CV carb issue
Thread Starter
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Intermediate
Joined: May 2011
Posts: 47
Likes: 0
From: Philly Pa
CV carb issue
This is on my 99 Evo Softail. It's got a Ness Big Sucker and Python Stagger Duals. Previously it had a Hypercharger and V&H Short Shots. Same issue.
When you're riding and you're on a long decel with the trottle closed, occasionally when you give it some gas it'll pop or fart through the carb before accelerating normally. It will only pop once and it doesn't do it all the time. It seems to do it more in cold weather than hot weather. And yes, the bike is up to full operating temp when it does this. That seems to be 175 or so in cold weather (50* ambient) up to low 200's when it's really warm out.
I have absolutely no idea what's been done inside the carb by the PO. Bike runs great overall, plugs have a light tan color to them and I get 38-39mpg pretty consistently.
To me I feel it's in the pilot circuit and while the main jet was probably changed, I doubt they changed the slow jet. I keep reading so many different "Fixes" for the CV carbs that my head is spinning. The bike runs great except for that one thing.
Should I dig out the idle mixture plug and make a small adjustment there? Or should I get a new slow jet and go up one size?
Also, I see people talk about using a sportster needle? Is that something I should look into? I don't want to kill the MPG. I've got plenty of gas hogs, I don't need another one, especially with $4 gas. The fart is getting annoying though...
Thanks
When you're riding and you're on a long decel with the trottle closed, occasionally when you give it some gas it'll pop or fart through the carb before accelerating normally. It will only pop once and it doesn't do it all the time. It seems to do it more in cold weather than hot weather. And yes, the bike is up to full operating temp when it does this. That seems to be 175 or so in cold weather (50* ambient) up to low 200's when it's really warm out.
I have absolutely no idea what's been done inside the carb by the PO. Bike runs great overall, plugs have a light tan color to them and I get 38-39mpg pretty consistently.
To me I feel it's in the pilot circuit and while the main jet was probably changed, I doubt they changed the slow jet. I keep reading so many different "Fixes" for the CV carbs that my head is spinning. The bike runs great except for that one thing.
Should I dig out the idle mixture plug and make a small adjustment there? Or should I get a new slow jet and go up one size?
Also, I see people talk about using a sportster needle? Is that something I should look into? I don't want to kill the MPG. I've got plenty of gas hogs, I don't need another one, especially with $4 gas. The fart is getting annoying though...
Thanks
Road Warrior
Joined: Oct 2009
Posts: 1,251
Likes: 1
Do yourself a favor and see what you currently have as far as jets in the carb, sounds a bit lean on the pilot, secondly, if you haven't removed the aluminum plug for the idle mixture screw, do so, Harley has these things set really lean from the factory sometimes, good luck, chad
Ultimate HDF Member
Joined: Jun 2007
Posts: 9,193
Likes: 494
From: Richmond, VA
As mentioned, your running a tad lean on the slow jet. Its probably the most common and universal problem with carbed Evo's. Yes, pull the float bowl and remove the pilot jet. See what it is. Most likeley you will need to go up a size. Also see where your at with the mixture screw. Has the plug been removed? Can you get to the screw? If so, screw it all the way in and gently seat it. Back it out 2 1/2 turns. Ride. If its still farting, go out to 3. If it gets considerably better, your pilot is too small.
Thread Starter
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Intermediate
Joined: May 2011
Posts: 47
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From: Philly Pa
Can you pull the bowl without pulling the carb? I want to order a CV Performance kit and some other goodies but I'd like to know what main/pilot jet I have first. Once all the parts are here I'll yank the carb and do all the upgrades.
Should I change the emulsion tube or slide spring? The bike is stage 1 right now but at some point I plan on adding cams. Nothing outrageous but maybe an EV-27 or similar.
Should I change the emulsion tube or slide spring? The bike is stage 1 right now but at some point I plan on adding cams. Nothing outrageous but maybe an EV-27 or similar.
