[JVS]

Hi everyone,

Hope you're all doing well and are enjoying your weekend. Just wanted to ask what you guys/girls think of the condition of the exhaust valve, as shown in attached pictures.

I installed the Hitchcocks header pipe today, so had the chance to take a few snaps. I haven't ridden the bike much in the last six months due to crappy reasons. Basically it's done approx 13.5k miles. Is it running too lean? With the new header pipe on, and new a silencer (with glasswool) I installed a couple weeks ago, I haven't had any backfires in the short distance I rode today to test it out.

Your assistance will be greatly appreciated.

[caricabasso]

It seems that the motor  burning a very lean air-fuel mixture, so a very high operating temperature.
This appears from the light brown color of combustion residues.

[SteveThackery]

I think it looks pretty normal, to be honest.  If you've got a UCE then it's pretty hard for the mixture to be wrong anyway, because it runs closed loop (stoichiometric) most of the time, and rich the rest of the time.

I think it's OK, but it will be good to hear other views.

[JVS]

Thanks caricabasso and Steve. I'm aware that these engines are meant to be more of a 'lean-burn' type. Those pictures were taken directly after removing the stock header pipe for the first time. I've checked the spark plug many times, and it has always shown a nice mixture: brownish/tan tinge in the middle. I also just went for a longer ride and gave it some Enfield twists of the throttle, and surprisingly I got no backfires.

With the EFI silencer on, I used to get backfires occasionally on deceleration and I used to like them haha. But anyways, I'm happy with the header pipe. The thump has become more deeper and I did notice an increase in acceleration throughout the gears. Only downside is that my stock header pipe never blued, besides the oxygen sensor area at the back. It had a brownish/gold tinge that I liked.

With the Hitchcocks header pipe, it got dark blue at the bend straight away (within 1.30mins) after the first start with 0km/mi on it. I guess that's because the stock pipe is double walled, whereas this one is single walled, and quite a bit lighter than the stock one.

[SteveThackery]

I'm aware that these engines are meant to be more of a 'lean-burn' type.

Yes, that was primarily when they introduced the AVL engine (commonly called the lean burn) to meet the emission requirements back then.  If I recall correctly my Electra X (which had the AVL engine) had a two-way cat and an air injector in the exhaust port. 

Since then we've adopted three-way cats, which require a stoichiometric (i.e. neither weak nor rich) mixture for most of the time.  Even so, it's probably still weaker than the old iron barrel used to run.

I'm still hoping some others will comment on your photos.

[GSS]

Looks pretty good at 13.5k!

[High On Octane]

How many actual miles are on the bike?  I see you mentioned 13.5 miles, but I assume that is on the new exhaust.  To me, the valve doesn't look necessarily lean, but it looks like it is seeing some serious heat.  In my opinion, the stem on the exhaust valve should have a bit of black carbon built up on it as opposed to being so clean.  Perhaps you just have really awesome fuel that doesn't leave any deposits behind.  IDK

But, what really concerns me is that "ring" on the stem about 1/2" above the valve seat.  With the recent knowledge of exhaust valves failing and grenading a couple of motors, I would be suspicious of that "ring", as it appears to be in the same spot that no bs' valve failed.  Not trying to scare you, but you did ask for opinions.  FWIW I believe Ace mentioned having a quality stock replacement exhaust valves now.  Perhaps he will chime in here.

[ace.cafe]

That orange colored band on the valve stem is where they break off.
The ring on the stem is where the 2 pieces of the valve are joined, typically by friction welding.
That is where the stem and the head sometimes part company.

I suspect that removing the catalytic muffler will go a long way toward reducing the heat held inside the exhaust system, and possibly helping the longevity of the exhaust valve. I believe an appropriate mixture adjustment to compensate for the free flow kit would also help. A Power Commander would allow that.

[JVS]

Thanks for all the input folks! I really love this forum 

How many actual miles are on the bike?  I see you mentioned 13.5 miles, but I assume that is on the new exhaust.

