Reading Plugs

I have a question about reading plugs for setting up carbs. Does non-leaded gas with ethanol still give the black-brown-tan-white continuum, going rich to lean? I'm getting black or white on the electrodes with not much else in between.

Thanks,

I know that additives do change things, but yes you still should have a light tan to brown when all is right. I've seen red tints on car plugs but never on my Norton. Dunno why.

I personally don't think you can tune by plugs any more. Too much junk in the fuel. I have a pretty stout DRZ470. It got jetted on the dyno. I've loked at a lot of plugs in my life. Most people don't know that you need to do plug chops under load. They just look at them and say, its rich or it's lean...Not so accurate.
But in the last 25 years or so, they've put so much stuff in the gas that it's impossible to tell by looking at a plug.

A plug chop is still a decent (quick, free and easy) indicator of extreme conditions - Black = rich, White = lean.

However, the color variations are more grey even when within fairly good jetting range, and definitely wierd when regional fuels with "nitrogen" "techron" and who knows what else added.

So, being that you are already getting Black or White, you need to get into the gas analyzer (sniffer) testing to go any further.

What kind of step is taking you directly from Black to White? Usually, you can only go to opposite ends of the color range with VERY significant mixture changes.

grandpaul said:

A plug chop is still a decent (quick, free and easy) indicator of extreme conditions - Black = rich, White = lean.

However, the color variations are more grey even when within fairly good jetting range, and definitely wierd when regional fuels with "nitrogen" "techron" and who knows what else added.

So, being that you are already getting Black or White, you need to get into the gas analyzer (sniffer) testing to go any further.

What kind of step is taking you directly from Black to White? Usually, you can only go to opposite ends of the color range with VERY significant mixture changes.

Click to expand...

Here's some history. I put the single 34mm VM on my 850 that I had been using ten years ago. I cleaned it it out with carb cleaner and air and left the settings as they were. 35 pilot, 3.0 slide, 1.0 air jet, 159 P-4 needle jet, 6DH3 needle, and a 260 main. It ran fine back then and got around 50mpg.

I've been running it since getting the bike back together last summer. The idle mixture was now way rich by the fact that it ran cold with no choke and I didn't get a response to opening the air screw till about 3 turns. So I went to a 30 pilot jet, nearly the same. Went to a 25 pilot. Now it runs great after a few minutes with the screw out 2 turns without the choke. No hesitation. But the plug is still black. I have a perfect road with a hill for plug chops. At cruise in fourth, about 1/8 throttle, plugs white. So, I went to a 2.5 slide. It now pulls much stronger from idle to around 1/4 throttle. Plug's still white. 1/2 throttle plugs white. WFO, the plug''s are black, gotta ditch the 260 main. Weather permitting, tomorrow I'll pick up a 250 and a 240 to see. I don't spend much time at WFO throttle.

When I say the plugs are black, I mean covered with soot. And by white I mean the ceramic is entirely white. They come clean after only a few minutes of running at anything but idle. The plugs are Bosch Platinum WR7DP's which are a wire electrode platinum plug and seem to be Very tolerant of rich jetting. Maybe the WR7DP's are too hot making them impossible to read, but they are supposed to be a swap for a 7 series NGK, I think :?:
http://www.sparkplugs.co.uk/pages/prici ... ef-ccp.asp

Edit:

I just ran the coversion again and came up with the 5 series plug as equivalent to the NGK 7's. I'm using too hot a plug

The Bosch Platinum WR7DP's are good ,I have bought and run 6's next step cooler and they are too cool.
Your finding the settings rich is not a surprise as many of the volatile elements have been taken from the gas.
It will take 50-60 miles or more to get color on the plug and than only a ring at the base of the ceramic you will need a glass with a light to see. Gone are the days of reading plugs with the naked eye. White plugs with the naked eye is what you want. Don't forget that 50=60 MPG (US) is also a good tool for tuning a Norton or a Triumph but BSA's get a bit less. A very dull flat Black with no thick build up at the top of the piston after a hard ride would be good as an indicator over all.