Throttle body sync set screw

[REO Scorpio]

Random question for you experienced mechanics:

The first year I had my bike, I bought a carb tune and synced the carbs even though I only had 2000 on the clock.

In my mechanical infancy, I may have slightly moved the number 1 screw. I moved it back as best I could to the spec in the manual (21.5 IIRC) and then synced the others.

What would the process be to reset that to factory? Would I need a flowbench or anything? As the others seem to be affected by each other, is there a standard to reset number 1, like close the others, set 1, then sync? Just seeing if anyone has a definitive answer/explanation or if someone knows what the dealer would do if I took it in for some thee things.

Have always been curious, finally decided to ask. The bike doesn't run horribly, but since I did it early, who knows if I had a benchmark.

Thanks for any info,

Scorp



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[Red Wazp]

You should use #3 as the base for the others. If the bike runs smooth don't worry about it.

 

[REO Scorpio]

Strange. On page 3-7 of my service manual, it says to use #1 as the standard and adjust others to it.

When it gives the intake pressure, 29 kpa, 8.6, 218, etc., I assume that is for #1, but as they all adjust when you move any one, I'm unclear if there is a standard to set that (all closed first, all opened, etc) as it will change as soon as you adjust #2, 3, etc. Just trying to see if I can "go back" and truly start over from year ago.

Scorpio





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[foxbass]

Ok, this how I see it having done the job only yesterday.
I took the right hand (as you sit on the bike) long tube as my starter, but it shouldn't matter too much. What you need though is a vacuum gauge to hook up to it. The standard setting is 8.5in/hgm at idle. Some guys with aftermarket cans up it to 9 or more to stop them popping on over-run.
If you hook it up and the needle jumps around kink or partially clamp the hose until it settles. Adjust as necessary. Thats all you need the gauge for.
Once you have that TB sorted leave it alone and use the balancer to equalise the others to it, preferably one at a time leaving the balancer connected to the first line. Remember not to adjust the first one again. Its done. Don't worry that the levels change as you adjust, keep in mind that all you are doing is balancing.
As you proceed, blip the throttle gently a few times and let levels settle back to re-check. Depending on how far things have got out, you may need to re-set the idle screw to around 12 - 1300rpm at each stage.
I found that doing TBs one at a time, I could concentrate on just one issue.
HTH

 

[FinalImpact]

FWIW: Once you hit the sweet spot on all carbs the idle will climb when each cylinder has the proper air/fuel ratio. With this, the vacuum increase on all 4.

To lean, you get lean misfire and idle drops/gets rough. Same for being to rich but being too rich is more forgiving than being too lean. Running to rich is hard on the CAT and stinky, but it will pull better when cold from low RPMs off the line. Idle will also drop if too rich as the AFR is incorrect.

If you find yourself in a position where one or any adjustment seems to do little to the sound, vacuum or smoothness, get a visual sense for how far you can move it in both directions before anything changes in both directions and split the difference centering the # of turns in/out.

 

[REO Scorpio]

Ok, this how I see it having done the job only yesterday.
I took the right hand (as you sit on the bike) long tube as my starter, but it shouldn't matter too much. What you need though is a vacuum gauge to hook up to it. The standard setting is 8.5in/hgm at idle. Some guys with aftermarket cans up it to 9 or more to stop them popping on over-run.
If you hook it up and the needle jumps around kink or partially clamp the hose until it settles. Adjust as necessary. Thats all you need the gauge for.
Once you have that TB sorted leave it alone and use the balancer to equalise the others to it, preferably one at a time leaving the balancer connected to the first line. Remember not to adjust the first one again. Its done. Don't worry that the levels change as you adjust, keep in mind that all you are doing is balancing.
As you proceed, blip the throttle gently a few times and let levels settle back to re-check. Depending on how far things have got out, you may need to re-set the idle screw to around 12 - 1300rpm at each stage.
I found that doing TBs one at a time, I could concentrate on just one issue.
HTH

That is basically what I did the first time, only I believed I used the left side long (pink stripe) as my #1 and set them to that.

I'll take another crack at it this season and see if they have changed at all.

Thanks for the help, guys.

Scorp