Triumphrat

drock003

Got one of my bikes to finally run pretty good, but how do you really know if a bike is running too lean?

EDC64

Kinda cruise steady, start opening the throttle (slowly) then shut it closed. Listen for popping sound while decel. If it's popping it's lean When the motor cools you can pull a spark plug. If the tip is white-lean. If it's black - rich. Idealy should be a tannish color.

nick_t

doesn't rich vs lean also affect the color of your pipes after you've been running the engine for a while?

i'm a newbie to this, so please forgive my ignorance if i'm wrong. i thought i read somewhere that if your carbs are at a good mixture, your pipes turn a nice blue color?

just seeking some info, yo!

nick

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"Each day is a journey, and the journey itself home."
-- Matsuo Basho

06 Bonneville T100 (AI removed, snorkel IN, stock otherwise)

RedBird

The best way I know of is to put the bike on a dyno with an Exhaust Gas Analyzer (EGA). I seriously doubt if one out of a thousand riders can "read" the plugs well enough to tell "rich" from "lean" from "spot on". IMHO, the hardest area to diagnose without an EGA is the mid-range, and that is where you do most of your riding! Many worry about changing their main jets and never ride above 6000 rpm enough to really matter. Of course on the dyno you can get a good reading over the whole rpm range. :-D

Larry

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Larry
2003 T-100 (790cc), NARK, NH Togas, 8100 rpm rev limiter, 158 main jets, 42 pilot jets (less than 1 turn out on pilot screws), stock needles--no shims. 13 A/F ratio from 1100 rpm to 4000 rpm; 12 A/F ratio from 4000 rpm to 6000 rpm; 13 A/F from 6000 rpm to 8100 rpm.:D
2007 Tiger 1050--White:D--SW-Motech crashbars, Skidmarx rear hugger/chain guard, Calsci +7 windscreen.

CAPTDON

Plugs tell all!!!

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CAPT D

Skyblue62

Check this site for how your plugs should look
http://www.theultralightplace.com/sparkplugs.htm

Also if your silencer outlet is sooty black then bike is too rich (should be medium to dark grey)

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Ian

ErwinM

i agree CAPTDON,
Plugs is the eaisest/quickest/cheapest

Tan - lean
Dark tan- light brown good
Anything darker getting too rich

Erwin

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Erwin

CAPTDON

Mine after 6000 mi were rite on- gap too!! May have to check them in another 3000 mi just for fun?

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CAPT D

mistermellow001

I agree that plugs and tail pipe color are good rule-of-thumb indicators of air/fuel mixture. Another good tool-less diagnostic technique is to momentarily hold your closed hand behind each pipe and feel for subtle differences in pressure and temperature between adjustments. This is a good one for quickie carburetor balancing if you don't have a manometer or some similar diagnostic tool.

Of course, seat-of-the-pants techiques are temporary measures. Nothing substitutes for a comprehensive tune-up after airbox, silencer, or other performance modifications. Dyno runs are okay if you really want to dial in the best performance, but the problem is that you have to do it multiple times if you're experimenting with different modifications and really need to see dyno results. I've never felt the need to dyno a bike but I wouldn't poo-poo it either.

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Guy

kdrake

neighbor not only checkes his plugs, he does it by riding at speed, clutching and coasting to a stop, then reading them. He claims that is a better gage without the changes from idling and going back home.