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[jefrs]

Sooty Plugs, "they all do that sir".



My NGK BPR6EIX (Iridium version of the BPR6ES) fouled up (EFI-500 C5) after replacing the Bosch-India WR7DDC4 (twin electrode). Apparently this is a common failing of the Iridium plugs. I replaced it with a new WR7DDC4 which fared no better. Meanwhile I've been running a lot of Redex through the tank and have cleared most of the soot away. A lot being nearly enough for a car's tank but it's not been smoking and seems to have done its job, flushing it away with another petrol refill now. Even so the WR7DDC4 was still getting blackened. The motor is supposed to run lean so that is wrong. I do have free-flow 50s exhaust system, K&N and Power Commander (PCv) so probably not running on normal mix. I can dual map on the PCv so may try the weaker base mapping to see what happens.



I believe sooting is a (partly) symptom of plug fouling i.e missing the odd spark and leaving fuel behind to enrich the next bang, so once it starts fouling it only gets worse. You can cure the symptom by cleaning the plug but not the cause, 'wrong plug'. Hence my search for the 'right plug' ...



So next I fit the CGT plug (EFI-535), the Bosch-India WQR8DC and this fares much better. The "Q" is 'quick heat', the "R" is 'resistor' (suppressor). It's a version of the Bosch WR8DC. It's a slightly hotter plug but both WR7DC and WR8DC are equivalent to BPR6ES, i.e. it's not a lot hotter, and it is indian and looks it (wonky offset electrode anyone?)



It can be tricky to find a good equivalence table. Linky - http://e28-535i.com/upload/Bosch_NGK_cross_ref.pdf



Most of the soot is now gone but I'm thinking it might like an even hotter plug. That would be H's BPR5EIX but I don't like Iridium now. BPR5ES is equivalent to a WR9DC. NGK numbers go down and Bosch numbers go up as they get hotter.

[Rattlebattle]

Like you, I installed the same iridium plug to replace the original Indian Bosch. I have since replaced it with the cooking NGK BP6ES. Engine now starts first kick. Empirically, I don't think iridium plugs suit the UCE; others have had the same problem.

[nigelphoto]

There are at least half a dozen other Threads on here about sooty plugs such as 'EFI Idle' and 'Spark Plugs always fouling' and the answer is always the same. The EFI engine runs lean (look at the insulator core and central electrode only) and it always pops and bangs a bit on the overrun. The soot is from all the the crap they put in petrol nowadays and a plug chop just can't be compared to good old 100 Octane from days back when tha wer a lad. Fuel injection on a big single is notoriously difficult to control properly and a bike that sells for the equivalent of £1850 in its home market isn't going to be a Brough Superior! I've stopped worrying about whether North Korea has nuclear weapons, if Donald Trump is to be the next US president, what's for tea and sooty plugs - i get on it, start up and pin the twist grip.

[jefrs]

I started a new thread in my quest to find the right plug and gap to cure sooting. What I've done so far seems to be working

The WQR8DC just came out with the electrode colour looking perfect but I'd had it set to (cof) 'recommended for Bullet' 0.020-in which appears to be wrong for this EFI-500 motor, it wasn't pulling up the revs nicely this morning and yesterday evening. Only the tiniest bit of sooting now but still burning off the extra dose of Redex which is an oil and will blacken it..



I think this motor likes 0.7-0.8mm spark gap, Try again. But the electrode on this plug overhangs the centre, it's not a good plug. I could put a BPR5ES in there but I think I'll go and get a BPR6ES for it instead. I do notice the ceramic on the WQR8DC electrode is much thinner than the BPR5ES. The only german Bosch W-7/8/9 available locally are lawnmower types the wrong size (or quad electrode) but I can get the french NGK BPR-6/5 ones easy enough.



Going for standard 0.70mm spark gap

[jefrs]

Nigel - it in my nature that, "if it ain't bust, fix it" but also I must know, "the ins and out of a donkey's earhole" or, "brain like a fart in a colander, every hole at once".

My PCv etc was added from near-new to cure the injector's foibles, it could have been mapped better to start with but was probably mapped to run on any old rubbish from sea level to over 18,000-feet. I feed it 98-99 RON. The PCv etc etc works by the way, pinning the throttle will have the front wheel up by your ear. I've cured the banging on the overrun for the most part, I can induce a musical one by snapping the throttle shut for amusement, it moves cars out of the way in traffic



Righty ho! Lunch break over, back on me bike it's a nice day

[ric]

A brilliant day for a ride I've just returned from a 200mile+ round trip and as a one off decided to use dual carriageway/motorway option.
What did surprise me despite traveling much faster than I normally do is that the fuel consumption hardly changed. I guess having a strong tailwind outbound and the wind speed dropping for most of the return was a big help.

[nigelphoto]

Well ric, glad you had a nice ride today but have you had a look at your plugs? Are they sooty? Thats the question . . . Answers on a postcard, preferably with a Weston-super-Mud view on it.

[papasmurf]

nigelphoto, I was in Weston Super Mud last Thursday evening, enjoying a pint and a curry at Scallys.

[jefrs]

It was nice out. Only went to ye shoppe then for a blat around some country lanes. Got pelted by some tiny beetles on a couple of occasions, tasty. Got home just before the rain.



Not pulling up through the revs was not wanting to go much over 3500rpm. With the WQR8DC opened to 0.70mm I now got nigh-on 6000rpm in 3rd under load, gradual build up, slight incline up. I was expecting the rev-limiter to cut in at 5500rpm. The rev-limiter did cut in at 5500rpm in 4th. I'd need more road to find how high it will go in 5th.

I do not normally ever take a motor to the red-line but it was running sweet as a nut and on fresh oil: experiment. Going 'past' the rev-limiter (Smiths tacho) in 3rd did not sound ragged, that was a bit weird.



My gearing spreadsheet for the C5 (110/80-18 38/18T and ratios given in the handbook) calculates thus -

5mph/1000rpm in 1st,

8mph/1000rpm in 2nd,

10mph/1000rpm in 3rd,

13mph/1000rpm in 4th and

16mph/1000rpm in 5th.

Doesn't sound like much of a spread but at 4000rpm (cruise) is 21mph in 1st, 31mph in 2nd, 41mph in 3rd, 52mph in 4th, 63mph in 5th.

At the red-line rev-limiter 5500rpm 3rd is 57mph 4th is 71mph and 5th 86mph (but not likely) and 6000rpm in 3rd 62mph and yes it was heading for that. Last look at the plug the WQR8DC was clean (hard carbon blackening not soft soot) and the right colour on the ceramic/electrodes. Weather permitting I'll repeat with the 'better' NGK BPR6ES or BPR5ES

[Beezabryan]

The more crap I read about "modern" Enfields the more I am determined never to have one, life is too short.
Why have a bike where a PHD in orgami is required to keep it running or even get it started
Our bikes are for riding not buggering about with and composing erudite scripts explaining why an Enfiled of whatever guise is a POS