Hey all,

I'm sitting here preplanning the things I'll attempt to do to my Sporty closer to spring, and on reading the excellent instructions on performance tuning (http://www.harley-performance.com/ha...FQUUKgod3HhFOQ), I come up with hopefully a simple question:

How many turns out can you perform to the mixture screw without it coming out? (Which I believe leads to installing bigger jets). I'm a fairly decent puttering mechanic, but losing the internal springs behind that screw sounds a bit beyond basics!

And the reason for me touching it at all is carb farting (lean). Moreso after blowing money on the K&N Kit.

Thanks!
Bill

 

do you mean falling out???probably 5-6 whole turns...but you should never have to go that far..if you turn it out another whole turn (maximum) and it does not fix the problem, it never will... just give the screw a 1/8 turn and see if it gets better, if not do it again, keep doing it until the idle gets worse then turn it back in a 1/4 turn or almost until it starts to slow alittle...just never screw the screw in tight ( it will mess the screw up)

 

what mrfisker said is right,if you need a starting point turn in all the way then come out
2 1/2 turns and work from their,you might have trouble getting it right where its so cold.

 

This is just my experience:

Most Sportsters come with a 42 pilot jet as stock equipment. I like to remove the 42 pilot jet (also called a slow jet) and replace it with a 45 pilot jet and go 2 full turns out from lightly seated on the mixture screw and play around from there. There are lots of "googled sites" on the way to adjust the mixture screw or low speed screw.

I have found that this is a good place to start with stage 1 (pipes / slip-ons and a hi-flow air filter). The stock carb has a "plug" covering the mixture screw which needs to be removed if it has not been already. Watch this video - the guy covers most aspects of a Harley CV carb even though he is putting it on another bike. You can figure it out.

http://youtu.be/CXKUT9HeRnM

YMMV

 

Looks like you have stock pipes, but if you're like the majority, the baffles are gone. If you don't have baffles, you'll need to go up a size on the low speed jet to stop the farts; might even have to just with the K&N. Even with the baffles, it'll probably run better with the jet change. I have a K&N style filter element in the stock filter housing, and usually run with baffled mufflers (have both), and it runs smoother with the larger jet, regardless of muffler used. You take a small performance hit when you remove the baffles, though. I didn't think it was difficult at all to do the jet change, plenty of how to articles and photos on the internet and elsewhere on this forum.

 

I really appreciate the advice guys. And great video Nailz; it really eases my nerves!

And yes, they're stock pipes. I haven't touched them since I got the bike, but I suppose I should look to see if the baffles are there. And I was already leaning towards putting in a .45 slow jet.

Cheers!
I'll give a report and pictures when I get at it in April.
Bill

 

Hi HalifaxBill, you should only need to adjust the idle mixture screw and that should take care of your carb farts. Also replace your intake seals, if that hasn't been done then yet then they are hardened and leaking air ...leaning out one or both cylinders. I wouldn't bother replacing jets, get an N65C needle, from an '88 1200C non-accelerator pump CV carb, shim it up about .040 (2 washers) and you will properly richen up your entire throttle range. You will be pleased with the results.

 

On my 883, I opted for the jet change, quick and easy. I've done needle tweaks on older bikes, but don't consider it a job for someone not comfortable with taking a carb apart. That diaphram on the Harley carb can sometimes be a challenge to get back on right (stiffening it up in a freezer might help). The needle change is supposed to improve everything up to wide open, but on an 883 I don't think anything less than a 1200 kit makes enough difference to be worth the cost or effort; it's a pretty sedate bike, good for an old geezer like me. Intake seals get blamed a lot, but they're easy to check; just spray some wd40 around them while the bike is running; if there's a leak, should get a momentary rpm change as the oil stops it.

 

The rpm change is due to the engine burning the wd 40 sucked in through the air leak. You can start an engine with wd40 even if it is not getting any gas, good starting fluid.

 

That makes sense. I wasn't even thinking about that; long time ago, when I worked on a big variety of things with motors, the quick and dirty trick to find an air leak around a carb was to squirt motor oil on it; the thick oil would block the leak for a few seconds and you could usually see where it got sucked in. Some guys used water, but I never liked to spray water on a hot engine; besides, it sucked through so fast it was hard to see where the leak was. Those were big dirty industrial engines; a little oil just freshened the grime, but I use WD40 on something I want to keep clean. If I ever run out of starting fluid, I'll try WD40; didn't know engines could run on it, thanks for the tip. Never too old to learn.