Seasoned HDF Member
Joined: May 2005
Posts: 10,232
Likes: 9,325
From: Georgia
Mine will do the same thing once in a blue moon but I don't think it's gonna get any better buy changing things. It starts easy plugs couldn't be any better color.I run pretty much the same set up as you have.Your mileage is way off from most Evo's I know of. I get 50 all the time unless I have long runs on the interstate at 85 +.It will still only go down to 45 or so.
How's it coming along John? Maybe just before the Memorial day holiday we're going to take a cruise over your way. I'll be in touch. G.
How's it coming along John? Maybe just before the Memorial day holiday we're going to take a cruise over your way. I'll be in touch. G.
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Elite HDF Member
Joined: Sep 2007
Posts: 4,468
Likes: 12
From: Bluffton, South Carolina
Gordo, give me a call so that we don't make any other plans.
John
John
Mine will do the same thing once in a blue moon but I don't think it's gonna get any better buy changing things. It starts easy plugs couldn't be any better color.I run pretty much the same set up as you have.Your mileage is way off from most Evo's I know of. I get 50 all the time unless I have long runs on the interstate at 85 +.It will still only go down to 45 or so.
How's it coming along John? Maybe just before the Memorial day holiday we're going to take a cruise over your way. I'll be in touch. G.
How's it coming along John? Maybe just before the Memorial day holiday we're going to take a cruise over your way. I'll be in touch. G.
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Joe Kucinski
Club Member
Joined: Apr 2011
Posts: 5,817
Likes: 7,850
From: SE Louisiana
Check for intake leaks first, before you go richening it up, the mileage is kinda low already, unless your always on it hard, then it's not far off.
My fully loaded bagger with two up gets 40 on the interstate at 75.
The stock slide and spring will work best unless there's some heavy mods to the engine.
My fully loaded bagger with two up gets 40 on the interstate at 75.
The stock slide and spring will work best unless there's some heavy mods to the engine.
Road Master
Joined: Apr 2009
Posts: 1,123
Likes: 43
From: NJ
Nice bike, I had a 99, same color!!
Do you get popping on deceleration?
Forget the kit, you are only @ stage one and don't need it. 9 out of 10 times if the plug is still in the mixture screw then the carb has not been messed with. You can take the bowl off while the carb is on the bike but to get the plug out you should remove the carb. Your MPG is below average so unless you are playing goosey-loosey with the throttle, you don't want to add too much fuel. All that being said, you are describing a common lean condition, here is what I would do in order:
Check for intake leaks.
Verify that the accelerator pump gives a good shot right down the middle.
Take carb off, clean it, remove mixture plug and discover what jets you have. Replace the bowl screws with allens-makes it easier to take it off when the carb is on the bike.
Reassemble-(fix intake if needed)-
Back the idle mixture out, often 2.5 turns from gently seated, 3 max.
If still an issue up the low speed jet one size.
This site has alot of good info, not just the page in the link...look around..
http://www.nightrider.com/biketech/hd_cv_mods.htm
Doug
Do you get popping on deceleration?
Forget the kit, you are only @ stage one and don't need it. 9 out of 10 times if the plug is still in the mixture screw then the carb has not been messed with. You can take the bowl off while the carb is on the bike but to get the plug out you should remove the carb. Your MPG is below average so unless you are playing goosey-loosey with the throttle, you don't want to add too much fuel. All that being said, you are describing a common lean condition, here is what I would do in order:
Check for intake leaks.
Verify that the accelerator pump gives a good shot right down the middle.
Take carb off, clean it, remove mixture plug and discover what jets you have. Replace the bowl screws with allens-makes it easier to take it off when the carb is on the bike.
Reassemble-(fix intake if needed)-
Back the idle mixture out, often 2.5 turns from gently seated, 3 max.
If still an issue up the low speed jet one size.
This site has alot of good info, not just the page in the link...look around..
http://www.nightrider.com/biketech/hd_cv_mods.htm
Doug