Cam chain tensioner

[K2-K6]

No and No, blueing is probably single skinned aftermarket headers

Thanks, Bryan. Exhausts are OEM. I never quite understood what causes blueing. A since long deceased racer once told me that when the headers blue, one way or the other, your firing is late. I'd like to learn more on this.

Blueing, the ultimate temperature the exhaust material has reached (research "Kelvin scale" for detail) is affected by combustion temperature, obviously, but with many description not fully aware of what happens to do that.

The cam timing should essentially remain the same (as no adjustment is made to the critical distance in the chain pull run) which wouldn't give a shift in engine operation. If the camchain (very old) gets longer, then the intake valve would close later in crankshaft degree position,  resulting in lower compression ratio dynamic effect. That would tend to cool combustion a little and be opposite of blueing.  Toyota prius for example does this, using an Atkinson cycle engine config. By delaying the intake closed point, the piston coming back up the bore ejects some combustion gases back out the intake port, this lowers the effective compression ratio, gives cooler running, less internal resistance, and quiter combustion.  Generally it won't rev fast though, so they use variable valve timing to facilitate "normal" running as revs climb. Kind of the opposite to Honda V-Tec arrangement, in which they operate at low speed in normal mild timing, then swap to wild camshaft timing at high rpm to give race type performance.

This affects the mechanical component of the combustion cycle, with ignition timing another aspect and overplayed onto anything happening here.

[McCabe-Thiele (Ted)]

I thought Blueing was simply the effects of heat cycles on the Chromed exhuast pipes, dependent on many factors such as ambient air temperature, exhaust gas temperature, exposure to chemicals in the air. Plus the actual design e.g. Single Skin.

It is the case that a lean mixture turns into hotter gases out of the silencer, a rich mixture results in a colder exhuast most noticeable at idle. I'm talking here about using the palm of your hand to measure the heat.

I would be guided by the colour of the spark plugs rather than attaching too much meaning to a blue manifold.

[deltarider]

Thanks gents. Would any of you guys know which model Honda was the first with a self-adjusting camchain?

[DomP]

I thought Blueing was simply the effects of heat cycles on the Chromed exhuast pipes, dependent on many factors such as ambient air temperature, exhaust gas temperature, exposure to chemicals in the air. Plus the actual design e.g. Single Skin.

It is the case that a lean mixture turns into hotter gases out of the silencer, a rich mixture results in a colder exhuast most noticeable at idle. I'm talking here about using the palm of your hand to measure the heat.

I would be guided by the colour of the spark plugs rather than attaching too much meaning to a blue manifold.

I'm not sure I could touch my exhaust at idle, it is a Delkevic stainless system so single skin but still runs very how

[McCabe-Thiele (Ted)]

Not the manifold - you put your palm a few inches away from the tail pipe.

Handy on a  500 as it reflects individual cylinders thus carbs

[DomP]

I've used a temperature gun on it, I get lower temps on the outer two cylinders. 

[McCabe-Thiele (Ted)]

So 1 & 4 are a tad too rich -  try opening  the respective air screw an eighth of a turn out?

That said heat dissipation from the outer cylinders will be better than inner ones so it might be bob on.

Plug colour might be a better guide.

[K2-K6]

The exhaust gas temperature would likely only be reliable for jetting under full load, not at idle. I dont feel you'd need to respond to that in this scenario.

This probably is a topic on it's own rather than in a camchain thread.

The reason to vary idle mixture screws one to another is well established by Honda setup routine though. Theres nothing wrong with doing this.

Effectively, their setup routine specifically tells you to do that on a cylinder by cylinder basis. By turning screw out to go lesser until it fails some firing events tells you where air fuel,parity is for that cylinder. Then it instructs you to turn the screw back in again until you make a 100rpm drop in crank speed.  That sets the individual cylinder to its optimum ..... given the prevailing hardware, fuel used etc.
What this achieves is parity of combustion at the tickover rpm to facilitate smooth running and set the "gain" or slope response for the idle circuit to bring the engine up into running on main jet and needle.
Also,, its the fine detail that people THINK is sole responsibility of carb synchronization routine, which doesn't have the fine resolution to enact this part.

An intrinsic part of production setup from Honda, and why they are rarely a match for idle smoothness post that time.

I've noted before, but this is exactly what modern fuel injection system do to give those ultra stable idle, measuring crank speed and trimming cylinder fuelling to smooth out the peaks. Automated yes, but essentially the same as this old setup.

[deltarider]

[...]
The reason to vary idle mixture screws one to another is well established by Honda setup routine though. Theres nothing wrong with doing this.

Effectively, their setup routine specifically tells you to do that on a cylinder by cylinder basis. By turning screw out to go lesser until it fails some firing events tells you where air fuel,parity is for that cylinder. Then it instructs you to turn the screw back in again until you make a 100rpm drop in crank speed.  That sets the individual cylinder to its optimum ..... given the prevailing hardware, fuel used etc.
What this achieves is parity of combustion at the tickover rpm to facilitate smooth running and set the "gain" or slope response for the idle circuit to bring the engine up into running on main jet and needle.
Also,, its the fine detail that people THINK is sole responsibility of carb synchronization routine, which doesn't have the fine resolution to enact this part.
[,,,]

I wonder if that setup routine was maybe prescribed for twins, where I can understand it can work well. I have my doubts where it concerns our Fours. My CB500 carbs lack acceleration jets and I like to think of the slow jets as auxiliary jets that happen to double as idle jets. Across the pond they still believe in plug chops at idle. From experience I can tell you, it won't work, not on a CB500. Either I have plugs with the ideal color and poor acceleration, or I have a good acceleration and black plugs if I idle too long. Anyway, decades ago, without having read anything on it by Honda, I got the idea myself. In practice it didn't work. Also it is very, very time consuming, I can tell you, as you have to wait at least 20 seconds after each minor adjustment step and there are many steps... I judged the method as typical a theoretical thing from the books. So far I have not seen a video that could convince me. That is: I can't remember I have ever seen it demonstrated on a Four.
If one is lucky to have a 4-4 exhaust, one could try by comparing the sound at the end of each pipe and fine tune the airscrews until each pipe produces the same sound. To avoid the gasses, one could use a rubber hose like a stethoscope. Would be nice if we could arrive at a recording of the right sound for reference. And also which sound indicates a too rich and which sound indicates a too lean setting. I was told experienced professional mechanics, familiar with our models, could do the adjustment by ear.