Rock Flute: Tuning Session 1

I've done a little work on the VM29 smoothbores since the engine rebuild. I bench synced the carbs to a random .116" because I don't have vacuum ports to sync them on the bike. First few runs its been running rich on 120 mains and 20 pilots. Tuning from the bottom up, I swapped jets to 115 mains and 17.5 pilots, which is the spec for a stock cb with vm29s. The bottom end was still incredibly rich but a lot better with the air screws out over 2.5 turns.

I dropped the pilots to 15s and kept the mains at 115. Idle looked good with 1.5 turns on the air screw but off idle was rich enough to cause a stumble. Plugs showed a lot of soot. Not wanting to mess with the pilots anymore, my suspect now is the needle and main. WOT pulls well without hesitation which indicates the main is close. To alleviate the stumble in the transition from idle to 1/8 throttle I dropped the needle down. The stumble was a lot less noticeable but still their.

I went for a ride to pick up a starter switch for johns bike and was going to drop the needle to its lowest position when I got back. Unfortunately I didn't make it home under my own power due to this little gem:

Jeff Yarrington and the Scooby Van to the rescue!  My million year old, burnt, dry clutch cable finally gave up the ghost. I couldn't find a picture of Jeff's sweet van but I did find a picture of him sleeping in it. Thanks Jeff!  He got me back to John's place where I dropped the tuning for a while and resumed wiring John's black chopper.  So many things to do.

 

My fruitless quest for a starter switch was kindly remedied by Jeff. When he picked up my bike he brought two momentary switches. What a friend. Thanks AGAIN!

Ok sorry.  Back to the tuning.  With a broken cable, I was down for the night.  My next step will be to drop the needles all the way down and then refine the a/f ratio based on some plug chops. Hopefully I'm good with the 115 mains because I feel like 112.5 or 110s on a hopped up engine is a bit absurd.  Just one more week before we leave for the Roost.  TIME IS RUNNING OUT!!!