods generally increase engine breathing capacity. The immediate effect is to lean the carb mix. More air, less gas. Pistons and valves don’t like this. Get a little intimate with your carbs. Odds are you may have to massage your jetting.

Reading will tell you. Chop those plugs.

XS650: What Could Have Been   Leave a comment

I don’t require a bike to be clean. Mine mostly aren’t. I do require the lines to be though. And the feel. That must be right.

Many of my bikes have been what most might call rats. Now I don’t take that negatively. After all, rats fulfil their niche conditions perfectly. Evolutionary survivors.


1 .. a prime example of what was being produced in the mid 70s...this 6T chop of my cousins took out the cold kiwi hill climb in 1977 when many specialised bikes failed

a prime example of what was being produced in the mid 70s…this 6T chop of my cousins took out the cold kiwi hill climb in 1977 when many specialised bikes failed


If form and function are observed, a bike is not supposed to remain clean.

This is one of the things I like about the XS650. And not just me. This is a machine that simply wont die. A ghost returning to haunt Yamaha.

3 clean platforms. None perfect. All with recogniseable soul.

You met Bob a while ago. He helped create the Ténéré 650 prototype. He came from Norton, NVT. Did little jobs for Yamaha.

“We were trying to create extra business. The British motorcycling industry was sort of collapsing, and tried to generate money by doing engineering contracts for other companies. We did several contracts for Yamaha while I was technical director at Norton. Yamaha wasn’t the big international company it is now, and they did not know about Europe as they do now.”

Development of the HL500.


2 .. HL500 .. cool singles

HL500 .. cool singles


“At Norton we did the HL500 motocross bike with the TT500 engine. We developed the chassis, it was the first one with an aluminium swingarm. It was a very exclusive bike, only 300 units were produced.”

And the NVT650.


3 ... NVT650

.. NVT650 … often called the Ascot TT, according to Ludy Beumer from Yamaha Netherlands ‘The Amercano’s (YMUS) had absolutely nothing to do with this project.’ Bob Trigg himself said that the american flat trackers – ascot – was only the design concept


“Also we did a good styling concept for the XS650, styled as an American flat-tracker, the Ascot TT. I still have the bike, it still works great, it’s a real pure motorcycle. When I ride it, people still ask me where they can buy it.”

I’m sure I’ve seen this bike. In the French Alps. Doing what it was designed to do. Leave me in the dust.

Halco, I believe, used to knock these off. Even caught some of the magic.

It’s not perfect. But. Bob is right. It would have sold.

Too bad the French were still to learn their rally marketing lessons.

What could have been.

…nicely written-up in Classic Bike Dec 1996 p102-5…

XS650TT Bob Trigg Ascot TT

Posted January 23, 2011 by xscafe in Frame - Design, Frame - Handling, XS Pics

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XS650: Spam Hits   Leave a comment

WordPress doesn’t seem to want to do anything about the spam hits I am receiving.

I don’t like this.

Can anyone point me to a blog site that has an anti spam policy?

Posted January 22, 2011 by xscafe in Uncategorized

XS650: Tanks Tin and Tone   Leave a comment

I found this site. Deals with Vintage Japanese Motorcycle Painting.

Marbles Motors.

Great if you are looking for tank shapes. Colours in use.


T1 .. XS1 tank

XS1 tank



T2 .. Subtle




Looks can be deceiving.  Graphics are very subtle.
Base is orion silver, followed by gold graphics. Some platinum metallic. Then 3 coats of pagen gold candy and 4 of clear.

Posted January 22, 2011 by xscafe in Frame - Design, Frame - Tanks n Tin, XS Pics

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XS650: Cat Time   Leave a comment

Time. Strange thing, Time.

For many it marches.

Tic. Toc. Tic. Toc. Tic…….

Clockwatchers. You all know one. Tic. Tic.

They always complain about time speeding up. Time flies.

