Just how do you adjust mixture screws using a tachometer?

[DClark]

I have a dwell gauge/tachometer that I’d use.
Is the procedure:
Set idle at 800rpm
Turn screw out until idle drops, then turn another 1/4 turn in?

[buffalobill]

Sounds 1950s tech.
I use a Colortune

[DClark]

What about the people who say they can only see the flame at night in garage?
At night, my garage gets pretty cold .

[buffalobill]

What about the people who haven't got enough food?
Watcha gonna say to them?

[Parts man]

Set idle to normal 11 1200..turn mix screw in until you get a rough idle then out to highest smooth idle. ..repeat on other carbs...then readjust main idle if needed (this is how I do it)

[DClark]

So, I turn it in ( make it lean) until idle gets rough, then turn the other direction
( make it rich) until I get highest idle, and if it dips slightly, I just turn it back by a 1/4 turn?

[92xjunker]

[Parts man]

Yessir

Of course this depends on how clean you're carbs are...I never could get mine set right until I took them apart and cleaned them

[DClark]

Bike has nice idle, runs nice and pulls hard as I wanted to go on a bike with 10 year old tires.

[Parts man]

My bike has 10 year old avons...I have new contis gotta get them put on

[DClark]

I got one azarro on the front that is almost at the wear bars and is ten years old. The rear looks like new and is nine years old, but it feels hard. Hate to pitch it but it just plain doesn't feel like it should. The bike feels like it is riding on solid, no air rubber.
I'll be replacing them with new Lasertecs while sending out forks and shock for rebuild/new springs.
In the mean time, I want the motor dialed in. I figured that with kerker 4-1, FP jet kit, perfect jetting, timing advancer, relays for headlamp and coils (with spark plug gap at .9mm) stiffer springs front and rear and Lasertecs tires with new improved compound, this heavy kitty should drive/ride much better than it did when new.

[Parts man]

Sounds like a good plan...but I ain't playin around with 10 year old tires

[Kreylyn]

So, I turn it in ( make it lean) until idle gets rough, then turn the other direction
( make it rich) until I get highest idle, and if it dips slightly, I just turn it back by a 1/4 turn?

The drop down method...

It's easier to see/hear a response from the motor at a lower rpm than normal idle, so I do suggest turning it down to around 800. If the carbs are clean, the bike should idle at that rpm and stay running. If not, go as low as you can for the process.

You have the turn in and turn out correct. The point is to find the points the engine reacts to lean and rich.

The key point on this is noting the starting point and number of turns. You work out the final setting by doing a simple math.

So lets say you start at 2.5 turns out. You turn in 2 turns "lean" until the motor stumbles.

You have your first number... .5 turns out. (see the simple math process here?)

Turn it back out (remember your already at .5 turns out) and the engine should start to run better. Continue out until it stumbles again. Lets say you go to 3.75 total turns out (including the .5 you started at) and it stumbles again. You now have your 2nd number.

.5 & 3.75 are the 2 numbers you would be looking for in my example.

Your final setting is directly in the middle of those numbers. It's not turn back 1/4 turn, it's turn back to half way between the 2 numbers. The math on that is still simple... 3.75 - .5 = 3.25. 3.25 / 2 = 1.625.

.5 starting point + 1.625 or 1 5/8 turns = 2 1/8 turns.

So in this example, the final setting would be 2 1/8 turns for that specific carb/cylinder combo. This will likely be different on every carb by just a hair, but not necessarily and isn't a problem if they all end up the same.

Also note that every carb you adjust, it's very likely to also have an effect on the rpms... so you may need to or want to adjust between each one.

Krey