A/F Screw: In=Lean, Out=Rich???

[decdrummer]

I have the bike idling wonderfully, just when I blip the gas it bogs down, and I have a slight hanging idle. I have checked for vacuum leaks, and believe it is an A/F problem, but I can't remember if IN=LEAN, OUT=RICH???

If this is correct, should I richen it up or lean it out? The exhaust smells slightly of fuel.

Thanks guys!

[Kreylyn]

I have the bike idling wonderfully, just when I blip the gas it bogs down, and I have a slight hanging idle. I have checked for vacuum leaks, and believe it is an A/F problem, but I can't remember if IN=LEAN, OUT=RICH???

If this is correct, should I richen it up or lean it out? The exhaust smells slightly of fuel.

Thanks guys!

If the idle is hanging, it's lean.

Smell doesn't tell you anything... you will smell gas anytime fuel is not buring, and that is anytime the air/fuel mix is not correct. Lean doesn't fire, rich doesn't burn it all...

You will also smell gas since the fuel system is an "open" system... your bike is gonna smell like gas as heat forces fuel to evaporate from the carbs out into the air.

In = less fuel
out = more fuel

Krey

[decdrummer]

Thank you so much Krey! Should I start by going out .5 at a time?

[decdrummer]

Ok I'm thoroughly confused now. According to Carbs 102, "You will find that on most stock bikes, 1.75 is all you need. With jet kits, 2.25 seems to be about the best number (More air = more turns out!)"

I've been at 1.75, then 2, then 2.5, then 3 turns out. When I blip the throttle the engine dies, and I've had to change the spark plugs out due to them fouling. Is there a definite of how many turns out I need to be? (stock air filter and D&D Exhaust)

Another question: Do I have to re-sync after adjusting A/F screws?

Thanks!

[Kreylyn]

Ok I'm thoroughly confused now. According to Carbs 102, "You will find that on most stock bikes, 1.75 is all you need. With jet kits, 2.25 seems to be about the best number (More air = more turns out!)"

I've been at 1.75, then 2, then 2.5, then 3 turns out. When I blip the throttle the engine dies, and I've had to change the spark plugs out due to them fouling. Is there a definite of how many turns out I need to be? (stock air filter and D&D Exhaust)

Another question: Do I have to re-sync after adjusting A/F screws?

Thanks!

Okay, first...

According to Carbs 102, "You will find that on most stock bikes, 1.75 is all you need. With jet kits, 2.25 seems to be about the best number (More air = more turns out!)"

This is just wrong, flat out. For some reason, it's not been changed or updated... but it's wrong.

1.85 turns is the factory OEM setting from 20 years ago, when the gas was not mixed with todays additives and alcohol. Second, more turns does NOT mean more air, that is just wrong. More turns increases the fuel that will be added to the mixture. The only thing that increases air is changing the filter/airbox to non OEM setups, or having air/vacuum leaks, both of which will lean things out further. That means MORE turns out on the A/F screw to compensate.

If your not seeing a major change in how the bike runs between 1.75 to 3 turns out, then your pilot circuit is dirty, and adjusting the screws won't help at all. Plugs will foul out simply by not running the bike long enough for them to self clean when the engine reaches full running temp. Multiple starts and stops on a colder engine will foul the plugs.

You should definatly start at 2.5 turns on the A/F screws. If the bike won't idle properly at that, then your carbs are dirty, you have an air/vacuum leak, the carbs are not assembled correctly, or you have additional contributing factors like an electrical issue with 1 or more cylinders... bad plug(s), wire(s), coil(s), etc...

Krey

[decdrummer]

Thanks for clarifying that Krey, I'll take note. I will reset to 2.5, and let the bike idle until it reaches full running temp, then see if any problems persist. Thanks again!

Just read in the manual that Main jets 1 & 4 are 115 and Main jets 2 & 3 are 112.5 (I'm assuming this is the emulsion tube jet?). When I dipped the carbs I didn't keep these together. Is it possible if I accidentally switched these main jets around it would cause a running issue?

[Kreylyn]

Thanks for clarifying that Krey, I'll take note. I will reset to 2.5, and let the bike idle until it reaches full running temp, then see if any problems persist. Thanks again!

Just read in the manual that Main jets 1 & 4 are 115 and Main jets 2 & 3 are 112.5 (I'm assuming this is the emulsion tube jet?). When I dipped the carbs I didn't keep these together. Is it possible if I accidentally switched these main jets around it would cause a running issue?

Clarification on terminology...

The long tube the needle goes into is the "Needle Jet" but commonly refered to as an "emulsion tube".

At the bottom, the "Main Jet" screws into that.

The main jets are the sizes it's talking about. Not having the right size main jets will cause problems at higher rpms primarily, but can have some minor effects on the idle.

While it may contribue to some of the issues your seeing, I don't think those alone being mixed up is causing all the issues. The A/F screws should still make chagnes to how it runs even with the mains mixed.

I would go back and check those main jet sizes to make sure they are correct. It is a nessasary things for higher rpms for sure. The size is on the bottom flats around the hole.

Krey

[arsenic]

Those main jet specs he listed are correct. There is a slight terminology difference with 98+ carbs. They don't have an "emulsion tube". The have a needle jet, which is the little silver collar thing that protrudes a little into the carb bore. Then below that the the needle jet holder. That screws into the float bowl area and has an o-ring on it. Than the main jets screw into that. You're correct 1 & 4 = 115, 2 & 3 = 112.5

[Kreylyn]

Those main jet specs he listed are correct. There is a slight terminology difference with 98+ carbs. They don't have an "emulsion tube". The have a needle jet, which is the little silver collar thing that protrudes a little into the carb bore. Then below that the the needle jet holder. That screws into the float bowl area and has an o-ring on it. Than the main jets screw into that. You're correct 1 & 4 = 115, 2 & 3 = 112.5

bouncing around too many threads, forgot his was a post.

Krey

[decdrummer]

Ok cool. On a good note I'm getting the tag for the bike tomorrow, but before I get frustrated I'm going to stop, ,and completely redo/recheck/reclean/recheck everything tomorrow when I have a clear head. Thanks for all the help guys!!!!!