2500-4000 RPM Lag

[sidecarKev]

I put my new floats in and the bike runs much better. One thing that is bothering me is the RPM range from 2500-4000. It kinda lags. According to carb info I've seen it is a function of the floats. I set them a little leaner in hopes of a change, nothing. How can I tell if the engine is running rich or lean in a certain RPM range?

[TopCatGr58]

Hey there Kev,

This lag, what gear are you in? In first it shouldn't be too noticeable, but again, you've got a much heavier load than a stock XS. And theses bikes power band is notoriously above the 3500 threshold, especially in the higher gears! Yes, these engines do have good torque, but you probably need to keep the revs a bit higher, not so far down in the "lugging" range.

From what I've read, people gauge the richness/leanness by how it responds, but they've stated that the plug colors are more for the mains when you do a throttle chop! If you're plugs are fairly white=lean; black-carbon-sooted=excessively rich, should be light tan brown color! For idle, some folks use the Color Tune system!? Idle settings do affect the lower rpm range up to the mid when the mains kick in!

A bog off idle could be too rich, improper timing, poor vacuum advance, and I'm sure many others that the Carb Gurus can chime in with. I rarely run mine below 3K rpm, I've got a slight decrease in low end grunt due to 4-1 pipes, and I like to use the engine for braking as well, and the throttle response is much quicker from that point on up!! Just some thoughts!
T.C.

[sidecarKev]

Well I let the bike run in this rpm range for quite a while tonite. Pulled the plugs and they were black. Also noticed #3 was in and out, causing a knock at higher RPM's. Took the carbs out and reset the float a little leaner. Put them back in and like magic I had tons of power at low rpm's. Finally. Now I can roast the tire on left hand turns.