Rock Flute: Tuning Session 2, in the rain.

I spent some time going over a few things on the bike prior to continuing with the carb tune. Tune the drive, tune the clutch etc. etc.  Tunessss mannn.  All positive waves.

 

I installed a 17 tooth front sprocket and a longer chain. Originally 15/48 3.2:1 final drive, now 17/48 2.82:1 final drive. 3.2 is loads of fun but not realistic for anything other than stupid fast bar hopping and light racing. 2.82 is within the range of stock but still toward the upper range to take advantage of the engine mods. The cam kicks hard at 5000 rpm and above. With the new final drive, a shift to 4th at 65 mph puts the bike right under this 5000 rpm threshold and a shift to 3rd ignites the rockets.

I also adjusted the clutch and put on a new cable. John "jleather" spun up a cute brass barrel adapter to replace the one I lost when my cable broke. Unfortunately after a lot of adjusting, I have to settle with a neutral that is very hard to capture. The clutch lever does not have enough throw to allow a clean shift to neutral and full compression of the clutch plates. Ohh well. Later I will find another clutch lever with a longer throw.

So finally to the CARB tuning. Like I said before, I'd resume with the 115 mains, 15 pilots, air screws at 1.5 turns, and the needles now all the way down. Well... its darn near perfect. There's an occasional tiny stumble with a slight rotation of the throttle off of idle. Its right at the bottom of the throttle cruising range for low speeds. The plugs are gorgeous but I can still feel the hesitation. The rest of the throttle range feels spot on and provides a slightly rich color to the plug base ring. Below is a picture of the plug chop cruising just above the stumble. The remainder of the chops at varying throttle all look similar this. Always work from the bottom up. Otherwise your lower throttle ranges can screw up your readings.

I'm going to try and tweak the stumble out with the air screws, but it's certainly something I can live with for now.  The strap looks a tiny bit hot so I may benefit from a spark plug with more heat capacity.  I'm running a .026" gap and might close it up a bit to see if I can get a more complete burn.  The balance between the increased compression and the higher spark voltage should balance out a bit to where a .026" gap is nearly ideal.... Maybe?  

The final steps are to replace the rocker shafts and run a tool over every nut and bolt. HOME STRETCH!!!