[swamp2]

My Haynes manual says that the stock spark plug cap has a 5K ohm internal resistance.  If the stock plug is a Bosch WQR8DC, this also has internal resistance, so it seems that Royal Enfield intends both resistances to be present.

I replaced the factory connector with a NGK LB05G plug cap that has 5K internal resistance, and I'm running an NGK BPR6ES resistor plug.  I've read that the resistance is needed to prevent EMF pulses from confusing the ECU.  I would imagine that either the resistor plug, or the resistor cap would be sufficient to accomplish this.

My factory plug cap had an external metal shield over it, per the attached image.  The NGK replacement is simply molded plastic and the metal shield didn't fit over it, so I left it off.

It's a bit redundant to have resistance in both the cap and the spark plug - any resistance in line is infinitely greater than zero ohms so you're correct - resistance in either will have the desired effect of adequately suppressing the EMI effects.  However if I was going to replace the plug cap, I'd put on the zero ohm one if I was sticking with resistor plugs.  The amount of current flowing through the wire/cap/plug is pretty minimal so consequently the difference in voltage drop seen by the plug will be small - but still, the more voltage getting to the plug, the better.

[litfire145]

Maybe I missed it but what should the plugs be gapped at?

[GlennF]

I use 0.027"  though I see 0.028" quoted a lot.

That said, a lot of people seem to just whack new plugs in straight out of the box without setting the gap at all without any major issues on these engines.

[axman88]

That said, a lot of people seem to just whack new plugs in straight out of the box without setting the gap at all without any major issues on these engines.

That makes sense considering that, at least with NGK, the standard plugs, the ones without a "wide gap code", the factory gap is .70 - .80 mm, which is .027-.031".

[robfred]

Thats what is great about this forum, lots of support from everyone.
For a RE newbie it is good to know that I can tap into others knowledge and follow interesting conversations
Thanks guys and girls 

[USBullet500]

Hi,

I am new to this forum. I bought a used RE Bullet 500 from a dealer.

On the day i brought home and unloaded from trailer, it ran fine but had low fuel light on. So i went and brought fuel in fuel can and filled it up full and ran on idle for a while. As the dealer used premium fuel with stabilizer, i let the engine run for a while and also with center stand on, i put it in 1st gear and let it run so that the gas gets into the system. After a while it just stalled.

I tried multiple times to do both kick start and switch start. But it did not help. As the fuel pump was turning on when i turn the key, I tried taking out the spark plug and it appears black(see picture). It was a NGKBPR5ES. But i had a spare NGKBPR6ES which i put on and it started fine. I was concerned about few things.

1) When i started in idle and put in full throttle, there were few drops of dark residue (like oil) that spilled out of the exhaust. Looks the same color thats on the spark plug. Is it a concern?

2) I was reading the previous posts and see people using Iridium spark plugs. Does the cap has to be changed when one uses Iridium spark plug? Does anyone have a link for both the Iridium spark plug and its cap.

3) I am having 2016 Bullet 500, and i see only one spark plug. I don't see a second spark plug on the other side. I see some youtube videos people replacing 2 spark plugs. Does anyone know if mine would have single or twin spark plug?

Thanks,

[gashousegorilla]

    Only the Indian domestic market had two spark plugs.   Not in the US  .  It sounds like you probably ran the battery down letting it idle for a while .. and the battery was probably weak to begin with if it was sitting for a long time.    And you may have flooded it reving  the motor.    I would charge the battery and make sure it holds a charge.  Put a new BPRES5 or BPRES6  plug in there .... A 5 will stay cleaner then a 6 .  The 5 is a  Hotter plug.  Autolite 64 is another good plug.    And then  take it out for a ride and blow it out. 


   And looking at your plug.... I would check check the condition of the spark  plug wire , the connections at the spark plug boot and at the ignition coil tucked up under the neck of the frame .    I've seen those stock metal spark plug boots fail as well.... poor and erratic spark .  While your at it , I would replace it with a NGK version.

[Arizoni]

1) When i started in idle and put in full throttle, there were few drops of dark residue (like oil) that spilled out of the exhaust. Looks the same color thats on the spark plug. Is it a concern?

Don't worry about it.  It's probably some of the rust preventative oil they put on and in things to protect the bike while it is in transit from India.

2) I was reading the previous posts and see people using Iridium spark plugs. Does the cap has to be changed when one uses Iridium spark plug? Does anyone have a link for both the Iridium spark plug and its cap.

