Terry

That is good work; I have done the same on my ST1300 which shares similar components. I hope your brake now behaves itself. I found the rebleeding process to be tedious specifically flushing air from the SMC. In the end I enlisted a helper (my wife) and between us we pressed the brake lever and held it, pressed the SMC in and held it, and released at the PCV. Then released and pressed the brake in and held, which pushes the SMC back to full and repeated the process. Ended up with a great lever feel which I could not get with conventional bleeding.

I can't quite match the vintage, but here we are in 1982, me and my mighty CB125T; two tiny pistons frantically going nowhere! 12000rpm redline! The T did not stand for torque however. This was my first motorcycle and started my love afair with Honda.

Looks like rapid unplanned disassembly to me.

If there is decent airflow through the radiator then the bike should sit at/near the thermostat opening point of 78-80C or 176F irrespective of the ambient temperature. When you get stuck in traffic (no air passing through the radiator) the temperature will rise to around 100 (212) and should cycle up/down as the fans switch on off. To get higher than that would suggest maybe the fans don't work or the thermostat is stuck. Let's assume the cooling system is full and the reservoir has a decent volume as well (you checked that, right?). If the radiator stays cold when the engine starts and then suddenly gets too hot to touch around 176, the thermostat probably works. If the radiator gently warms up as soon as the engine starts, the thermostat is probably jammed half-open. If the radiator never gets hot, the thermostat is probably jammed shut. Check the fan switches itself on around 212F and off a few degrees below that. Some have altered the fan wiring to put a manual bypass switch in place, so if you are going to get mired in traffic you can start the fan earlier.

This is nearly 41 years ago...before the invention of colour! Not sure why I'm looking so stern...my girlfriend took the photo. It is easy to see why I never made it into the movies too. This was the bike that I borrowed for a test-ride from the dealership I worked part-time at, and dropped at over 100mph discovering just how powerful those front brakes were in a pre-ABS world...this is the "after" photo, after I purchased and repaired the thing. Maybe I was thinking about how stupid I was (and to be fair, still am).

I will stay in my lane and comment on what I know about, and leave the electrickery to Grum. The oily stuff in the airbox is normal, just a bit of oil mist blown from all the wrhirling bits in the crankcase up through the breather hose to the airbox. The white stuff will be some condensation that has made it to the airbox. If the bike hasn't been run for a while this might be expected. If the bike has been running regularly then this would be unusual. The odd man out starter valve is the non-adjustable reference valve. The other three get adjusted to match this one. The SV's control the flow of air into the motor at idle; more air = faster idle. The SVs are moved by the wax unit when the engine is cold to give a faster idle when first started. The SV positions are also controlled by the idle adjuster screw when the engine is hot.

I'm sure he'd be up for an all expenses paid trip to the US with his multimeter.

You are a gem Graham. Top (and detailed!) advice.

Infinitely high resistance for the temperature sender = a broken (or disconnected) wire.

Rich running might be caused by the engine coolant temperature sensor or the fuel pressure regulator. The ECT has two circuits, one feeds the dash readout and the other feeds to the ECM. If the ECM thinks the engine is cold, it richens the mixture. There are some resistance/temperature checks that can be done to determine the health of the sensor. The FPR has a vacuum connection to the intake tract; when the intake vacuum increases it reduces the fuel pressure (so the fuel pressure relative to the manifold pressure stays constant). If the FPR diaphragm has a pinhole, or the vacuum hose connection does not hold vacuum, the fuel pressure will be higher than intended and the engine will run richer. If the diaphragm has a pinhole, raw fuel can be pulled into the vacuum hose as well. K&N filters have been the cause of poor running elsewhere (VTR1000F) and it might be worth trying with an original or pattern filter. However I would have thought a combination of a freer flowing inake and exhaust would be more likely to produce a lean mixture. Does your bike still have the O2 sensors in the headers; if not (and if no Power Commander or similar is present) this might result in the ECM trying to adjust the mixture and lead to poor running.

Too much spam? No such thing. https://youtu.be/anwy2MPT5RE

If the wax unit is not receiving coolant then it will keep the starter valves open more than you want when the rest of the engine is hot and give the excessive idle. Either an air lock or possibly the "cleaning" process has moved some crud in the small water hose and caused a blockage. My view is that a blockage is the most likely cause of a "wax unit failure" rather than any mechanical fault with the unit itself.

