Author Topic: A/F screws adjustment question. (Read 7046 times)

ptitza · « **on:** January 31, 2006, 02:18:49 PM »

How exactly I'm supposed to do that on a B12?
I've done it on my Vulcan 500 few times, and it was pain in the ass because of a hot engine and small clearance between carbs and starter.
I`ve checked this issue today on my B12, there is more clearance, but reaching carbs 2 and 3 will be a major problem when the engine is hot (it was even when the engine was cold).
I do know that there is a tool for that, but is it possible to get one at around $20(less is better)?
Or is it some way to do that without burning your hands or removing the carbs each time you want to turn the screw another 1/8?

rider123 · « **Reply #1 on:** January 31, 2006, 05:08:42 PM »

Well for the one and two cylinder its not too much of a problem as there is a rubber sheath that goes around the electrical connection to the starter motor that you can rest the edge of your hand on and I just use a 3 inch long drill bit with a slot head on the end and a dentists mirror and it works fine. The only real one thats a problem is Number 3 cylinder as you have to put the edge of your hand on the hot tranny case. But if you get a rag and fold it up and make a little bed in there for the edge of your hand you should be able to get in there no problem to turn the screw. The outer screws are a no brainer. You can also use a small makeup mirror you get in the dollar store for a buck to see where your screws are.

If you know where you need to turn to and you have a rachet set you can make your own 90 degree angle screw turner with the adapters in most rachet sets. You just need a small enough driver that a hexagonal screw bit like on most multi screw drivers will fit in there and you can screw the screws in one direction only.

If you want I'll post some pics if you like of my Free way of adjusting mixture screws. Because of the horrid stock jetting I've had lots of practice!!!

ptitza · « **Reply #2 on:** February 01, 2006, 10:53:59 AM »

Well.
I`ve found another solution to the problem.
Got myself a $4 a flexible screwdriver extender. Does exactly the same job:)

Bazza · « **Reply #3 on:** February 20, 2006, 03:14:25 AM »

I found that if you adjust them enough, you will burn your fingers enough times that you will not feel anything on future adjustments!

smooth operator · « **Reply #4 on:** February 20, 2006, 09:22:11 PM »

I'm going to try turning them in a 1/4 turn the next time out. I have notes where they are now in my sv manual(3 trns) and I'll do it while its cool. And try them @2 3/4 out. runs great,but she sure is a thirsty little devil. I hope it doesn't starve the low end too much. I'll find out if this ice and snow ever melts.

rider123 · « **Reply #5 on:** February 24, 2006, 08:10:07 PM »

The clymer guide seems to be out of wack. I tried 3 turns out and it was horribly rich on my 2G B12. I would try 2 1/2 and go from there. I'm at 2 1/2 turns out now and it seems fine. Remember it's winter so you're going to be using a little more gas to be running correctly it will need to lean up when it gets hot.

smooth operator · « **Reply #6 on:** February 25, 2006, 08:55:23 AM »

Actully had a afternoon ride the other day. turned mine in to 2.5 out and seemed alright. Still have alittle low end stumble under 3k. Only went 40 miles though,the wet spots turn icey as the sun starts going down. (my Feb. ride)
I'm trying to sqeeze out some more mileage.If the low end bothers me when I have a chance to ride some more,I'll go up in the piolots again then readjust the fuel screws.
One of these days I'll have it all figured out.

rider123 · « **Reply #7 on:** March 01, 2006, 03:43:19 PM »

It may be the weather too, winter is not the greatest to tune the bike. If you want to compensate slightly, turn the screws out just a smdigen like 1/8th or under out. That way it should give just that little bit of edge. Also in the winter it take a hell of a long time to get to full hot so you may still be slightly cold. Ride for and hour or so then see where you need to stick the screws.

A good way to test is let the bike sit still and idle inyour driveway for 5 to 10 minutes before you take off so you know for sure your at 100% full hot.

How I set my screws is this way:

Let the bike idle in your driveway or stationary for 5 to 10 minutes untill full hot.

Let the bike idle with slight throttle inputs(under 1/8th throttle) every once and a while say up to 3K rpm, blip the throttle lightly occasionally as well. Stop the engine and check the plugs, since the plugs don't lie. Since your idleing and using low throttle rpms your running on the pilots only and this will help you tune the mixture screws. Also if the pilots are perfectly setup you may have to make them slightly richer by 1/8th of a turn or less turns out to cure a stumble as the bike will need more gas to move than just idleing there. Ideally you would want the mixture screws to be a slight smidgen rich from lean idle.

As I said the Clymer guide seems off a bit they recomend 3 turns out which is too rich for the stock setup. 2 1/2 seems a little closer to the mark at least on my bike and a couple of guys bikes on this forum.

Bazza · « **Reply #8 on:** March 06, 2006, 03:34:54 AM »

I have my A/F screws out to 3 3/4 turns with larger pilot jets (17.5).

(I also have an Ivan's jet kit & modified air box)

The best tip I can give you is to start increasing them out 1/4 turn at a time until you get the best idle. All the a/f screws will help you obtain in a beter idle & low RPM range. I would not go past 4 turns out as the screws become less accurate at metering past 4 turns. If you need to go past 4 turns to obtain a good idle, you need to install larger pilot jets.