A/F screw - is this normal? By rosiemoto (Read 579 times)

[rosiemoto]

The other day I did my valve adjustment and that's all good so the next step was adjusting my Air/Fuel screw (the flathead one on the side-bottom of the carb), and it took TWO full turns clockwise from where I started, to achieve the highest idle RPM. When I tried it counter-clockwise from the starting point, it went down immediately. So I put it back, then as I did 2 full turns clockwise it slowly went from 1500rpm up to 1750rpm, and any further clockwise caused idle to go down again. This is my first time doing this in the ~15,000 miles/6 years I've had the bike so I really didn't know what to expect. My bike was running fine before the A/F adjustment. Is that normal to take the 2 turns?

Clockwise is making the mixture more lean, right? So I'm being paranoid if I made it too lean, don't want my engine to burn out, but I did put it right where it was the highest idle so I should be good...? I revved it easy/hard a few times on the center stand and I couldn't really tell a difference, but I did notice it seemed to be revving higher with a smaller amount of throttle than before.

[Alleyoop]

Great when you get the highest RPM just turn it COUNTER CLOCKWISE about 1/8 of a turn.

You adjust to get the highest rpm by turning it 1/4 at a time then on the LAST 1/4 turn and you reached the highest turn it 1/8 the opposite to give it a tad more fuel and that will be the good setting.
Alleyoop

[rosiemoto]

Got it, so highest RPM then back off 1/8th. I actually might've/hopefully done that 1/8 turn accidentally because I turned it a half turn counter-clockwise after the idle started going down. I think. Should I go back and make sure or no big deal?

I thought my random high idling was stopped after the valve adjustment, but it just took a couple more rides to show up, even after the A/F it's idling high at one stop light, then idling normal at another. My normal idle is 1500, and by high I mean 2000. Is it a sign of anything to worry about? If it's just my bike having a personality, I'm okay with that.

So I was 2 full turns too rich this whole time. You don't seem alarmed about it needing 2 turns, so I'm guessing that isn't all that much and I'm just being paranoid.

I am really thinking after the A/F adjustment I feel some more low throttle power, as in, pulling throttle at 10-25% now makes me go a little faster than it did before; not a huge amount but it seems a little touchier.

[Alleyoop]

I took it that you adjusted 2 turns OUT from the closed position. I did not know that you had it out from the closed position 4 full turns. That would either mean you were running really rich OR you Main Jet is to small.

The thing to do is FROM wherever it is at turn it 1/4 at a time to get the highest rpm the back it off 1/8 HALF of the 1/4 turn. Reason you only adjust it 1/4 at a time is 1/4 to much or to little makes a big difference. If you go 1/2 turns the sweet spot may be within that 1/2 turn. People just want to rush these adjustment then have to go back and fart around with it somemore.

Just F.Y.I I have NOT TOUCHED my fuel ratio mixture screw going on THREE years. Once you set it especially in your are where it is mostly hot you should not have to mess with it unless something is out of whack like valves or air leaks.
Alleyoop

[rosiemoto]

Oh no, I meant I turned it 2 turns from where it began. My question was in other words, "does 2 full turns mean it was way out of adjustment?"

Now I understand you need to know how many turns from closed it is. The only thing I can tell you so far is, the screw was JUST sticking out of the thing around it, then after the first half turn clockwise, my big flathead couldn't touch the screw anymore... the screw was now inside and flathead was too wide to fit in. I managed to continue by ducktaping a straightened paperclip to the screwdriver and worked it until I got it turned enough. It was tough to do, but I got it!   I have a couple better tool ideas for next time, but seriously the bike's FRAME is in the way (again lol), so I can't fit regular screwdrivers in there.

What I'll do is I'll take it apart again and close the screw completely, then back it up 2 full turns as a baseline and from there go 1/4 turn at a time in whatever direction raises RPM, then 1/8 counter-clockwise when I hit highest rpm like you said. This way I can tell you exactly how many turns from closed I'm at.

[Alleyoop]

Ok if the screw was sticking out from the inclosed slot then it was out to far TO RICH. No need to do all that if it is running good DO NOT FIX IF IT AIN'T BROKE is what I say

[rosiemoto]

I went out and redid it just to be safe, and also closed the A/F screw all the way and backed it out twice and went from there as a baseline. So from that baseline I went counterclockwise about another 1.75 - 2 turns to reach highest RPM.

My idle was set at 1500 rpm during the adjustment. Here is what some different positions did:
2 turns from closed was too lean - idled 1200 rpm
4 turns from closed idled 1500 rpm, highest rpm around here.
5 turns from closed idle started going down again

So according to that my main jet is too small you said? Is that a big deal? It's still running smooth and good through all the throttle range, but I might look into the jet later on if it'll make a decent difference in performance or something?

[Alleyoop]

It is not the MAIN JET it is the PILOT JET, 4 turns out means the Pilot jet is one size to small is all, but if it runs good and smooth no need to tear the carb out and see what size pilot jet is in there just to get one 1 size bigger. So your good performance will not get any better or worse.
Alleyoop

[rosiemoto]

Thanks for the help Alleyoop! Glad this is finally all done, valves and all. I feel like my scooter is happier.

[Alleyoop]

YEAAAAAAAAAAAAAAAAAAAAAA!! Now get out there and enjoy riding.

[olivertwisted]

You GO girl! That's an ORDER!