Running rich-all cylinders

[greyranch]

My 79 standard is running rich on all cylinders.Bike starts, runs and idles fine and really don't want to monkey with the carbs.Has unknown aftermarket turnout mufflers. Has anybody went with one step hotter plugs and with what results. I do run Premium 93 octane gas,maybe the slow burn in itself might cause a richer looking plug.I am currently using NGK BP6ES plugs and they are black on all cylinders.Any suggestions would be helpful.Thanks in advance,Brad

[petejw]

Hey Greyranch,
changing to a hotter plug wont fix ur
running rich mixtures, pretty much the only way
is to get into the carbs, before u pull them apart,


determine which circuit is causing them to run rich,

u have an idle circuit, mixture screws adjust this,
mid range circuit, slide needles can b adjusted,
mains circuit, main jets can b changed to suit.

also ur float levels can b adjusted as well,
all the above can affect mixture settings.

how does the bike perform overall,
and thru out the rev range?

check this link out on carb tuning,
myself and many others on here have used it with success.

http://www.factorypro.com/tech_tunin...m_engines.html


if ur bike is pretty much stock, u could possibly get away with
lowering ur fuel height by a mm or so.

[mro]

carb info needed

What kind of mileage you getting?
Have stock air box/filter? (filter clean?)

After market exhaust by it's self may or may not require re-jetting, so you need to know what your dealing with in the carbs.

Stock float height = 25.7mm
(carb on work bench upside down, from gasket mating surface to highest point of float)

Float height effects all RPM ranges.
When measured as above, lower height means more fuel in bowl, richer condition.(carbs are upside down)

Stock main jet 137.5, what does yours have?
Pilot screw settings (generally 1 1/4 to 1 3/4 turns out for stock)

Hardest part dealing with carbs is taking em off and putting them on, and it's not so much hard as it just takes a little time.


mro

[greyranch]

running rich

Hi All,thanks for the tips.As originally posted,I had some suspicions that possibly the premium fuel I get at the local Exxon might be giving me a rich fuel condition.I let the tank run about dry,fueled up with their regular gas and took the bike for a 20 mile ride.Pulled plugs when I got home and was surprised they are brown now.Maybe a coincidence.They were running black for the last three months on all cylinders and the bike ran so well I didnt want to pull off carbs yet. I will post later and tell you if my mileage improved at all.I have been getting around 30 with it Thanks again,Brad

[79XS11F]

Given that the bike is running put some sea-foam through it and stick to the regular gas. It the issue returns or persists you will have to get into the carbs to confirm the jetting.
Rob