Vanguard tunning

MrNeon

*Ok guys, back at it again. I installed the carb spacer on my 21/23 hp motor as well as did some maintenance and fit the newer sealed air cleaner. I got as far as adjusting the carb/motor to run with the new carb spacer and quit there. Some things I have encountered so far are a higher RPM at idle. I have the idle screw all the way out and still its idles too high to shift. I am going to assume that the spacer is the reason for this but not too sure. I am presently adjusting the air/fuel mixture screws trying to get that sweet spot so it runs better. It does help with the idle but I think it may suffer elsewhere in the rpm range? It is a 2-barrel Nikki carb, but it does not have the emulsion tube. I took it all apart and the jets are there but I do not know if there will come out since I tried to remove them but felt I had to break the screw to get them to release. I gave up on that idea. I just have the idle screw and the 2 air/fuel adjustments to work with. I started out by turning the air/fuel screws all the way in and then back them out about 1-turn to start. It seems to run pretty decent there. When I went for a few test drives I notice a great improvement over mid range and higher rpm for throttle response. I am assuming the carb spacer is the reason.
So, I think I am heading in the right direction. I would like to hear any suggestion as to getting the idle down respectfully so that I can shift easily. It seems the air/fuel screws are the only way but I don't want to lean out the carb. I did installed new plugs, Autolites. My old ones were NGK's and were black/soot from running too rich. The new plugs are white and dry right now, so I know I am lean.
As for the air cleaner. I got it to fit good and it does work great, but I want the carb set first. I still have to plumb a 2" hose to the intake of the air cleaner for fresh air. Few others things as well.

Overall so far with the carb being not set up just yet, the spacer with the cut out divided seems to make the motor run better and more responsive at mid and higher rpm's I feel like I got more pedal on top end, not that I needed it but its nice to know! The new plugs helped as well. I have the timing key, cam, etc.. all the goodies. So I am happy so far.

BGW

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Shepard

High uncontrollable idle happens when the idle screw on the throttle is out of synk with the air/fuel screw. If you have the throttle open to far the carb is not working the idle circuit like in the top picture. It's operating the transition circuit Like in the bottom picture. You said you have the screws backed out so it's getting even more gas.

Turn the air/fuel adjusters close - magic mark dot at 12 o'clock on the screw face. Open the air/fuel screws 1-1/8 turn watching the mark on the screw face. Close the throttle all the way backing out the idle screw -- turn the idle screw in till you can see it just barely open the throttle. Too bad its all mounted cause you should set the idle screw by sight on the bench.

It becomes a dance between the idle screw and then the mixture screws. Once it's warm and tries to idle --- if its to high first close the throttle before trying to adjust the mixture. Turn the screws 1/8 turn at a time so there's no radical changes.

Attached Images

IdleandTransitionCircuit.jpg (120.4 KB, 0 views)

panteramatt

Following as i have the same setup but my plugs are black. If I lean it out it stumbles on acceleration for a stop.

Shepard

Are you saying your idle is high -- what is the problem your experiencing?

MrNeon

OK, I messed around more tonight and may have found an issue with the throttle. After turning a bit the air/fuel screws seems to be about 1/4 turn out give or take. I did one side at a time while it was running at idle...I turned one side in until it nearly stopped, than back it out till is smoothed, repeated the other side. I did not have to go maybe an 1/8 turn at most to get it to smooth out each side. I am definitely not out one full turn nor 3/4 of a turn. Idle is down from when I first started and I can shift into gear without forcing it or the cart wanting to jump. Still need to do some test runs but its dark now and I have no lights put on yet. I also installed a set of billet push rods and adjusted the valve lash to .005 and the engine is much quieter and smoother.

As for the throttle, I may have a return spring that is worn and not strong enough to pull the throttle back. I modified the original throttle off the Vanguard motor to work with the Yamaha pedal and for a few years it was great but then I did not have a carb spacer as well as polished the intake and carb spacers out. So the spring may have weakened enough not to pull it back. I noticed when I manually played with the throttle, I have just a tad more recoil that would idle down the motor. I could be wrong but I may look into a different throttle set-up as well from CCP if they have a kit. I think the throttle comes in on the right side where mine is on the left.

Shepard

I'm not sure if this makes sense or you'll understand. The mixture screws DO NOT CONTROL THE IDLE SPEED. They control the mixture at an idle rpm. The throttle controls the idle speed.

MrNeon

I get that. That is why I think it may be a linkage problem since the idle screw is backed out not touching the actual throttle plate. I also wonder if I have a small air leak in the carb. I took it apart and cleaned last week but I did not mark the butterfly's to where they were originally mounted. When i rebuilt the carb everything went back together fine and fit great. Given they are beveled, is it possible they were seated to their particular side thus not closing properly/ or closing but not seated when I may have installed them on the opposite side?

Shepard

The butterflies may be offset say if you tightened one then installed the second. I would loosen both sets of butterfly screws -- hold the throttle shaft closed and carefully tighten them again. I don't think it matters which one goes in what bore but they need to be centered properly for them to close all the way. Also back off the idle screw so you know they are centered and close tightly. I had a little trouble with a single bore carb and getting it to close right.

Shepard

Here's another picture that shows the idle and transition circuits. You can see that if the throttle is open too far no amount of turning the idle mixture will change the idle speed because the engine is being fueled by the transition circuit. This is the main reason for high uncontrollable idle. Yes air leaks - high fuel pressure - poor float needle and seat will contribute to a high idle issue but adjustment is the first thing to check -- also the cheapest.

Attached Images

Mixture.jpg (510.8 KB, 0 views)

panteramatt

Nope my idle is fine its just my plugs are black and sooty