Could someone post a photo of a spark plug with color for ideal mixture strength

DennisMo · 2026-06-15T17:20:45-0600

With my 850 engine rebuilt I am now looking at the Mikuni. Clearly the choke is leaking as the right plug is soother than the left plug so I have ordered
a new choke plunger. I owl be grateful if I could see some photos of spark plugs where mixture strength is close to ideal.

Mine are sooty.
With thanks
Dennis

gortnipper · 2026-06-15T18:04:12-0600

Could someone post a photo of a spark plug with color for ideal mixture strength

gortnipper · 2026-06-15T21:53:17-0600

oops - cant see that and I posted between meetings and now cant edit it.

https://honda-tech.com/forums/attachments/engine-management-tuning-124/473597-spark-plug-reading-pictures-densosparkplugchart.jpg

jseng1 · 2026-06-16T09:22:03-0600

more info on this page:
https://jsmotorsport.com/fcr-carbs/

Carl H · 2026-06-16T11:18:24-0600

Is that with high mileage plugs using leaded fuel?

htown16 · 2026-06-16T11:48:10-0600

kommando · 2026-06-16T12:38:02-0600

Modern fuels mess this up, fine if you can get old fuel.

DennisMo · 2026-06-16T13:29:44-0600

Many thanks.
With my Mikuni I am running to rich at low rpm and have sooty plugs.
If I lean out the low speed circuit to get rid of the sootiness, I get lots of exhaust pops on
overrun and when bike first started from cold.
The idle air screw is about 1 1/4 turns out from its seat to stop the popping.
So I thin this tells me it is time to go for a larger size idle jet
I am going to change the idle jet to next size up before reporting back
Thanks again
Dennis