Wrong grade of plugs?

[turbopete]

Hey guys.

I have the BP6ES plugs in my XJ1100 that the manual says are stock. It had BP7ES in it when I bought it. Is the 7 the more common plug to use? This is why I ask:

Although the bike rides ok, the carburation is a bit off. The settings for float level I read on here are nowhere near what I need to use to get it to run, so I set it up like the manual says with a clear tube. Now the float height measured with up-turned carb is about 2mm lower than you guys suggest, yet the plugs indicate a lean condition. I pulled the carbs, and set all the floats different, each 1mm up from the previous starting at 19mm from the carb body mating surface to the lower step on the base of the floats. This should have a) given me a super-rich reading and b)given me a different plug reading for each plug. I went out for a ride, warmed her up and did a 1/2-mile full-throttle run up a steep hill then chopped the engine. All four plugs are showing pure white, as in lean condition. I'm wondering if I am using too hot a plug for the test?

Any suggestions?

[TopCatGr58]

Hey TurboPete,

Just so happens that NGK has our plug as an example for heat ranges, and the 7 is COLDER than the 6!!


Have you seen the mega thread that Mike Hart posted about his trials and tribulations with trying to adjust and rejet his XJ after putting on Indy Filters? He went up many sizes before he started to see a color change. Do a search for Plumbing, and you'll see a thread with over 100 replies, check it out!

Someone also posted a while back that due to the more efficient types of engines, electronic ignition, and cleaner fuels, that it's not uncommon to see white plugs and NOT be running LEAN!

Food for thought!?
T.C.

[Geezer]

With most modern fuels (in the USA anyway) reading plugs like we did in the old days is a thing of the past. The stuff they're putting in gas now doesn't leave the ring down inside.

If you ride in town a lot 6's are OK. Most of the older bikes came with plugs that were a bit on the cool side anyway.

Geezer

[turbopete]

Stuff it I'm going to level up the floats and take it to the dyno for an A/F reading. No more guessing then...