A week or so ago CM wrote asking about operating temp differences left and right. Why does the rhs run hotter?

 

 

xsjohns, rip, engine temp recording … with cooler … left and right can run up to 30° or so difference

 

 

I’ve been out of town. Away from my computer. Exiled. Disconnected. But not deleted. Basically this is the answer I sent him.

Over the years I’ve heard many postulate. From aerodynamics to exhaust placement.

When you look at the engine design you see all the mechanical parts are focused to the right. As is oil flow.

Hot oil is sucked up through the pump. Slowed at the filter.

Mechanical action from the tacho, oil pump, primary and clutch all add frictional heat.

Aluminium is a good conductor. Heat gravitating upwards meets that from the combustion chamber and exhaust ports.

To the left we have the generator. In an air cell. Dry. Different thermal properties.

Allows the left to act more efficiently and effectively as a heat sink.

When Yamaha built the carbs they did so symmetrically. Jetting specs both the same. Each operating in different thermal environments. Built in imbalance. With appropriate feedback loops.

If you have adjustable needles it is possible to richen the right hand carb by raising the needle.

 

 

lowering the clip raises the needle … enrichening the mix

 

 

XSJohn, rip, ground needles with different tapers as a set. Left and Right. The canadian needles apparently are similar. Replace needle jets and jet needles together as a pair.

 

 

xsjohn, rip … on his needles … no grooves here, his production needles were grooved

 

John also built wings or foils to deflect airflow over the cylinders.

 

 

xsjohn’s wings … notice the deflector under the lower clamp

 

 

Others install oil coolers.

 

 

remote filter and cooler … so positioned the cooler will reduce air flow over the head

 

 

heidens side filter-cooler

 

 

Today there are many diagnostic techniques. Years ago I had an interesting conversation over too many beers with an Australian Naval NCO. Have never been fond of military types. Too rigid. Thinking actively suppressed. Later I was to learn the corporate world is, in theory, no different. In practise, a lot worse. Establishment meeting punk – the shock was mutual. He was a vibration analyst. Spent his time listening to machines sing. No different really to listening to your motor through a long solid screwdriver. He had a lot to say about the internal workings of Australia’s navy.

I would like to see a series of  Infra Red pictures of an XS650 motor running. Done in a resolution capable of  differentiating temp gradients within the 80-300° range. You would see some definite nodes on the right and fronts associated with temp assymmetry.

I come from the southern hemisphere. Live in the north. Apart from north and south there are other differences too. Here they drive on the wrong side. When you pull the bath plug, flush the toilet, water runs anticlockwise-the coriolis effect. I wonder what this does to other physical gradients .

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:

 

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!!

 

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

 

these filters had never been used

 

was then given, under protest, a set of these

 

larger surface area

 

no restricting step

 

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.