Carb jetting question : V-Twin Forum: Harley Davidson Forums

SlowRider · 06-07-2007, 07:38 AM

'03 Dyna Lowrider. Stage 1 since new -- slipons, airfilter, and the dealer rejetted by switching the pilot to a 48 and shimmed the stock needle with 1 washer. They also adjusted the idle mixture, which was at about 2-1/8 turns. I've always had some lean coughing and carb farting, expecially when it's cool out, and it always seemed to need the choke for a long time (15 min. or so). Aside from the coughing, it actually seemed rich; exhaust smelled like raw gas at warmup & idle and the plugs are sooty. So last night I made some changes. Took the carb apart and cleaned everything with carb cleaner. Then replaced the needle with an '88 sporty needle (no washer) and the pilot with a 46. Also added the mixture screw with the knurled knob. My thinking was that it was too rich at idle with the 48 pilot, and too lean at 1/4 - 1/2 throttle (where the coughing was) with the stock needle. I didn't start it up last night. (Too late and the neighbors already give me 'the look') I guess I'm just wondering what the collective wisdom is for what I did and if I can expect things to be better than they were. Can't wait to get home tonight and try it out.

SYCLONE · 06-07-2007, 08:01 AM

Exactly the changes i'd have made...try 2 turns out on the pilot bleed screw with the 46 slow. Start it on the enrichner....lock the throttle open enough to keep it running with the thumb screw..push the enrichner off...
after about a minute you should be good to ride off.......

SlowRider · 06-07-2007, 08:23 AM

Thanks Syclone. That's what I was hoping to hear!

SNUFFY · 06-07-2007, 01:51 PM

where di you buy the ccp fuel and air screw at ?
drag no longer has them

SlowRider · 06-07-2007, 02:45 PM

Quote:

Originally Posted by SNUFFY

where di you buy the ccp fuel and air screw at ?
drag no longer has them

I got it a while back from a place called "Custom Cycle Supply" (I think). They used to be a sponser here. They must have went out of business 'cause the web site has been down a while. Anyway the nightrider site will direct you to http://www.johnsmotorcycleparts.com/

I believe you can get it there. Hope it helps.

LoneEagle964 · 06-07-2007, 04:12 PM

Quote:

Originally Posted by SNUFFY

where di you buy the ccp fuel and air screw at ?
drag no longer has them

Jp cycles has them page 510 in my book part # 400-764

LoneEagle

murphdog · 06-07-2007, 07:16 PM

Quote:

Originally Posted by SlowRider

My thinking was that it was too rich at idle with the 48 pilot, and too lean at 1/4 - 1/2 throttle (where the coughing was) with the stock needle.

I think your thinking was right on the money, SlowRider. That should work very well for you. You can probably get by just fine with the stock 45 slow jet, not much difference between a 45 and 46. Lots of folks believe shimming the stock needle does the same thing as changing to the Sporty needle. Not.

SlowRider · 06-08-2007, 06:35 AM

Well I went for a (short) ride last night and she runs great. Not a hint coughing or that feeling that things are a little lean. Even sounds better at idle. I still need to adjust idle and fine tune the mixture. I couldn't completely turn off the choke last night 'cause the idle was set too low. Once I fiddle with that I should be good to go.

Ed Y · 06-08-2007, 06:50 AM

Be sure and get the idle set right then adjust the mixture not vice versa. You've got to keep jumping back and forth.

deanz02 · 06-08-2007, 07:32 AM

Be sure your thumb fuel screw really works. I had one on my bike and found it didn't matter where I set it as it didn't make any difference. You should be able to kill the engine ( or at least make it seem like it's going to die) by turning it in. I ended up going back to the stock screw and it fixed the problems I was having.

Mtclassic · 06-08-2007, 08:36 AM

Becareful of having your thumb screw fall out. I have read more than one report of the aftermarket thumb screw backing out on its own and falling out.

SlowRider · 06-11-2007, 08:32 AM

Bike runs much better than it did before. I adjusted idle and mixture on friday. Cold starts need choke for about 1-2 miles then off. Much less than before. Idle sounds 'crisper' if that makes any sense. No coughing or farting. Just overall runs better throughout the midrange.

Mixture screw is set to about 2-1/4 turns. Engine stumbles at less than 1 turn. Turning it out much further didn't seem to make a lot of difference. As far as the thumb screw falling out, I noticed that the barrel that the screw goes in has a small hole on the side where I can see the threads. I was thinking of putting a little blue loctite in that hole to hold the screw in place to keep it from backing out. I should still be able to turn the screw, but the loctite would gum it up enough to keep it from turning on it's own. Wadaya think?

Also, bike seems to have a little less at WOT than it did before. Maybe it's just me and it only seems that way now because of the better midrange performance. Any chance I need a 195 main? The stock 190 is in there now.

SYCLONE · 06-11-2007, 11:00 AM

The 190 main is plenty..... like you said, the midrange is correct now so going to WOT isnt so drastic of a change.

SlowRider · 06-11-2007, 11:50 AM

Thanks Syclone. The bike really does feel juicier overall. The improvement is very noticable. I really appreciate all the help from this forum. I got all the info to do the changes from reading old posts here. Next stop is a 95" kit, cams and heads (over the winter I think).