It has been running well

[2steve]

Discovered some more tuning to do. The 2.5 slides with UFO's in the bottom of them were pulling more fuel. So that forced dropping the needles 1/2 step. Then too much congestion at throttle just starting to open. Opened the air jets to 3 turns out and still too much. Next step is one size down on the pilots. HOWEVER, I saw the wiring collection from the generator/ignition side had migrated back toward the chain  Doesn't look like it's touching the chain yet. No prob, I'll dig it upward and zip tie it safely before things get bad.

They already were. One white gen wire completely sawed apart. How was it running with no problem whatsoever with old style headlight bulb and a dinky alarm battery?
How can any wire in the RD400 wiring harness be open and there's no problem?

[mnein]

Good one to figure out Steve. It looks like you're giving the wiring harness the finger in that pic.

[1976RD400C]

It was still charging with the broken wire, just at a reduced rate. Probably enough for the ignition and headlight. When I installed the UFOs my pilot had to go from 50 to 25.

[2steve]

You saved me some time, 76RD400C.
Instead of moving from 32.5's down to 30's, I skipped down to 27.5. Ran better today at 2 turns out, but still a little rich.
Going to try it at 3 turns out, then likely go to 25's.

It was nice that the front wheel lifted with purpose right along with the torque curve on stock gearing, then shifting quickly to 2nd, caused it to lift a little on the bounce. Lights were a little brighter with the repaired wire.

[m in sc]

sweet. glad you found it.   

[2steve]

Having read the UFO datasheet and anticipating moving down to 25 pilots, I believe there may be an impact on every circuit above the pilot. Moving from 32.5 to 25 pilots might make leanness anywhere above - looks like. Maybe even the main jet.

Maybe someone has experienced this?

Hoping not to learn the hard way.

[Brad-Man]

Pilot jet affects up to ~1/2 throttle...

[2steve]

So, that's a little pilot/air screw and a little main adding into the needle and needle jet, it seems.
I'll carefully monitor.

Glad I got fresh carb slide screws from Economy Cycle. Those and the front tank rubber mounts just came in and were Genuine OEM Yamaha