Carbs at different altitudes
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2nd Gear
Joined: Apr 2009
Posts: 6
Likes: 0
From: Middle Tennessee
Carbs at different altitudes
I would like some feedback from "Those in the know" about something that has been a pain for a while now, Carb Jetting. My 06 Street Glide seems to get hot and run very rough in hot weather, when riding slower or sitting in traffic for short times. In colder weather, it pops when slowly rolling into the throttle, even after riding for over a half hour.
Now, when I went to Bikefest in Daytona last fall, the bike ran cooler with no problems what so ever.
1st Question: is the cooler running in Florida than Tennessee an altitude/air density issue?
2nd Question: I have a stock CV carb with a 50 pilot jet and adjusted air mixture screw, aftermarket pipes and screamin eagle air filter. Would anyone try an adjustable jet needle and/or larger main jet or any other suggestions.
After four trips to three different dealers and a run on the Dyno, i still have the same problem. Any suggestions would be greatly appreciated.
Now, when I went to Bikefest in Daytona last fall, the bike ran cooler with no problems what so ever.
1st Question: is the cooler running in Florida than Tennessee an altitude/air density issue?
2nd Question: I have a stock CV carb with a 50 pilot jet and adjusted air mixture screw, aftermarket pipes and screamin eagle air filter. Would anyone try an adjustable jet needle and/or larger main jet or any other suggestions.
After four trips to three different dealers and a run on the Dyno, i still have the same problem. Any suggestions would be greatly appreciated.
Outstanding HDF Member
Joined: Jan 2008
Posts: 3,328
Likes: 15
From: Pacific Northwest
A DynoJet carb kit is what you need. The also used to make a different slide that helped throttle response. As I recall it was known as a Thunder Slide kit. I wouldn't run a CV without one.
Tourer
Joined: May 2009
Posts: 315
Likes: 1
Stay away from the DynoJet kits. A CV will run fine without dorking it up with one of those kits. Do a little reading and you'll see most "in the know" don't recommend them.
Yes temp and altitude will make a difference. The first thing I would suspect would be the 50 slow jet. That seems a tad too big for a mostly stock bike. Most are running a 46. I run a 46 in the summer and a 48 in the winter. When it's cold it runs leaner.
Did your dyno guy give you a readout showing you your AFR's from idle on up?
Yes temp and altitude will make a difference. The first thing I would suspect would be the 50 slow jet. That seems a tad too big for a mostly stock bike. Most are running a 46. I run a 46 in the summer and a 48 in the winter. When it's cold it runs leaner.
Did your dyno guy give you a readout showing you your AFR's from idle on up?
Tourer
Joined: May 2010
Posts: 350
Likes: 1
From: Floridia
If it's popping when you are rolling on the throttle, that's and intermediate circuit lean condition. You can try shimming you needle, or run the sportster needle with the narrow taper. you said you have a 50 for the idle, which does seem a bit big for a stock 88, or even for a mild 95". Most are running a 48, some even a 46. What size is your main jet, and how do your plugs look? It sounds like with the rough running at idle and slower speeds, you are rich at idle, and lean on the top end.
Elite HDF Member
Joined: Jun 2007
Posts: 4,867
Likes: 268
From: People's Republic of Boulder Colorado
Stay away from the DynoJet kits. A CV will run fine without dorking it up with one of those kits. Do a little reading and you'll see most "in the know" don't recommend them.
Yes temp and altitude will make a difference. The first thing I would suspect would be the 50 slow jet. That seems a tad too big for a mostly stock bike. Most are running a 46. I run a 46 in the summer and a 48 in the winter. When it's cold it runs leaner.
Did your dyno guy give you a readout showing you your AFR's from idle on up?
Yes temp and altitude will make a difference. The first thing I would suspect would be the 50 slow jet. That seems a tad too big for a mostly stock bike. Most are running a 46. I run a 46 in the summer and a 48 in the winter. When it's cold it runs leaner.
Did your dyno guy give you a readout showing you your AFR's from idle on up?
The one in my bike consists of only a different slide spring and jet. The slide & everything else on the carb & the rest of the bike is all OEM.
Outstanding HDF Member
Joined: Jan 2008
Posts: 3,328
Likes: 15
From: Pacific Northwest
Maybe I'm just lucky, but my '94 Dyna had a DynoJet kit in it when I got it and it runs great at all altitudes - 11,000+ ft. & temps - 40-100 degrees. Solid 60+ MPG every time anywhere.
The one in my bike consists of only a different slide spring and jet. The slide & everything else on the carb & the rest of the bike is all OEM.
The one in my bike consists of only a different slide spring and jet. The slide & everything else on the carb & the rest of the bike is all OEM.
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Elite HDF Member
Joined: Jun 2007
Posts: 4,867
Likes: 268
From: People's Republic of Boulder Colorado
Must be dumb luck for me too since I've used several DJ kits over the years (4 different personal bikes and a few buds' bikes as well) with great results. Guess I've "dorked up" quite a few bikes 'cause I'm not "in the know". They all got great mileage and improved performance with those kits.
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When I studied all this, it seemed that the sporty needle and bigger pilot were the best option, and leave the stock mains alone. I run a 48 and when it's cold out it acts like it wants a 50, but otherwise runs perfectly.
One thing to look for is intake leaks if you are needing a 50 in the heat, and overheating at low altitude.
In the fuel mileage thread I started, no one seems to be getting over 50mpg - 60 sounds very lean. I get 47 myself solo, and up to 42 when 2up.
One thing to look for is intake leaks if you are needing a 50 in the heat, and overheating at low altitude.
In the fuel mileage thread I started, no one seems to be getting over 50mpg - 60 sounds very lean. I get 47 myself solo, and up to 42 when 2up.
Extreme HDF Member
Joined: Nov 2006
Posts: 13,389
Likes: 26
From: Windham,Maine
Since we are reading everyones special carb choice.Mine has been since the 70's the S&S Super series.Have run them all,the bottom line is dailing them in.Discovered Dan Davinci modified S&S carbs and truly amazed at the difference in performance.Good Luck