RoyalStar Carb Trouble

[Curtisb0671]

I recently purchased a 1996 Yamaha royal star after replacing the fuel lines the petcock cleaning the tank, replacing the fuel pump, replacing the fuel filter, rebuilt the carburetor, replaced the pilot screws, replaced the manifolds ,any suggestions on setting the pilot screw back or can anybody tell me how would be the best way to do it thank you very much for any help you can give me.

[Freebird]

I don't know an easy way to do it.  I think to really do it properly, you need an exhaust gas analyzer.  I think I've seen that a good starting point is about 2 1/2 to 3 turns out.  Some people who are pretty good can then listen to the RPSs to get it very close.  I'm actually thinking about the mixture screws though.  Not sure if that is what you mean.

[Marcarl]

If what you mean is the mixture screw, it's not so hard as you might think. 2.5 turns out gets you in the right area.

First you need to balance/sync the carbs, then set the mixture screws, back to sync the carbs and then re-set the mixture. For this you will need at least one vacuum gauge, but it's much easier to sync the carbs with a carb sync tool. For setting the sync all carbs need to be drawing the same amount of vacuum so that will ensure that they all are carrying an equal burden of weight when it comes to torque or HP.

The idle mixture screws will and can adjust the fuel mixture that goes into  each cylinder at idle, and once off of idle that idle circuit in the carb has less and less effect on the whole mixture situation. Fact is that once over 1500 rpm you wouldn't notice any difference in the running of the engine if you did adjust the mixture screws at that speed. Now if the idle circuit is set too lean you might find that response time from idle to running will be slow or it may hesitate, too rich and it may cough a bit to get going, but as long as you have it in the right area mostly you'll be quite happy. When setting the idle mixture with a vacuum gauge you will be looking for the highest possible vacuum at 900 rpm, not any faster or you will be into the running circuit and not much slower either or the vacuum won't be stable. For each carb the idle must be set back to or up to 900rpm.

Hope this helps