I reckon time flies for them because they’ve done nothing worth remembering. There’s no record of that time memorable enough to remember. Their record of memorable events is short. Collected, Flicked through, Animated. All over in a blink. A flash in the pan.

Life in the fast lane.

dum dee doo

Go out there. Wind in your face. Do it. Live the moments. Collect the memories.

2 things happen.

  • Time doesn’t concern you
  • Your collection becomes so big your perceived time slows.

Cats know this. You watch.

They always land on their feet. The only cat I’ve seen miss was out to lunch beforehand.

9 lives? I reckon not. They feel time differently. Closer to it they are.

It flows. Depending on your perception.  You all know this. Intuitively. You’ve even felt it. Moments of danger. Intense embarrassment. Connecting with that special person.

You can do this. Any time you want.

You are energy. So is time. Different flavours. Same Eis.

Same. Same. But different.

You’re connected. Like cats. Just not so close.

We learn to get closer in Kung-fu. Similarly Tai Ch’i and Yoga etc. Your connectedness feels disturbances at a finer level. Sub-consciously. And the responses are amplified.

Most people near the top in their field probably experience this too. Many unaware.

Motorcyclists rely on this. Daily.

Throttle response. Shifting. Body too. Balance. Split seconds.

Cat-time seconds.

The faster. The tighter. The riskier the riding. The closer to time you get.

Cat time.

650’s rule.

Posted January 21, 2011 by xscafe in Frame - Design, Frame - Handling

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XS650: Ténéré   Leave a comment

What do this

1 .. SR500 prototype .. 1973 .. Shiro Nakamura

SR500 prototype .. 1973 .. Shiro Nakamura


And this


2 .. 2011 Super Ténéré 1200

2011 Super Ténéré 1200


Have in common?

Ask Bob Trigg. He can tell you.

“We constructed a bike with the twin engine as an example for Japan, and presented the target concept for such a model. That was the birth of the Super Ténéré. We requested a big capacity 750/900cc twin with big torque feeling, and with a modern engine: the 45 degree engine layout, as the Genesis engine of the FZ750 had.”

“Our target was to launch a Paris-Dakar OW factory racer, then the Super Ténéré, and then a new Street bike with the same engine. That became the TDM 850, an alternative touring bike developed to be the best bike in the Alps.”


3 .. prototype, a Ténéré 600 with an XS650 twin engine mounted in it

prototype, a Ténéré 600 with an XS650 twin engine mounted in it


The humble XT500. Took out the inaugural Paris Dakar 1979. The French went mad. Vive le Bleu

4 .. '79 Paris-Dakar .. 1st 2nd

’79 Paris-Dakar .. 1st 2nd


1979. 1st. 2nd. 8th. 12th.

1980. 1st. 2nd, 3rd. 4th. 8th. 9th. 11th. 12th.

1981. 2nd. 3rd….took out 11 of the first 31.

1982  saw the XT550. 4th. 5th. 10th…..11 from the first 33.

1983 XT600. 4th. 5th. 7th. 8th. 15th. 23rd. 24th.

1984 XT600. 6th. 7th. 9th. 11th. 14-17th….13 from 33.


05 .. 81 XT500 Paris-Dakar

81 XT500 Paris-Dakar


Bob Trigg says:

“Also in offroad we were trying to get away from the 2-stroke image. A lot of efforts went into developing the XT/TT 600 line-up, we were also entering the Dakar rallye and that was very popular. Sonauto, the French importer, asked for a production version of the race bike so we also introduced the Ténéré.”

“Later it became clear that a single cylinder could not win the Paris Dakar anymore, and we considered other engine developments. Even a 4-cylinder was an option, but it was a problem to get enough grip and traction for offroad use. So we made a big-bang engine, firing like a twin. But in the end nobody liked it, a 4-cylinder was supposed to be smooth and to have the typical 4-cylinder sound, that was the in-thing of those times.”

Imagine that.

Posted January 21, 2011 by xscafe in Frame - Design, XS Pics

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