Scottie, 13500 miles on the bike with the stock header pipe. I've only put about 20 miles on the new header. Also, I've been using 95 octane fuel since I bought the bike. I posted the pics mainly because of that ring thinggy. I was kind of surprised to see it too. Even though I was scared a bit before, I'm not feeling that bad anymore 

ace, the new header pipe seems like a straight through pipe with a larger OD, and is single walled. The dia only decreases when it reaches the end of the header pipe. See attached pic. I think the mixture for now is okay, but I will check the plug again tomorrow anyway. I had also increased the TPS voltage a bit a few months ago, to keep it a tad on the richer side throughout the range.

The bike likes to keep going strong, and I hope it will remain that way for times to come 

[SteveThackery]

I had also increased the TPS voltage a bit a few months ago, to keep it a tad on the richer side throughout the range.

Mate, you know what I'm going to say, don't you?!!

Increasing the TPS emphatically does NOT make it richer throughout the range.

It only makes it richer when it's running open loop.

It runs open loop under these conditions:

1/ For 2-3 minutes after a cold start

2/ For 90 seconds after a hot start

3/ At high engine speeds and large throttle openings (i.e. when running "balls out")

At all other times it is running closed loop, during which the mixture is controlled solely by the O2 sensor.  This is - effectively - a requirement of our emission legislations.  The catalytic converter only works properly when the mixture is stoichiometric, and the engine must run closed loop to achieve this stoichiometric mixture.

If anyone tells you've they've seen a difference on an exhaust gas analyser after tweaking the TPS, it's because they did it wrong and didn't leave the engine for 90 seconds after EACH hot start before measuring the exhaust gas.

[JVS]

I was waiting for that, Steve  I remember you had mentioned something about that in your original TPS experiment topic, I think. But thanks for reiterating, I will forever remember it now 

I was trying to reassure myself that I am doing it right (wrong). But hey, the bike is running fine for now. I think I need to stop installing stuff every few months, and just ride more!

[ace.cafe]

From what I have read, I think that Hichcock header pipe has a removable reducer at the top which matches the port exit diameter to the I.D. of the reducer. I don't know how far into the pipe this reducer goes, but presumably it goes out to somewhere near the first bend.
If it does have this reducer in the beginning of the header pipe, it would be good to use it. It will improve extraction, and thereby improve torque. Removing it and running full open diameter header will make a mismatch of duct diameter too early in the system, and while it may have effect in anti-reversion, it has negative effect on exhaust speed for extraction.
So, if you have the reducer, which I presume that H still includes with that header, I recommend using it.

[JVS]

Hi ace,

Thanks for that. I couldn't notice any obvious reducer at the top. But if you say so it must be there. And based on your explanation, if it wasn't there, I would've noticed a decrease in performance I guess. I was just in a hurry to install it and see how it will perform. But see attached pic. That's how it looked after riding it only about 4 miles. Compared to the stock header, which has always been brownish at the bend as seen in my previous post.

I think it's a good bet that the blued area is the one where the reducer extends to 

[ace.cafe]

Hi ace,

Thanks for that. I couldn't notice any obvious reducer at the top. But if you say so it must be there. And based on your explanation, if it wasn't there, I would've noticed a decrease in performance I guess. I was just in a hurry to install it and see how it will perform. But see attached pic. That's how it looked after riding it only about 4 miles. Compared to the stock header, which has always been brownish at the bend as seen in my previous post.

I think it's a good bet that the blued area is the one where the reducer extends to 

I haven't seen it. I just read from users that it was there. It may or may not be the same as the earlier header from H.
Anyway. If there is some length inside the header that continues the same port exit diameter for some length, that would be a good thing for tq.

[SteveThackery]

I think I need to stop installing stuff every few months, and just ride more!

No, no!!  This is a Royal Enfield we're talking about.  Your contribution to the greater good is to keep installing stuff until it doesn't work any more.  Every RE owner knows this.