Long rambling post
I took the P11 for a ride Saturday without changing any settings on the FCR carburetors. With the engine warmed up and a load on the motor, it was not pretty. Rich would be an understatement on my Norton 750 engine. My engine is not fresh, so I wasn't expecting my plugs to look that great, but they looked like they had been sprayed with black velvet matte paint everywhere. The motor misfired here and there with a load on it. I can see why people think it is over carburetion.
So... I took the fastest route to making it run a little better, and I consulted google. Google brought me back here to Brian's FCR settings thread. I made the adjustments Brian used except for the main jet change. The difference in idle quality after making the slow speed adjustments was significant on a warmed up engine. I also moved the clip on the needle to the second grove from the top. I was going to move the needle clip after looking at the plugs anyway, but good to see that it worked in Brian's example. Idle is good, no load throttle response is great, but deceiving in the garage. Unfortunately, it's raining, and I don't ride in the rain, so have not had a chance to put a real world load on the motor to see how much difference the new settings make riding the bike. My optimistic fantasy of being able to use the out of box settings didn't last long. Not surprising.
Brian's settings information is listed below for anyone that hasn't already seen it. The settings should be good for a mild 750.
Slow Air Screw 2 turns out (This adjustment is made with the left hand screw at the air filter side of the carburetors with the air filter adapters removed.)
Slow Idle Mixture Screw 5/8-3/4 turn out (This adjustment is made at the intake manifold side of the carburetor from the bottom in front of the float bowls.)
Needle Clip Position 2nd clip from the top (Leaner setting than the as shipped 5th position from the top.)
Main Jet 145 (Optional before mounting, because it is easy to change later if you have room under the carburetors after they are mounted. Smart money would be to change mains before mounting. Order the main jets at the same time as the Sudco carburetor kit.)
After the test ride I also took additional material off the intake manifolds around the O.D. so I could move the connector boots closer to the head, I shortened the boots to 1 1/16". I could explain why, but it's too much babbling.
It's a lot of fiddling to get the Commando spigot intakes to work on an motor mounted with the cylinders in the vertical position, and it's not necessary now that I've done it, and see what the actual clearances are like. Short straight spigot manifolds would work with the FCRs. I'm not sure about getting the CRS carburetors to fit with straight spigot manifolds, because I have not done it.
It's not hard to cold start with the modified Commando intakes I hacked up, but requires a goofy procedure because the manifolds are not downdraft enough. What seems to work best is blip the throttle 3/4 to WOT about 5 times to squirt the accelerator pump, then with the key Off open the throttle all the way and kick the motor over 3 times, then turn the key On, and give it all you got with a little bit of throttle. I don't worry that much about washing down the cylinders on my Atlas setup, because the intake manifolds are very close to level before entering the head. Fuel from the accelerator pump doesn't flow right into the head easily without a lot of vacuum (motor running). When stone cold it doesn't want to get there at all just kicking it over, if I don't perform the goofy start up ritual. If I installed the straight intakes that put the carburetors at an increased downdraft angle, I would more than likely change the cold startup procedure.
My rationalization for not using a set of straight spigot intake manifolds in the first place is I did not think I could make the CRS carburetors I originally planned to use fit under the backbone of the frame. I figured the modified Commando spigot intake manifolds would provide more clearance. I then changed my mind and got the FCRs because they are not as tall above the intake as the CRS carburetors, and I knew I could make the FCRs fit. Now with the FCRs installed, it looks like I could make straight manifolds work with the FCRs. I could also install CRS carburetors on the Commando intake manifolds I just finished and the carburetors would be mounted at a proper angle for the CRS design, and the standard push pull cable setup would fit under the P11 tank.
