Carb change?
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HDF Community Team
Joined: Mar 2005
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From: The 1980's
Carb change?
Got a 2002 Fat Boy carb. Bought it new, only owner. Approximately 36k miles. Last year while on vacation in Florida had some issues with it cutting out/stumbling for a half second or so intermittently at highway speeds.
After I got it home I left it at the dealer. Tank had been previously coated and was peeling badly according to them. Had been considering new paint so this was a good time to buy a brand new tank from J&P and do the repaint.
Bike was apart and not ridden for entire season last year. (I have a spare bike). Paint gets done, dealer puts bike together this winter. Fast forward to now. I'm in Fla. on vacation again. Same problem with the stumble.
My guess is that the dealer never took the carb apart or blew out the lines. I removed float bowl and it's clean. Main jet is clean. So the issue has to be elsewhere in the carb. I'm sure it's a fuel issue because pulling the enrichener clears it up.
Dealer is getting the bike back, along with an earful when I get home. I'd like some opinions on whether I should get the stock CV carb rebuilt and stick with it or try something different like an S&S, Mikuni, etc.
would cables or any other hardware need to be changed if I went this route?
The bike has had the heads reworked and gear drive cams. I'm not home so I don't have the specifics on that stuff.
After I got it home I left it at the dealer. Tank had been previously coated and was peeling badly according to them. Had been considering new paint so this was a good time to buy a brand new tank from J&P and do the repaint.
Bike was apart and not ridden for entire season last year. (I have a spare bike). Paint gets done, dealer puts bike together this winter. Fast forward to now. I'm in Fla. on vacation again. Same problem with the stumble.
My guess is that the dealer never took the carb apart or blew out the lines. I removed float bowl and it's clean. Main jet is clean. So the issue has to be elsewhere in the carb. I'm sure it's a fuel issue because pulling the enrichener clears it up.
Dealer is getting the bike back, along with an earful when I get home. I'd like some opinions on whether I should get the stock CV carb rebuilt and stick with it or try something different like an S&S, Mikuni, etc.
would cables or any other hardware need to be changed if I went this route?
The bike has had the heads reworked and gear drive cams. I'm not home so I don't have the specifics on that stuff.
Seasoned HDF Member
Joined: Mar 2010
Posts: 38,293
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From: Honah Lee
Just my opinion but the small idle circuit as you trottle up still comes into play but at highway speed still sounds like it's a tank,screen,sock issue. At 2002 and 36K, make sure all the other stuff it good. Plugs, airfilter, spark plug wires. Your problem is you are paying someone to fix a very elusive problem. And there are few probably who can take the time to get it right and make a living. If they cain't get the OEM right, what's the chance of them getting it reengineered for another carb? Just my opinion. You need to learn how to work on your antique if you are ever going to be happy with it. Or the money you are waisting spending on it would be better off on a new one those part changers know how to work on nowdays.
Outstanding HDF Member
Joined: Oct 2016
Posts: 2,530
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From: Wayne County, PA
I love my mikuni. Not a fan of s&s super e's. Flat and round slide mikunis have been on sportbikes, dirtbikes, snowmobiles, and everything in between for decades. Throttle response is phenomenal on my evo with a hsr42.
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HDF Community Team
Joined: Mar 2005
Posts: 1,863
Likes: 521
From: The 1980's
Just my opinion but the small idle circuit as you trottle up still comes into play but at highway speed still sounds like it's a tank,screen,sock issue. At 2002 and 36K, make sure all the other stuff it good. Plugs, airfilter, spark plug wires. Your problem is you are paying someone to fix a very elusive problem. And there are few probably who can take the time to get it right and make a living. If they cain't get the OEM right, what's the chance of them getting it reengineered for another carb? Just my opinion. You need to learn how to work on your antique if you are ever going to be happy with it. Or the money you are waisting spending on it would be better off on a new one those part changers know how to work on nowdays.
