97 Low Rider carb a little over 24,000 on the odometer.
Bike just recently started running really rough until well warmed up. Once its warmed up it runs like a top. Any suggestions?

 

I would pull the carby off, replace the carb to manifold rubber, re-set the float level, spray carby cleaner through all the passages and then check its got a 45 or 48 idle jet in.

That should fix it.

 

What kind of carb are you running?

 

Sounds like it's due for a carb cleaning. Pull it off, tear it apart, clean it up. As posted, set the float level, re-install, adjust the idle mixture (you have removed the EPA cap, right?), set the idle speed, and ride.

 

If you are going to tear it down may as well replace intake manifold rubber seals , between intake and cyl head.

 

About the only thing I've ever done on a carb is set the idle speed and replaced air filters. What's the EPA cap? It's the stock carb Keihin I think.

 

EPA cap covers the idle adjustment screw and it sits at the 6 o'clock position under the carby throat.

If you are not very mechanically minded I would avoid the head to manifold seals at this point as they are bit of a mission if you don't fully understand the job.

 

As Spanners39 replied, it's what 'prevents' the home gamer from enrichening the idle circuit. The MoCo, in the need to meet EPA regs, set the mixture lean. They then pressed a sheet metal 'cap' into the opening, covering up the jet. Removal allows access to adjust the jet. Adjusting it a bit richer, eliminates a number of cold running problems. At least that's been the case with my 93.

If you don't have the factory service manual, I would highly suggest you get one. There is a very good section on the carb, which explains how it works, and how to R&R it.

 

Removing that EPA cap involves gently drilling a hole through it and winkling it out with a small screw-driver. It is quite thin and doesn't need a hammer-drill, so take care! Underneath it is a brass slotted adjusting screw.

 

Just ride with the choke on until it warms up....not fully...about half way.....

then after a mile just reach down and close the choke.

That is if you cant wait to warm it up.

Murph