spark plug

[Shakie NC]

been looking at the gunson colortune plug but don't remember the plug thread size any one know of hand. 10mm 12mm 14mm . I could pull the plug out and get it checked out but it going to be a few day's before I get to the bike. thanks for any advice.

[98valk]

u don't need it, been there done that.
just see ex.#2 and make sure the end of the thread area is not carboned up. should see metal spotted with carbon. much easier than the color tune.

https://fboignition.com/articles/sparkplugreading

[Joe333x]

been looking at the gunson colortune plug but don't remember the plug thread size any one know of hand. 10mm 12mm 14mm . I could pull the plug out and get it checked out but it going to be a few day's before I get to the bike. thanks for any advice.

According to NGK its 12mm.https://www.ngk.com/ngk-5129-dpr7ea-9-nickel-spark-plug
 I hope it is because I just ordered one myself. I found it cheapest here https://www.freedomracing.com/g4171-colortune-for-12mm-spark-plug.html

[hubcapsc]

The fellow who changed my timing belts also color tuned my bike...

https://hubcapsc.com/d.belts/color_tune_number_3.3gp

https://www.valkyrieflatsix.com/contact

-Mike

[TrapperAH1G]

I have no idea what this is!  Can someone explain or direct me somewhere?  I read the "reading the plug" and that seems simple enough, but don't have a clue what this tool is.

Thanks

[ckahler]

It's a spark plug with a clear window in the base. Lets you see the color of the flame in the combustion chamber. It may give some idle mixture information, but there is no way to see it while riding under different speeds and loads.

[Joe333x]

It's a spark plug with a clear window in the base. Lets you see the color of the flame in the combustion chamber. It may give some idle mixture information, but there is no way to see it while riding under different speeds and loads.

you can actually use it at any RPM to test. I read their whole instruction pdf before ordering it.

[WintrSol]

I have one that I got 20 years ago, to help tune my old CB450. I never got it to work well enough, probably because the ignition system is really weak on that bike. My ears and a good electronic tach worked better for me.
It says 12mm on the box, and I added a 14mm 'spark plug' to the kit. If you want one, I can mail this one, as I haven't used it since.

[98valk]

It's a spark plug with a clear window in the base. Lets you see the color of the flame in the combustion chamber. It may give some idle mixture information, but there is no way to see it while riding under different speeds and loads.

you can actually use it at any RPM to test.

well not really. an engine acts differently and has different requirements under load.
 and who is going to keep the engine rev'd at 4 to 6k rpms under zero load.

[Shakie NC]

thanks for all the advice, I have tuned it by exhaust heat at header, thought I try this. thanks again for all the advice.

[98valk]

thanks for all the advice, I have tuned it by exhaust heat at header, thought I try this. thanks again for all the advice.

something to considered.
too lean, header will be hotter, same goes if its too rich, it will be hotter. so not an accurate way to do tuning.
dropping the header and checking the color of the cylinder exhaust port, which should be light gray is considered a perfect mixture.