Tank shoul be good. It's brand new and was coated/sealed with Caswell when it was out for paint. One would hope that the sock/screen was cleaned or replaced after the previous problems and age of the bike, but who knows? Air filter was cleaned. They specifically mentioned that.
Rode a lot of snowmobiles with those from the 70's through the 90's. Very few problems.
Last edited by 2goldens; Apr 8, 2017 at 08:48 AM.
Seasoned HDF Member
Joined: May 2008
Posts: 21,023
Likes: 12,545
From: South Carolina
You don`t need to spend money on a new carb to fix a 5 dollar problem.
Pull the carb, disassemble and clean, especially the low speed circuit.
You may need to drill out and remove the plug that covers the idle mixture screw.
When removing the idle mixture screw, be careful you don`t lose the washer, the O ring or the spring, they are tiny...
Pull the carb, disassemble and clean, especially the low speed circuit.
You may need to drill out and remove the plug that covers the idle mixture screw.
When removing the idle mixture screw, be careful you don`t lose the washer, the O ring or the spring, they are tiny...
Outstanding HDF Member
Joined: Oct 2016
Posts: 2,530
Likes: 546
From: Wayne County, PA
Make sure you don't launch one of the springs in the accelerator pump across the room of the local bike shop. Ask me how I know hahaha. Then you will have to get a mikuni. Top 3 best bike upgrades on mine, the mikuni is up there. Hot starts are easier than cold ones too. I like to say you set it(not that difficult) and forget it.
Road Warrior
Joined: Jul 2012
Posts: 1,566
Likes: 55
From: Londonderry, NH
Got a 2002 Fat Boy carb. Bought it new, only owner. Approximately 36k miles. Last year while on vacation in Florida had some issues with it cutting out/stumbling for a half second or so intermittently at highway speeds.
After I got it home I left it at the dealer. Tank had been previously coated and was peeling badly according to them. Had been considering new paint so this was a good time to buy a brand new tank from J&P and do the repaint.
Bike was apart and not ridden for entire season last year. (I have a spare bike). Paint gets done, dealer puts bike together this winter. Fast forward to now. I'm in Fla. on vacation again. Same problem with the stumble.
My guess is that the dealer never took the carb apart or blew out the lines. I removed float bowl and it's clean. Main jet is clean. So the issue has to be elsewhere in the carb. I'm sure it's a fuel issue because pulling the enrichener clears it up.
Dealer is getting the bike back, along with an earful when I get home. I'd like some opinions on whether I should get the stock CV carb rebuilt and stick with it or try something different like an S&S, Mikuni, etc.
would cables or any other hardware need to be changed if I went this route?
The bike has had the heads reworked and gear drive cams. I'm not home so I don't have the specifics on that stuff.
After I got it home I left it at the dealer. Tank had been previously coated and was peeling badly according to them. Had been considering new paint so this was a good time to buy a brand new tank from J&P and do the repaint.
Bike was apart and not ridden for entire season last year. (I have a spare bike). Paint gets done, dealer puts bike together this winter. Fast forward to now. I'm in Fla. on vacation again. Same problem with the stumble.
My guess is that the dealer never took the carb apart or blew out the lines. I removed float bowl and it's clean. Main jet is clean. So the issue has to be elsewhere in the carb. I'm sure it's a fuel issue because pulling the enrichener clears it up.
Dealer is getting the bike back, along with an earful when I get home. I'd like some opinions on whether I should get the stock CV carb rebuilt and stick with it or try something different like an S&S, Mikuni, etc.
would cables or any other hardware need to be changed if I went this route?
The bike has had the heads reworked and gear drive cams. I'm not home so I don't have the specifics on that stuff.
If that checks out, go through the carb. It's most likely either jetted incorrectly, has a blocked jet, or there's a problem with the accelerator pump.
Look carefully at the accelerator pump and make sure there's a stream of gas into the venture when activated. They have been known to fail.
