What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Anybody tinker on Harleys? Could use some help.

shima

shima

1/2 ton status
 Premium
GMOTM Winner
Joined
Jul 19, 2016
Posts
1,307
Reaction score
1,494
Location
Denver
Hey guys, my 1998 XL1200S is running rich and I can't figure out why...

Super Short Backstory
I let it sit for a few years. When I started it again for the first time it revved to the moon. It would only stay running with choke pulled. I replaced the intake seal where the carb sits. After that I cleaned the carb and the tank which led to a rabbit hole of doing all sorts of things. Now it's running really rich and I'm running out of ideas on how to fix it.

HERE is a link to a short video that shows the bike running and lists everything that I've done so far.

Listed explicitly:
  • Rinsed out tank (2x)
  • Cleaned carb up and down (2x)
  • Verified float level
  • Verified jet sizes (45 / 185)
  • Tested and replaced petcock
  • Checked the slide diaphragm
  • Adjusted the mixture screw (1.5 turns from seated)
If anybody has any ideas, throw 'em at me. Someone on reddit suggested an Italian tune-up with some Seafoam and I thought that wasn't a bad idea. Other than that I am clueless.
 
I am by know means knowledgeable on any motorcycle but it sounds like the float might be stuck. When you said you cleaned it was it just hosing it down externally with carb cleaner or did you actually take it apart and clean all the crap our modern fuel leaves behind?

I don’t know on those carbs if you have to take them apart to get to the jets or what so you may have had it apart. But it’s pretty common for any carburetor that has sat with fuel in it to stick the float, needle/seat or both. That’s going to make it run super rich regardless of any adjustments.

That’s my uneducated guess there.
 
Likely have an intake leak. The "choke" is technically an enrichener. As in, it adds fuel, rather than cutting off/choking the air flow.

So if it runs with the choke on, it means that it's needing more fuel to deal with excessive air. Likely it's the intake seals where the intake meets the heads. They are made of rubber and typically dry out and harden, while also having the aluminum of the head corrode.

When replacing the intake seals, be prepared for the 1/4" Allen screws to round out. They make a special wrench that makes it easier to get the left bolts, but not always easy. Also helps to have a long ball Allen to reach the right ride bolts. I like to have replacement bolts on hand before I start, just in case. I also usually swap out the left side 2 bolts for standard 1/2" head hex bolts.

When replacing the intake seals, I recommend getting the intake assembled loosely to the heads, then install the carb an aircleaner backing plate. This will hold the intake in the right position. Then tighten down the intake bolts.

It sounds like you've already replaced the seal ring between the carb and intake manifold. If not, I would. If you have, make sure you have it on correctly. I've seen the lip catch and fold, or get cut, before.

Also need to make sure it doesn't have and vacuum port open. Some models had a port with a little rubber cap that dryrots or gets knocked off.

Intake seal PN: 26995-86B
Qty: 2

Intake bolt PN: 3275
Qty: 4

Carb to intake seal ring PN: 27002-89
Qty: 1

Intake wrench:
 
1777032819030.jpeg
I've got the ratcheting style. There's several different brands. . There's also a standard Allen wrench type.

1777032865779.jpeg
 
Thanks for responding guys!

ZooMad75 said:
I don’t know on those carbs if you have to take them apart to get to the jets or what so you may have had it apart.
Click to expand...

Yeah, I took the whole thing apart and blasted the passages with carb cleaner. I found a neat video on checking the float level here and verified it looked good.

eric67camino said:
It sounds like you've already replaced the seal ring between the carb and intake manifold.
Click to expand...

Yep, I replaced that first thing. Right now, the bike will run without choke... but when I rev it I can see clouds of black smoke being shot out the exhaust. If it give it more than a blip of throttle it dies on me.

Other than using Seafoam to make sure I got all of the crud out of the carb, I am definitely interested in revisiting the choke/enrichener. Maybe it is stuck open even when I think it is closed.
 
Definitely wouldn't hurt to check the choke again. The brass plunger part (Harley calls it the starter valve PN: 27583-88) has a tendency to get scored or burnt, and would recommend replacement.

I would want still lean towards replacement of the intake seals. Number 3 in the picture. Given the age, the symptoms, and having been parked a while, that would be my inclination.

1777050015355.png
 
eric67camino said:
I would want still lean towards replacement of the intake seals. Number 3 in the picture.
Click to expand...

Man I really appreciate your responses. I will say that when replacing the seal ring (#6), I did spray carb cleaner near the heads with the bike running. Wanted to try the old "listen for the RPMs to change" trick. I couldn't hear any change in RPM... so I am hoping those cylinder head seals are still good.
 
shima said:
Man I really appreciate your responses. I will say that when replacing the seal ring (#6), I did spray carb cleaner near the heads with the bike running. Wanted to try the old "listen for the RPMs to change" trick. I couldn't hear any change in RPM... so I am hoping those cylinder head seals are still good.
Click to expand...
I do the same. Have a custom tool that uses a small propane bottle, like for a camp stove or lantern. With a push button valve on top. That runs through a rubber hose to a piece of copper tubing. The copper tubing has the end almost flattened. This allows me to put the tip right at the seal where I suspect there's a leak. Then, with the bike running, I can press the valve for just a second or two and see if the idle changes. Switching from place to place.

Using a traditional spray can puts it all over. So it's harder to locate. I've also have it suck into the aircleaner that way, thus nullifying the test in that instance. You can try to localize with a spray straw, but it's still harder to control.
 
Of course, it could still be something else. A plugged slow jet or idle mix passage can cut off enough fuel that the choke helps. If you cleaned the carb and verified all the passages are clear and the jets are good, I would lean towards the seals.

Worst case, the two intake seals, 4 bolts, starter valve, and a new slow jet are only like 36 bucks.
 
If the engine does not flood when not running and the fuel valve open, it is not the float.

What you are describing is a rich condition. If the RPM's run up, it is not starving for air. The black smoke is obviously too much fuel for thr spark and compression to fully use. Are the jets seated completely? Did you miss one when installing. Ask me how I know that one.

Check the plug for good, blue spark. But I think it is in the carb.
 
I would double check that you can see light through the jets. Had a moto sit for a few years, cleaned up the carb and hardly run. My buddy at the scooter shop found jets mostly plugged. Ran all the parts through an ultrasonic cleaner. Ran flawless after.
 
So I thought for sure I had seen somewhere that my jet sizes (45 / 185) were stock.

Double-checking the manual tonight:

IMG_0241.jpeg

Looks like I’m supposed to have a larger main jet (195) and a smaller slow jet (42).

I guess getting the correct jet sizes would be a good start… lol
 
Are your air cleaner and exhaust stock?

If not, the 45 jet may be to add fuel to match a high flow air cleaner, or free-er flowing exhaust.
 
You can also look to see if the idle mix screw cap has been removed. It's plugged from the factory so that the idle mix can't be adjusted. Part of rejetting the carb for air cleaner, exhaust, etc., is to remove the plug and readjusting the screw.
 
You must log in or register to reply here.

Latest Posts

Top Bottom