which spark plugs??

[Eddie]

High all, havnt been here for a while,, question is I have a 74 gt750, I put the newtronics electronic ignition on it a while ago (not sure if that matters),,,anyways I noticed that my left cylinder was smoking more than usual so I checked the plug and its very wet with I would say oil but not sure if its crank case or 2-cycle,,,, but I havnt changed the plugs in a while (around 2,k miles I think, give or take) and im going to change them ,, they have the NGK B6ES plugs, this is what is called for in a 74 model,,, so should I keep with these or go with a b7es which is colder? also I don't remember but I should not get the resistor plugs (r) since its electronic ign.? I don't remember? also just to clarify the left cyl. has always smoked more no matter what I do, and I have checked crankcase and oil level is fine, also check water level all the time and it might have lost a very small amount but nothing to get upset over, and I have checked and re-checked float level in carbs , but the left one just likes to smoke more, I stopped worrying about it a long time ago now,,, so which plugs???? B6ES are hotter than most gt's call for but I have had them in there for a while now...also I did change the spark plug caps and coils but I don't remember if the caps had the resistor in them or not? how can you tell? its been a long time since I changed all this (not checking points has me going longer between my tune ups, not used to it so some things like plugs are getting neglected , but that's ok....heheh) so b6es plugs have no resistor , not sure if I need one, also the resistor type plugs do seem to have more options like copper coated, iridium and so on...

[Craig380]

I would be tempted to go to the 7s (colder) and definitely fit platinums or Iridiums. These are pretty cheap online now, and never foul, need gapping etc.

Iridiums are ALL resistor plugs, so if you get those, definitely use non-resistor caps.

[yeadon_m]

On resistors, I managed accidentally to run resistance plug wires, resistor plug caps and resistor plugs. Runs absolutely perfectly from a 1st push start on choke through 100mph max speed to a nice 1000rpm idle. And elec ignition. It may matter, sometimes, but I am in the 'it doesn't seem to matter on a sorted, old bike, much' school.
Mike

[Coyote]

Look inside your plug caps. If you see a screwdriver slot, then there is a resistor. Some people take out the screw, dump out the resistor and replace it with solid copper rod..
This is not true in all cases as some caps have the resistor between the end of the wire and the elbow of the cap. If your caps have a long area between the wire entrance and the elbow. there is probably a resistor in there.
Personally, i don't like any resistance in my caps. I have used both and the spark is notably hotter with the non resistor cap I use.
I want to be corrected if I am wrong, but I believe the only reason resistors were ever used was to reduce radio interference. Old electronics used to be affected by this in both radio and TV. But that's all a thing of the past and has been for the last 20+ years. Why the resistors remain is a mystery to me.

[Eddie]

Thanks for the info, help, my plug caps are ngk but I just cant remember what I got and cant find the receipt for them, (old age is getting me) I didn't think it really mattered but I remember reading a whole article on it but cant seem to remember the damn out come ,,,I found some B6ES cheap so I got those but I am going to find a good set of b7es platinum and see what happens, I think I ran the 7's a long time ago and she seemed to smoke more and I don't think she ran that good if I remember, but I never tried platinum plugs...

[tz375]

I use iridium plugs and I still have stock coils and old resistor plugs with a Dyna S ignition and it makes big fat blue sparks and runs clean up to 8000 plus, so maybe it's not a big deal.

[Vintageman]

In theory you only need voltage to "bridge the gap". Once the gap is bridge is where things change with added resistance.

For one it changes rate energy dissipated from the coil. That may retard you timing a little. The energy of the spark is less when higher resistance is added. It still sparks but, may cause a small delay in fuel fully igniting. It may also cause the plug to not fire reliably if heavy contaminants about plug. It’s like trying to start a stick welder on dirty metal when the current is set low versus high.

A little resistance won't hurt most uses and with proper tuned engine. But since the old girls (with points) have no electronic devices that can be upset by a high energy fast rise of a non-resistive ignition system, I have run resistor less caps and resistor less plugs, and prefer to avoid both with resistor, but have OK

Iridium’s do foul and once they do they are hard to clean. I put spark plugs in my oven and turn it on self-clean and usually they work fine accept ones with resistors. Iridium's can help week energy ignition becuase the tip is fine and sharp and that makes it easier for spark to start. In some engines I have gained another 1000 rpm and in others nothing. It may also help your engine idle when energy is lowest low but usually something wrong with your coil,, battery etc if that is the case

I just revisted fine tip plug, that have no resistance (long threads only and not all heat ranges) B8EGV

[tz375]

Lots of good info. We used to race with B10EGV in our TZs but now I use Iridiums in BR9EIX or whatever the alphabet soup is and they work fine in most circumstances. But Vintageman is right that as long as you have enough voltage to jump teh gap and light teh fire, more doesn't help. But if things are marginal the extra resistance might be enough to cause a misfire.

[Eddie]

thanks guys,, when I put the newtronics kit in I replaced the coils as well, so I have new coils and electronic ignition, I looked at my plug caps and they have a number on the side ngk lzfh , I looked this up and it says they are resistor type plug caps,, so which is better a resistor type plug or not? I know it really doesn't matter but if im going to a colder plug I would like the best spark I can get which would be no resistor plug right? since the caps have the resistor,, ? again I know it probably wont matter ,,thanks for all the info you guys are great!!

[Coyote]

You sure you got that right? LZFH is what I run. They are non resistor. You might want to compare dimensions

[Coyote]

It's all very confusing. Apparently the LZFH comes in several configurations. If yours are short like the one pictured above, it is a non resistor plug cap. If it is much longer then it is the resistor type.
Also that number 8710 I don't think is available anymore or has been changed. The plug caps I have are LZFH 8381. They are identical to the 8710 above

[ConnerVT]

No number means no resistor. The number in the part is the resistance in K ohms.

Example: LB05E is a 5K resistor cap.

External appearance
L: 90° Elbow type
S: Straight
X: 102° Elbow Type
V: 120° Elbow type (long)
Y: 120° Elbow type (short)

Adaptable plug thread size
B: 14mm ø thread
D: 10 & 12mm ø thread
Z: 10, 12 & 14mm ø thread

Resistance
01: 1 KΩ
05: 5 KΩ
10: 10 KΩ

Adaptable plug terminal
E: For terminal nut or integrated terminal
F: For terminal stud

Accessory
H: Compact type
P: With Special Water-Proof Cover
K: With Silicone Water-Proof Cover
M:Rubber Sheathed
F: For 5 mm ø high tension cord
Y: With handle
Z: Special shape

[Coyote]

It's the wording that gets me sometimes. I have the box right here. It says: "LZFH. stock # 8381. Spark plug cover". It's a cap but it's called a cover So you have spark plug covers, spark plug caps and resistor covers. No discernible difference. They all look alike. As far as I can tell, spark plug covers and spark plug caps are one in the same.

[Eddie]

Wow, I had ordered my caps and I believe my coils from Hvc cycle a long time ago , I looked up the plug caps and it says resistor , but like was said they have different caps with I guess same model number, some are resistors and some are not . I tried posting a picture of my plug caps but I wasn't able to , the number on my caps is 33u not sure what that is .

[Eddie]

Lzfh is by itself on the cap, and then at the bottom of the cap where the rubber boot fits it's the number 33u, So the number is not with the letters lzfh so I guess mine are not resistors , wow sport for something so simple turning into something so difficult , but this has started to become I interesting ..