I'd also examine the slide diaphragm. Make sure its seated properly and there are no pinholes or tears.
All the above is cheap and simple if you can do if yourself...and it's a very simple carburetor to work on. If you aren't comfortable doing the work yourself, it may be costly to have someone go through it.
That carb should suit your requirements, and it should be a simple fix to get it running properly.
I assume you've also looked at the ignition system. Bad spark plugs, ignition coil, or wires are often misdiagnosed as a carburetor problem.
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HDF Community Team
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From: The 1980's
If it only stumbles at speed and recovers when you use the choke, then it's a lean condition. Verify that the fuel delivery system(fuel lines/petcock/screen) is functioning correctly.
If that checks out, go through the carb. It's most likely either jetted incorrectly, has a blocked jet, or there's a problem with the accelerator pump.
Look carefully at the accelerator pump and make sure there's a stream of gas into the venture when activated. They have been known to fail.
I'd also examine the slide diaphragm. Make sure its seated properly and there are no pinholes or tears.
All the above is cheap and simple if you can do if yourself...and it's a very simple carburetor to work on. If you aren't comfortable doing the work yourself, it may be costly to have someone go through it.
That carb should suit your requirements, and it should be a simple fix to get it running properly.
I assume you've also looked at the ignition system. Bad spark plugs, ignition coil, or wires are often misdiagnosed as a carburetor problem.
If that checks out, go through the carb. It's most likely either jetted incorrectly, has a blocked jet, or there's a problem with the accelerator pump.
Look carefully at the accelerator pump and make sure there's a stream of gas into the venture when activated. They have been known to fail.
I'd also examine the slide diaphragm. Make sure its seated properly and there are no pinholes or tears.
All the above is cheap and simple if you can do if yourself...and it's a very simple carburetor to work on. If you aren't comfortable doing the work yourself, it may be costly to have someone go through it.
That carb should suit your requirements, and it should be a simple fix to get it running properly.
I assume you've also looked at the ignition system. Bad spark plugs, ignition coil, or wires are often misdiagnosed as a carburetor problem.
The bike has run well forever, so it doesn't seem like poor jetting. But with the tank cream peeling issue that began the whole mess, could very well be an internal carb issue. Tank is brand new, but my experience with this outfit would not surprise me if petcock, screen etc. we're not cleaned properly.
New Scott wires and NGK iridium plugs were installed yesterday. No change.
On top of the carb issue, the bike had zero rear lights working when I got it back. Everything was in good working order before they removed the sheet metal. Funny that the bike passed a state inspection after they reassembled it but it suddenly had no working tail lights. A friend and I diagnosed that as reinstalling the load balancer and run/turn/brake module in the incorrect order.
He told my wife that he'd "make it right" by me when I return. We'll see how that goes. If it doesn't work out I'll buy a rebuild kit and learn stuff I never really wanted to know about a CV.
Last edited by 2goldens; Apr 9, 2017 at 10:59 AM.
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Seasoned HDF Member
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From: Honah Lee
Not sure how your carb 2002 controls or even has a control for spark retard with ping detection but my 2004 FI use the plug resistance. Make sure the aftermarket wires and plugs has the same spec as OEM. However, I doubt that is the problem.
Worked on a similar year Roadking someone had that he just poured the whole bottle of stablizer in there. The tank lining and pecock screen were all trash in the tank. My first attempt at fixing it did not work. After my first attempt, bike seemed to run fine one minute and the next, it would be pouring gas out the carb vent hose. Ended up cleaning carb again and replacing fuel line just to make sure.
Worked on a similar year Roadking someone had that he just poured the whole bottle of stablizer in there. The tank lining and pecock screen were all trash in the tank. My first attempt at fixing it did not work. After my first attempt, bike seemed to run fine one minute and the next, it would be pouring gas out the carb vent hose. Ended up cleaning carb again and replacing fuel line just to make sure.
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