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[2cvandy]

Hopefully, if I followed the instructions correctly, you should be looking at a photo of the oxygen sensor lead on my EFI Electra. The bike is running a replacement silencer from Mr H without baffles. It runs well, as far as I can tell, having not ridden any other bullet since I owned an Indian 350 in the early 90s. But it pulls strongly, accelerates briskly if asked, pulls up hills in 5th gear without complaint, cruises happily with 60mph on the clock (I'm guessing around 55mph?) and will accelerate from there in 5th gear for overtakes quite quickly. As far as I can tell it's returning around 70 - 75 mpg at the same time, although the downpipe is a lovely shade of blue so I'm assuming it's running weak? My question is this, the chap I bought it from tells me that the dealer who fitted the silencer for him did this to the oxygen sensor wiring because he said it would run better this way. So what exactly has been done? I'm assuming these are wires pushed in to complete a circuit? Although I've not pulled them out yet to see, maybe they're just keeping the cr*p out?

[RayBeech]

My efi has this as part of the Power Commander kit, the actual sensor in the pipe is replaced by a blanking bung.

[jefrs]

The bluing is what I got when I fitted H's '50s Free-Flow' system. Fitting the PCv, which includes that O2 sensor bypass resistor, cured the bluing. So I'm pretty sure H sell the thing separately as well as the blanking plug for the hole in the exhaust pipe when you remove the O2/Lambda sensor. I gather that unless you go the whole hog and fit a K&N, you don't need the PCv but the O2 bypass resistor is advisable so it runs in 'closed loop' and not so weak and hence hot at the exhaust down pipe.

The O2 sensor is supposed to self-adjust for changes to the exhaust system but if you have bluing it has not done enough. It also takes at least, at least 90 seconds to get up to operating temperature before it does anything at all, and then it's only a narrow-band job.



Do check for air leak between head and pipe because the cement biscuit seal is not very good; if you can turn the pipe with the silencer off then it's not tight. An air leak can also make the pipe too hot. Easy to disturb the seal when fitting a new silencer.






Judging by traffic speed and by driving the car with an accurate speedo in the same traffic, and the Gatsos, the speedo on the RE is not far out: 30mph indicated is 30mph, and judging by the way it quickly catches up with cars doing 60 (because that's what they do on open NSL roads hereabouts) 60mph indicated is probably more like 60+ than 55.

[2cvandy]

So Ray, from what you say my bike may have a power commander fitted. Can you tell me what that looks like and where it might be situated? I'll have a look and see if it has one. It could be of course that the blueing was caused before the pipe was changed, if that was the case would the blue eventually disappear? or is it permanent? My bike still has the sensor in the pipe but of course it's not connected. I'll check for an air leak too Jefrs, because now you mention it I do occasionally get a back fire slowing downhill on a closed throttle, so that's a distinct possibility.

[jefrs]

If you have a Power Commander 5 (PCv) you will have doubled-up connectors at various places, easiest to find being the injector, with a black 'mesh' covered loom leading to the PCv. Mine is in the electrics box, they can be under the seat or elsewhere, you're looking for a small black box size of cigarette pack with red on the label. If it came from H it would have the O2 Bypass resistor plug and the pipe blanking as part of the kit, plus their bespoke Bullet mapping. Just having the PCv doesn't do anything until it is mapped for the bike, default setting is zero equals do nothing. If you have the PCv then there is software to download so you can view and alter the mapping by USB from a laptop.

But note - it is possible to fit that resistor without the PCv kit.

I still get the occasional pop on the overrun but since getting it sealed no loud bangs and nowhere near as lurchy from off to back on throttle, it is a lot quieter at the engine end now.

I reckon the PCv works but it won't turn it into a fire breathing superbike, what it mainly does is smooth out the power and throttle response making it more fun to ride, plus adding maybe a couple of ergs. You should be able to change the exhaust without a PCv, or use the K&N air filter, but not both, it then needs the PCv to correct the mix from too lean. The PCv also allows you to play with the mix analogous to tweaking carb and timing (it does the timing too), there are two map slots.

[jefrs]

The bluing is a tempering colour, happens when you heat metals to nearly red hot and let them cool. The colour equates to a temperature, it is used to harden and temper steel, blue is very hot hard and brittle, straw is good for sharp blades. Just that chromium changes colour lower than steel does. When they're reheated they can assume a different colour. Mine has gone down from blue to pale-straw. Just don't expect shiny chrome to come back.

[2cvandy]

Thanks for the replies, I'll have a poke around later and see what's there, always a slight problem with a 2nd hand bike trying to discover what's already been modified. I'm not hoping for shiny chrome to re=appear, I just thought that if the blue is an indication that it's running lean, then maybe turning a different colour could indicate that problem had already been addressed, if that makes sense. If that were the case then the fact that it's stayed blue would indicate that it's still lean. Not overly concerned about any of this, just curious to know what I have exactly and to be sure it's running happily as I was planning on this one being a keeper.

[PeteF]

Not quite Jefrs
Bluing temperature for steel is around 280C. If you go to "just before red heat" you will get a grey tempering at around 430C.
Red heat doesn't start until about 540C and goes all the way to about 1000C (when it's bright yellow)
The tempering colour occurs as you heat the steel, not when it cools. That's how you know when to stop for the blue colour. If the steel is clean you can see it happening as you heat. Quenching in oil is the usual method for cooling from blue temperatures.
It also helps to keep the temperature even through the part so heating it in, say, a bed of brass shavings is the best way if you want an even colour.
Bluing is often used as a decorative and slightly rust resistant finish for parts on clocks. Gunmakers also use bluing but they tend to do it chemically (cold bluing)
I don't think taking steel to bluing temperature alters the hardness or temper.
Sorry, I'm rambling again

[2cvandy]

Okay, so I've just pulled the seat off for a closer look and my bike does not have a power commander fitted. Still running the original air filter though so I'm assuming it's ok running with just the resistor in place? As I said earlier, it certainly seems to run well enough, quicker than I expected to be fair. I loosened the silencer and the down pipe is tight in the head, although one of the clamp bolts did tweak up half a turn quite easily, so maybe that's the source of the occasional back fire. Having looked again closely at the down pipe it's blue near the head but fades to a straw colour further down the pipe, so all things considered I'm going to assume the mixture is close enough, "if it aint broke don't fix it". Having said that, I couldn't believe how rusty the seat pan was on a 5 year old bike, so the cover and foam have been removed for a clean up and painting session. I really should stop looking,,,,,,,,,,,,

[RayBeech]

Haha, jefrs bear me to it, and you have checked anyway. A PC is easy to spot as he says.