First off, a question for racked FCR 41 owners with velocity stacks or pods and stock bore + compression with altitude below 7,000 feet / 2133 meters
What size is the pilot (slow jet) and how many turns out from bottom is the slow air screw and fuel mixture screws?
Onto my issue:
Stock motor with Termigs.
155 main jet
EMT needle, third clip from top
60, 65, 68 pilot
200 main air jet
Blue velocity stacks
I have a recently rebuilt set of racked 41s that function very well on my M900 with W heads. But on my SuperSport's V heads with of course different sized jets and settings I am not able to dial in the idle-to-quarter throttle. I recently did a valve adjustment, compression test, ohm'd out the pickups (a little low at 102.3 or something per pickup) and the CCW coils, replaced the fuel filter, tested the fuel pump for 3.5 PSI, and replaced the fuel with fresh 91. For the record I am testing idle after 10 minutes of hard riding.
Initially the revs would hang sometimes up to 1-2k RPM above idle for 4-5 seconds with a 60 pilot. The motor would also heat up very quickly from being dead cold. In my eyes these two symptoms occurring together pointed toward a lean condition. Even after screwing out the fuel mixture screws until they nearly fell out the revs would still hang. I then installed brand new, larger pilots.
However, 65 was still hanging and so are 68 pilots. have only marginally remedied the hanging or perhaps it didn't even help at all...my head is messed up from inhaling fumes
. I have been tinkering with all kinds of combinations of the slow air screw and fuel mixture screws with the 65 and 68 but it still hangs. It won't hang much if I almost completely screw in the slow air screws, but then it will barely idle and eventually shut off.
I suppose I could increase the idle speed to maintain proper ideal RPM but I would have it screwed in completely and that seems like a band-aid fix.
To make matters more confusing to me, the sparks plugs are sooty, and I must occasionally burn the carbon off them before using them again. How can they be sooty, which is a symptom of being too rich, if hanging is a symptom of a lean condition? It doesn't make sense to me that the rich condition is coming from the needle position or the main jet, but this wouldn't have been the first time I'm wrong.
I'm waiting for 62 pilots. It's the only size I skipped.
Files attached for anyone who needs them.