1996 fatboy 13.7k miles
stock Kiehin carb
stock air cleaner
Jets: 185 main 48 pilot

this bike was originally in Wisconsin now at 5k feet of elevation
carburetor accelerator tower squirts towards the rear jug.
Found no air leaks.
need a little expert advice.

Front jug left, rear jug right

 

I'd check for an intake leak between the intake and the front head.
That said your running rich and need to dial back on the fuel going into your motor a bit.

 

I have a 45 jet to replace the 48. Should I do that too?

 

Yes, rear jug is way too rich, and front is "passable". The issue is the major difference in appearance with the front vs the rear. As TexasHill mentioned, the front manifold seal is probably leaking, making the front look leaner than the rear.

I would change out or at least check for leaks in manifold seals, then see how both plugs look before going to the 45. The 45 will probably be better at your new elevation. If you want to, you can try and turn the accelerator pump so it sprays more in the center but you really shouldn't notice as much of a difference as you see in your pics.

Whats with that crusty stuff on the base ring of the front jug plug? YD

 

Do one thing at a time,
You might need to re jet but I doubt it.

 

+1 ^

WAY too much anti-seize on those plugs! What pipes are you running and what plug number are those and how long have they been in? With a 48 low jet, about 2 turns out (+ or - 1/2 turn) if the mixture plug has been drilled out. If not, go back with the 45. Do you know how to read your timing using a (brand) new plug?

 

If your all ready running a severe rich plug adding fuel just doesn't seem a good direction. A 45 should be all you need for a stock engine. Ok lets throw the flag up on the rear cylinder and make sure it is sound, at 13k it is easy to assume the cylinder is ok but assuming can led to misdiagnoses, low compression will cause incomplete combustion in the cylinder. I'm going with a compression test before spinning out of control on changing things

 

I had anti seize all over my finger when I tried to take these pics.

I am checking for vacuum leaks by spraying carb cleaner on the seals while the engine is idling. I get no difference in the idle rate.

 

Just ragging on you I like automotive chemicals - anti-seize, thread locker of all strengths, etc. Anti-seize affects heat transfer so on plugs, a tiny little bit goes a long way.

Part of the fun of an older bike is tinkering with it. I don't know, but looks like those plugs have a number miles on them and one (or both) can soot up in a matter of minutes in these engines. I really doubt you have anything to worry about. Put in a couple new Champion RN12YC (they're cheap) and ride it a few days then check them again.

 

Running RN12YC gapped at .040”

not sure what those pipes are. They are not stock. The original owner had these pipes put on and he ran them without baffles. I had baffles put back in.

I did straiten out the accelerator so it squirts in the middle of the bore. Changed to a 45 jet and will be taking a ride in a few minutes. I don’t want to run this too much if it is lean. I don’t want to burn a hole in the piston.

Checking for vacuum has been a tad frustrating. I was told to use carb cleaner and spray onto the intake seals but I do not notice any change in the idle speed. Is there a better way? Setting the manifold intake is a real chore trying to get a ground down Allen wrench in there. I have reset it but feel I will have to do this again, and again if needed.

I am retired and living hand to mouth as it is. I really appreciate everybody’s input. I just don’t have the resources a mechanic would have.