My new/old FXRS (1990 model) is running very nicely. Did a three-hole fluid change over the weekend, adjusted the clutch, changed the plugs. It ran well before, but its even better now (I think the RedLine tranny fluid made a real difference).

Anyway, my only gripe with it is that it has a distinct hesitation/surge when its cold. My morning ride includes about a mile of straight, flat road just past my house. Holding the throttle constant, you can feel a steady series of brief (but very minor) hesitations. Once it warms up fully, it goes away.

As far as I know, everything on the bike is box stock (pipes, ignition, air cleaner, mechanicals, etc). I haven't pulled the carb to see if the mixture screw been drilled, but I'm guessing it hasn't.

Its my intent to keep this bike completely stock, but I'm also thinking that the factory carb setup was made overly lean for EPA purposes.

So my questions are:

1) Does all of that make sense, or am I smoking rope?

2) Assuming the carb is still on its factory setup, would it make sense to drill out the mixture screw and back it off a bit?

3) Is there any reason/benefit to rejetting if I have currently have the factory jets?

4) Is this possibly caused by something else (I'm thinking perhaps perished seals between the carb and the manifold)?

I'll probably get a chance to pull the carb this weekend and see what's up. Can anyone tell me which jets it came with from the factory?

 

Definitely gain access to the mixture screw if it's plugged, 1/4-1/2 turn open might be all you need, a point or two bigger pilot jet may work better, especially with todays 10%+ ethanol fuel.
Never hurts to verify there's no intake leak before jetting changes so you don't end up trying to compensate for one.

 

2). Yes!

4). Probably not.

It sounds as if you have only a slight problem, if a problem at all! After all if the engine is fine once warmed up, then ride on.

 

You're gong to get several more responses, but everything you asked is well answered by the above two posts. The only thing I may add is that, since your bike is 24 years old, it wouldn't be too bad an idea to pull the carb off and give it a thorough cleaning and inspection. I would replace the intake manifold seals at that point and maybe the accelerator pump diaphragm. You should be good to go at that point.
DO NOT drill the slide or add a Dynojet kit. More trouble than they are worth.

 

That's a good idea right there. And I'm thinking I may as well refresh the seals and gaskets while I have it apart.

Which brings up another question: Is there a particular gasket kit that is preferred?

 

The HD stuff will do just fine.

 

Th H-D overhaul kit comes with gaskets, O rings etc.

 

If you are getting into the carb, take the extra time to change the carb to manifold donut gasket. It's cheap from the MoCo and they are likely to leak. My bike has the stock carb and intake and I have been through a couple of these in the last ten years. it's a good excuse to clean the carb while you have it off.