A/F question

[tothemax93]

I have Marks 4-1 with the needles shimmed .30. Its running good. I've been racing and the times are what I think are respectable. I decided to look at the plugs after I raced last week. it looks like its running pretty lean. My question is, what do I need to do to richen it up a little. I know that the A/F screws are designed for low RPM's. Would I start with those, or is this a needle adjustment. It runs the same all the way up though the RPM's. Which way would you turn the screws to richen it. Any other advice would be appreciated. My next real step would be a morleys kit, but a little low on funds for now. I have to work with what i've got.

 

[44boyd]

You'd turn them out to richen them up. If you go over 4 turns out, probably time to change the main jet.

 

[sdt354]

Turning them out richens the mixture. I'm around 3 turns out with a 4-2 Mark's pipe. .022 shim on the stock needles. And my Y is trimmed and shimmed about 1/2 inch. The idle mixture circuit extends into the midrange somewhat. I'd cheeck float levels first, wet check. The plugs are not easy to read. I've always had ghoast white electrodes no matter what. A clean shut down then a read of the whole plug. A morley's kit is a good way to go. I hope this helps.
Steve-o

 

[[email protected]]

If its running good, I wouldn't worry about the plugs being a bit white.

 

[tugla]

as steve-o said a good wide open cut read and yes double check the floats and then maybe a main jet change.....but again if it aint broke dont fix it hahahah but what fun is a max if you dont play with it right....

 

[tothemax93]

as steve-o said a good wide open cut read and yes double check the floats and then maybe a main jet change.....but again if it aint broke dont fix it hahahah but what fun is a max if you dont play with it right....

I have the, if it aint broken mentality to. I've read a lot of post from guys that started playing with the carbs and ended up with a nightmare. I just don't want to hurt anything by running to lean, and of coarse If I can run a little fast with proper a/f then thats a bonus.

 

[one2dmax]

You can't really lean these up enough to hurt anything unless running nitrous or a turbo

 

[sdt354]

Yep, get them running perfect(so I like to think), then the temp drops 30-40 degrees and

Such is life with a carbureted engine.
Rov has it in a nut shell, what fun is it if ya ain't tinkering with your ride trying to get it to go faster on less fuel, have a little edge on your friends, then tell them what ya did anyway. This is blast!

 

[jfeagins]

A/F mix can also vary according to the relative humidity on the day they are set too. Set them via machine readout on a wet, rainy day, and you'll end up running the tiniest bit richer on a dryer day. Set them on the rich side of things, and the bike will start and idle, with a slight lope, on a cold morning and require lots less choke to do it. Set them on the lean side, and then have to choke more and experience more coughing back til the engine is properly warmed up. Too far off, and you might experience slower throttle response coming off idle.

At least these are some of my observations based upon 27 years of owning a completely bone stock bike.