Spark Plugs
- Thread starter chasesa
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chasesa said:
http://www.sparkplugs.co.uk/pages/prici ... le-ccp.asp
BP7ES
BP7EVX
BPR7EIX (R = resistor plug)
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L.A.B. said:
BPR7ES too of course...
I quite like the BPR7EIX. Much more tolerant of rich carb settings. Purists will say that is using them to mask problems of course, but after many many hours fiddling with Amals that went from too rich to too lean with seemingly no in between BPR7EIX did the trick.
Cheers,
- HJ
ashman
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Some say Champions are crap, but I have run them in my Norton all its life and have never had any problems with them, but 3 times now I have put NGKs in it when I couldn't get Champions and every time with in a week of using them they have started to miss fire at low revs, I don't get this problem with the Champions, I have always got long life out of my plugs, but everone to their own so I will always stick to Champions.
Ashley
Ashley
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Luck of the draw then, Champions are the ones I've had out of the box C'do failures in V8 packs of them. Never had issue with NKG or Bosch platinums 4 electrode plug.
I've had Champions prior that lasted years in mowers and boats. Not single brand shows up as worse than another - listening to report last 12 yr. i highly recommend don't change anything else at all on bike on each new plug change or can waste a weekend thinking it can't be a brand new plug, until you finally dig old ones out of trash and prove it was.
I've had Champions prior that lasted years in mowers and boats. Not single brand shows up as worse than another - listening to report last 12 yr. i highly recommend don't change anything else at all on bike on each new plug change or can waste a weekend thinking it can't be a brand new plug, until you finally dig old ones out of trash and prove it was.
There is the NGK BPR7HIX in addition to the BPR7EIX. The HIX is the same as the EIX but it has a platinum pad welded to the underside of the ground electrode. It may help with longevity if you're using a wasted spark coil setup that has reversed polarity on one of the plugs. Probably not a big deal, but as long as you're spending the money for an iridium plug, you might as well.
One thing I did find out about mixture tolerant plugs though. I have a single VM34. I was chasing the jetting in the pilot circuit for quite a long time. I replaced the float valve, set the float height, and still had to go down to a 27.5 pilot jet to get the air screw in the 2 turns out range. The rear vent tube never dripped gas but it did show a wet ring on my finger whenever I touched it, so I lowered the float around 1-2mm. I went back to a 30 pilot jet, 1.5 turns out, and the bike just came alive all through the throttle range, but especially at the lower range where the pilot and the slide have the most effect. I was surprised as hell because I always thought the bike ran ok. I didn't have fouled plugs. There was an article about reading plugs mentioned awhile ago. They said that reading the porcelain can't tell you much about mixture unless you're way off. The base ring of the plug is a better indicator for jetting. Here's a different site, but the same idea.
http://www.angelfire.com/fl4/pontiacdud ... plugs.html
One thing I did find out about mixture tolerant plugs though. I have a single VM34. I was chasing the jetting in the pilot circuit for quite a long time. I replaced the float valve, set the float height, and still had to go down to a 27.5 pilot jet to get the air screw in the 2 turns out range. The rear vent tube never dripped gas but it did show a wet ring on my finger whenever I touched it, so I lowered the float around 1-2mm. I went back to a 30 pilot jet, 1.5 turns out, and the bike just came alive all through the throttle range, but especially at the lower range where the pilot and the slide have the most effect. I was surprised as hell because I always thought the bike ran ok. I didn't have fouled plugs. There was an article about reading plugs mentioned awhile ago. They said that reading the porcelain can't tell you much about mixture unless you're way off. The base ring of the plug is a better indicator for jetting. Here's a different site, but the same idea.
http://www.angelfire.com/fl4/pontiacdud ... plugs.html
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That is a very good article on plug reading on unleaded fuels.
You will want to be careful with trying to get the base ring completely gray on a Norton motor. You will probably see pepper flakes on the insulator before it is light gray all the way around. Pepper flakes will tell you you are too lean or the plug is too hot or you have too much spark lead.
If the engine is so rich it is darkening the insulator then it is also causing undue wear on the rings and cylinder walls.
The higher the compression ratio of the motor the colder the heat range of the plug needed. NGK grade 7 is for slow speed or low compression motors, grade 8 is best for 9 or 10 to 1 motors being used in a sporting manner, grade 9 or colder is needed for high compression hot rods or race motors if you are jetting for maximum power. Jim
You will want to be careful with trying to get the base ring completely gray on a Norton motor. You will probably see pepper flakes on the insulator before it is light gray all the way around. Pepper flakes will tell you you are too lean or the plug is too hot or you have too much spark lead.
If the engine is so rich it is darkening the insulator then it is also causing undue wear on the rings and cylinder walls.
The higher the compression ratio of the motor the colder the heat range of the plug needed. NGK grade 7 is for slow speed or low compression motors, grade 8 is best for 9 or 10 to 1 motors being used in a sporting manner, grade 9 or colder is needed for high compression hot rods or race motors if you are jetting for maximum power. Jim
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