Harley Davidson Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
530 Posts
Discussion Starter #1
I've read that with today's unleaded fuels with the ethanol, and now that bikes have efi, that you can't get a plug reading anymore. They all look pretty white because the fuel burns cleaner. True?
I've seen plugs from bikes that have Power Commanders, Serts, etc. on them and they look pretty white too. Reason I ask is because I had a PC on my last bike, and I see no difference in plug color compared to my current bike. I asked my "indy" about that, and he told me the same thing. Quote------> "Today's fuels make it very hard to tell how rich or lean your bike is by looking at the plugs. Not like it used to be with carbs and the older gasolines. Unless you're running really rich, they all look the same." <------ End Quote...... I've also seen that posted different places on the internet (so you know it has to be true! LOL).

I still have some plugs thrown in my toolbox from my old carbed EVO. Nice and tan color.

EFI has a lot of advantages, but sometimes I think carbs were better.
 

·
Retired citizen
Joined
·
23,369 Posts
IMO, if the plugs are whitish but not crusty white, maybe just a tinge of color, the engine is running near the correct AFR. 14.7 to the lean side and 13.2 toward the rich side. I like 13.5 AFR .
The carbed Shovels and EVOs had totally different ignition systems than the EFI engines too. Totally different animals !
Plug color tuning is old school for old school bikes.
 

·
Nocturnal Ancestor
Joined
·
6,673 Posts
Plug color tuning is old school for old school bikes.
When I used to own a drag bike(import inline four) I tried several different carbs and was always trying to get just the right mixture one day guy at track is using this thing called a GUNSON COLORTUNE lets you see the combustion in cyl and you adjust to your liking

I bought one and never used it...looking at it now, in the box think I paid about $100 bucks for it....its funny, had that thing for twenty years....just sitting on the shelf

Anyway :blahblah::blahblah:
 

·
Outlaw Nipple Poster
Joined
·
2,872 Posts
I read mine. They say "NGK". :)
 

·
Registered
Joined
·
219 Posts
Ronnie, you need to meet me at Goode Company and tell me how you pronounce "NGK". It shouldn't take more than 4-5 Lone Star's and a slice of pecan pie for me to get it right.


af
 

·
Retired citizen
Joined
·
23,369 Posts
I remember the Colortune units !
 

·
Outlaw Nipple Poster
Joined
·
2,872 Posts
Ronnie, you need to meet me at Goode Company and tell me how you pronounce "NGK". It shouldn't take more than 4-5 Lone Star's and a slice of pecan pie for me to get it right.


af
While we're there, we can go across the parking lot and play with guns at Carter's Country. As a side note, it's "Nippon Tokushu Tōgyō Kabushiki-geisha".
 

·
Keep on Ridin’
Joined
·
8,054 Posts

·
Registered
Joined
·
1 Posts
reading spark plugs

I know this is an old post ,but there are relevant comments that would be

unread and sometimes resurrecting an old thread is a good thing.

i was reading the tech article about re-jetting / tuning Kehin cv carbs.

Is there a reason for the..... line use new plugs when for the reading .

I always save a set of plugs (used) for this purpose as new plugs are really hard to read.

the way i have gotten the best 'read' is to get into the appropriate mode hold it

for at as long as possible pull in the clutch and flip off ignition.

stop on side and pull both plugs .(know in some maybe all states this is at least

technically illegal... in Ca you can be cited).

Am i thinking in the old man way and procedures have changed ?

Also when doing reads I have used pure unleaded (no alky) gas same octane as i always run.
 

·
I {Heart} Hookers.
Joined
·
31,321 Posts
^^^ You're correct..... If you start a bike with the choke on, you'll color the plugs. This gives a false reading.

This is also why plug reading for MOST PEOPLE is about as accurate as potato salad and a spoon, at a 100 yd rifle range. Face it.

If you want to know how accurately your bike is tuned, you run it on a dyno with a minimum, 2 gas analyzer.

If you pull your plugs after a good, long highway ride (min 30 min) and they're a nice light tan, you're at least in the ballpark, but that's only going to show your cruising range, which is slightly above idle, entering the midrange.

If it idles good with no spitting into the midrange off idle, your pilot is good.

If at midrange, you can goose it and it jumps, your slide needle is adjusted well, or is the correct one.

If you're in 4th gear, at 1600-1800 rpms, floor it. If the bike drops and scoots, you're good.

If it bogs, and letting off the throttle a little makes it pick up and go, your main is too large.

Outside of that......... weather, baro readings, altitude and fuel quality all affect what a carb does. Which in reality, is a partially controlled fuel leak.............
 

·
Outlaw Nipple Poster
Joined
·
2,872 Posts
Ronnie, you need to meet me at Goode Company and tell me how you pronounce "NGK". It shouldn't take more than 4-5 Lone Star's and a slice of pecan pie for me to get it right.


af
Nippon Toe koo shoo Toe gee yo Kaboo Sheekee Gah EE shuh.
 
1 - 12 of 12 Posts
Top