Very thin, fuel-smelling oil and lots of it would indicate a leaking fuel injector. The tank is quite happy to gravity feed through the pump to the fuel rail, and if an injector is stuck open it can allow a quantity of fuel to drain into a cylinder, past the rings and into the crankcase. Good thing that you changed that out promptly, bad things can happen with so much fluid in the crankcase, and you likely have ejected some excess oil up to the airbox through the crankcase breather, which might explain a bit of smoke. Open the airbox up and take a look, a little oil mist is normal but not much in liquid form.

I have done that myself on my 800; tried to install the pads while the calliper was mounted to the disc and managed to catch the edge of the pad spring during installation. Made for a weird brake as the spring would push the pad off the disc so there was lots of travel until the brake was pumped up fully. I would just straighten the pad spring out.

Well the brakes are not going to be the cause. Ever seen a bike with single front disc? More likely a worn tyre, maybe misaligned forks or perhaps you aren't sitting straight on the bike.

I also wondered what would happen if you used the non-VTEC buckets and valves in the VTEC positions so 16 valve operation is constant. It appears the cam lobes are the same on both VTEC and not VTEC valves. Probably not worth the effort.

VTEC on the bikes activates 4 valves per cylinder at higher revs and 2 vavlves at lower revs. I think the earliest iteration had asplit forked rockers and a locking pin slid across to lock the two valves together. The VFR system stuck with the shim under bucket direct valve actuation of earlier models but the VTEC valves have special buckets that also use a locking pin activated by hydraulic pressure to connect to the valve stem. It sounds terrifying but clearly isn't as mechanically deadly as I would have thought.

Well that takes the cake for a comprehensive answer Cogswell! Well done!

I think you'll find there are some internal gearbox ratio differences between the 5th and the 6th. The crank is obviously different (gear vs chain sprocket for the cams) but AFAIK the bore and stroke are the same (so maybe rods and pistons?), and I assume the lower crankcase is too. I suspect the alternators are different. I know at least one person has swapped a 5th gen engine into the 6th frame so I presume the engne mounts are the same. So aside from the crank, upper case/cylinders, heads, gearbox, alternator...its all the same? Probably doesn't leave much.

There's a balance involved between the starter valves, the idle stop screw and the wax unit nut. If you mess with one, you may mess up the other inadvertantly. Another member unwisely messed with the "unadjustable" starter valve screw (#4?) when synching the throttle bodies and closed those down more than they should be (but they were all nicely in balance 🙂). That resulted in the idle stop screw having to be wound in in much more than usual to get the warm idle correct to hold the starter valves open enough. And that resulted in the starter valve opening mechanism being held unnaturally open when the engine was cold to the point where the wax unit wasn't adding any cold opening to the SVs at all. Which means the cold start idle speed was unpleasantly low. If you can verify that the wax unit is changing it's length as the coolant temperature is changing but just not by enough to lift the SVs open when cold, then I would have a crack at changing the unadjustable nut, but at the very least mark the "factory" position before you start so if/when it all goes tits-up, you can return to the original setting.

The oil leak is quite impressive but also looks to have been ongoing for a while so probably not major, just persistant. I would start looking at the oil filter in that area, the other spot would be the cam cover gaskets; these can fall out of place when being refitted, or the half-moons didn't get any sealant as they should, or the gasket might not be clamped enough to seal. Don't be tempted just to crank more torque onto the hold-down bolts for these, they thread into the head casting and that easily snaps. You might need to replace the rubber washers under the hold-down bolts as these compress with age and don't apply enough clamping force to the gasket. Another possibility in the same area is the gasket around the spark plug tunnel if that is not seated properly, oil can leak into the plug well and then out of drains under the heads. Not sure there is any other common oil leak point, but given you are in the UK with salted roads, corrosion on the oil cooler lines is something to consider.

The spare wires look like the clutch switch wire, and I see that you don't have the original clutch master so that would be why. The clutch switch is usually needed if you want to start the bike in gear.

I don't have the patience to read back very far. Is the eccentric adjuster for the rear wheel flipped over?

Can you take the gauge faces that you have removed from the VM and scan them and send the scans to a label maker to print off in black/orange? There's also a number of suppliers of alternate gauge faces on the internet that might do the same work.

I don't recall hearing of any issues with the CB750 Hornet that was recently released with the same motor. Maybe your "interesting" climate has had an effect on a stationary bike engine that has not seen any running? I was thinking that if you cooled the system down a lot that would pull extra coolant out of the reservoir, and then when "normal" temperatures were applied the coolant expands and pressurises the system but not with the engine running and the ceramic seal wetted up? I don't live anywhere that cold so this is pure speculation on my part.