turns?

ok,let me try this.i have v/h header,pod filters,and put 120 main jets and 17.5 poilt jets.what i need to know is on the air srews on bottom of carbs,how many turns out?stock carbs say 1 1/8 turns but what about now that i rejetted carb.thank u guys for and help.

i heard 3/4 out from lightly seated...to start...thats what my 900 /29 smoothies/pods/supertrapp loose packed....with the same jetting uses and is cool...

b.tracy79kz wrote:

ok,let me try this.i have v/h header,pod filters,and put 120 main jets and 17.5 poilt jets.what i need to know is on the air srews on bottom of carbs,how many turns out?stock carbs say 1 1/8 turns but what about now that i rejetted carb.thank u guys for and help.

These are mixture screws.
Turning "out" enrichens.
Turning "in" leans.

Start with 1 1/8 turns out on each screw.
Tune individual screws for best low idle.

If exhaust pops on deceleration, indicates pilot circuit too lean, so turn each screw out 1/8 turn whereby richer pilot circuit may reduce or eliminate exhaust popping on deceleration.
If popping persists, turn out another 1/8 and test run again.

Good Fortune!

b.tracy79kz wrote:

ok,let me try this.i have v/h header,pod filters,and put 120 main jets and 17.5 poilt jets.what i need to know is on the air srews on bottom of carbs,how many turns out?stock carbs say 1 1/8 turns but what about now that i rejetted carb.thank u guys for and help.

The motor might like anything from 1/4 turn to 2 full turns out. Baseline them at 1 turn out and work from there. As Patton already said, they are fuel screws, not air screws so don't force them hard closed.

Larry C

1 1/4-1 1/2 is generally good starting point

wow lots of answers.lol ill start with one and 1/4 out.thanks.

3/4 base and 1/4 out from there..not 1 1/8 and out from there...you'll see

having thought about it for a few more hours ,my memory as it is these days...i may be wrong ...i will check by counting my current turns, 3/4 from seats i think now,...running it for a good varied rip for a few miles and back and then try 1 1/8-1 1/4 tomorrow...so if i have them at 3/4...and then change em to 1 1/4 could it run the same??would i be able to tell without gauges?just from running the bike

will this be evident in a carb sync or apparent as i try and sync with a 4 dial sync tool?

how is this possible?

just curious...and where in the running of the bike will i detect the change from 3/4 to 1 1/8 or 1 1/4..idle....just coming off idle...part throttle ..open throttle...all over the range?


serious question...not playing with your guys answer earlier....thanks Craig

Dealing with this same issue right now. I just rebuilt the carbs on my 78 1000, with stock VM26's and installed 117.5 mains, and 17.5 pilots. I raised the needles one notch. I am running stock airbox, paper filter, and Vance and Hines 4/1, with no baffle. (Harley boys get away with it, and it sounds soooo good). I started at 1 1/2 turns out on the idle screws. Rode it for about 25 miles, and checked the plugs. Tan insulator, and about half the ground strap tan, the other black. I noticed that steady state 25mph cruising would begin to load up after a few minutes. The exhaust would go from a nice growl to Waaa-waaaaa-waaaa, and it just felt like a dog on the bottom. I turned the idle screws in 1/4 turn, and it is much crisper now. I will continue to lean out the idle today, until it starts to stumble, back them out until it revs cleanly under a load (Nooo driveway rev-tuning, please), and call it good. Long story short, small adjustments to the idle mixture have a big effect on low speed performance, especially with no accelerator pump to "cover" your sins. Not trying to jack your thread, just thought I'd reply, as I am in the same boat, with a similar setup, and think I have found a solution. Happy tuning!

There is no magic "number of turns out" that all the carbs should be set at. They are all slightly different, just like cylinders.

With pod filters, I've found that idle mixture screw settings are generally farther off than with the stock setup.

There are specific compatible positions that the mixture screws can be tuned to, depending on the users desire.

@ idle, there is a mixture screw position that permits the most power/highest rpm for that cylinder, and the ideal position for best fuel economy. Just beyond these points are the "too much fuel - stumbly", and the "too lean condition - popping".

Just find those positions by turning the screws in/out until the bike starts to stumble a either extreme, then pick a "number of turns" point in between, depending on what you want. Lean/rich...

After you find the actual drops, and set them all by this method, you will find that all the screws are in a slightly different position, but the bike will purrrr and perform much better at low speed/small throttle inputs.

At this point, you can start turn them all in/out X turns to affect the overall performance.

Best of luck!

that really makes sense,i hope i can get it closest with that set up......i left the house for a 150 mile ride this morning and had tried the 1,1/4 setting before leaving ...it took a second to run into trouble because my canyon is all downhill and mostly off throttle for a mile...when i got to the country highway and merged to flow along at partle open with 55-60 traffic,stumble...rough constant stumbly and it was not really wanting to pull us plus sized folks up a hill with oomph unless reved hard...i pulled over at seca and turned em back to 3/4...way better but started acting like it was stumbling at 1/8 throttle when the bike was catching up to traffic and we would settle into a almost closed throttle for the freeway....at santa cruz i tried a full turn...at the mountains a 1/2 turn....all gave different crispness at idle and coming off idle and at full throttle the smaller settings were the best....but it was still touchy and loading up at almost closed throttle coming back up my canyon catching traffic and letting it settle to a trot ...it either wanted to idle or be getting reved up....each time i changed turns i also had to fiddle with the idle set screw at a few stops signs till it would idle again on it's own....fun ride but i wanna get it better...cruising along at near closed throttle felt like the timing was off and was annoying sometimes...thanks for the tip i will try that tomorrow ...peace Craig

When cleaning 29 smoothbores, the small air jet BS30-97 is sometimes easy to overlook.

Good Fortune!