346xp 372xp tuned. Tachometer Warning.

[rngrchad]

I tuned up my new 346xp, and the 372xp tonight. Tach: SenDec MaxTach.
The 346xp I turned from 12,800rpms to just a hair under 14,000.
The 372xp I turned from 13,480 to 13,520.

I tuned both saws initially on the bed of my truck, then placed them both in ASH rounds to see the rpm difference while running through wood. Both saws were at least 2 or 3 thousand rpms less while "WOT" in the cut.

Spark Plugs
346xp: plug looked nice light tan or light brown. Perfect.
372xp: plug was rather white everywhere except behind the electrode where it was black. I'm scratching my head on this one....Dunno why the 346xp plug looked so much better than the 372. By the plug reading, I would think my 372 is running lean, but that sure isn't what the tach is showing. I bet I'll just have to get the 372 out for a few hours of real-world cutting conditions then check the plug.

I now totally understand why it is important to have a high-refresh rate on the Tachometer. I felt the Sendec MaxTach I was using was way to slow on responding to the the saw's WOT rev's. I'm new at tuning saws with Tachs, so it was really difficult for me to hold WOT for more than 3 or 4 seconds, but that is what it took or the tach would not reach an accurate rpm reading....too slow for my liking. The whole time I felt that there is no way that tuning a saw can be good for it. Too much throttle for too long of periods, or maybe I'm just paranoid.
-Chad
Pics added...but not useful becuase I have no idea how to get a clean looking cloesup with my brother's camera.
372 plug:

Tach:

 

[Longwood]

If your 372xp is fairly new it could have a rev limit coil. Pull the starter cover, if the coil is blue its a rev limit coil (see pic).A black coil is a not rev limit coil. If it is rev limit you have to be sure your not leaning the saw out and hitting the rev limiter thinking its 4 cycling. This can burn up a rev limit saw.

Here is how I adjust the High (H) screw my rev limit coil 372xp: With the tach working I hold the saw wide open throttle. With the (H) screw set rich I lean it out watching the rpms climb til the rev limit coil starts cutting out, which is about 13600 rpms on my saw. I then turn the screw(H) rich til the rpms come down to 13400 to 13500rpms. Finished with (H) screw.

If your 346 is a New Edition then it has a rev limit coil also which cuts out at about 14100rpms.

If a saw doesn't have a rev limit coil then I adjust it the highest rpm the saw will turn on the tach, then richen it to bring the rpm's down 200 or 300 hundred and I'm done. Don't be afraid to hold it wide open long enough for adjusting, you gota do it.

hope this helps.