The cap on most of the Royal Enfield singles is designed to slip onto the spark plug after the spark plug cap has been unscrewed.  Many of the fancy Iridium plugs don't have a screw on cap on their tip so, if you get one of these, you would have to change the slip on cap.
IMO, the iridium and other exotic spark plugs are designed for engines where removing the spark plug is damn near impossible (like my Toyota V6 has).  In other words, they will last almost forever (if they don't get fouled).  They in no way improve preformance or add horsepower and the spark plug is so easily changed on a RE single I can't think of one single reason anyone would want to spend 2 to 3 times the price of a basic spark plug for their bike.

3) I am having 2016 Bullet 500, and i see only one spark plug. I don't see a second spark plug on the other side. I see some youtube videos people replacing 2 spark plugs. Does anyone know if mine would have single or twin spark plug?

Gashousegorilla answered this question.

[tooseevee]

Hi,


1) When i started in idle and put in full throttle, there were few drops of dark residue (like oil) that spilled out of the exhaust. Looks the same color thats on the spark plug. Is it a concern?

2) I was reading the previous posts and see people using Iridium spark plugs.

3) I am having 2016 Bullet 500, and i see only one spark plug. I don't see a second spark plug on the other side. I see some youtube videos people replacing 2 spark plugs. Does anyone know if mine would have single or twin spark plug?

Thanks,

              (1) That's water (mixed with carbon from inside the header pipe and muffler). Water condenses out of the air because the inside of header pipe and muffler are cold and the exhaust is hot and when you revved it up it blew out of the end of the muffler. This water mixes with the carbon and blows out of the end of the muffler until the whole exhaust is hot hot hot. Then you don't see it any more. If you idle the bike too much in the garage without riding it and getting everything hot hot that water will lay in the muffler and rust.

              (2) Your engine doesn't need Iridium plugs. Regular plugs are fine.

              (3) You do not have a twin-sparkplug engine. Your engine has one spark plug. That's what it's supposed to have. There are twin-spark engines, but yours is not one of them. You could have a custom job done on your head and the other requirements for twin-spark, but there is no reason for you to do that.

               Also Google and read up on battery tenders. You should have one. The NOCO Wicked Smart Genius is a good one. My battery's being baby-sat by one right now down in my water heater room.

               Be sure when you watch Youtube videos that the work being done or explained is on the same model engine as yours. This takes homework about the models and memorizing what your engine (and the whole bike) looks like. 

                Good luck and do a lot of homework. Google is your friend.

               

[USBullet500]

Thanks everyone for your response. I really appreciate it.

I have the battery tender lead on it from previous owner. So i kept it to a stabilizer and checked with multimeter. Its at full charge. This issue happened due to the spark plug only. I will either stay with a 5 or 6.

[USBullet500]

Also the dealer changed oil and used 10W40 instead of factory recommended 15W50. Can that be a cause for spark plug issues i mentioned above?

[GSS]

10W40 should be just fine and you can switch to a higher grade at your next scheduled oil change. This should cause no issues with your plugs. Thanks.

[USBullet500]

Thanks.

[jez]

I've noticed the most ridiculous twaddle on forums re spark plugs, mostly emanating from India. They either are the correct heat range and  work or they are duff and don't either at all or for very long. Bosch have plugs made in Germany India and China, you can guess which work best.. In the UK there's been a spate of what appear to be chinese copy NGKs that don't work well and for long. I've had duff Champions straight out of the packet.  I run NOS Lodge that came out of a skip in my Enfield. If I have a good plug I keep it regardless what make.
On a primative engine such as the Enfield it makes didly squat difference as long as the plug is working and the correct heat range. Changing from a plug that is firing the engine reliably to a more expensive type will not make the bike go faster or sound different, but it might just pick up from low revs a bit better on  carburated   engines when you open the throttle hard. And some makes seem to be easier when kickstarting.  On my Fiat UNO I switched from NGK to 3point German Bosch and the car then ran cleanly from 45mph in 5th. On NGKs it didn't run well below 55. Since I had no 4th gear in my final three years of ownership that was significant...

[GlennF]

With regard to iridium plugs, my understanding is they perform the same they just last way longer in your typical multi-cylinder water cooled (car) application. In a car you are typically talking 50k between plug changes if the engine is in good condition.

50K between plug changes is not something you can reasonably expect on a single cylinder Enfield regardless of plug type.