The first run of the MS460, (The OEM top-end) and getting the carb halfway adjusted. The procedure is the same for many, many saws and only the numbers change. No tach? No worries.... Listen to how the engine responds to the adjustments...
It's a repeat for most around here but it's one of my most watched vids and it will do us good to have it linked to the forum.
This video definitely needed a link here. That was the single most helpful video I've used during my plunge into the depths of CAD. Very clear, and easy to follow. Thanks!
good repost. also the text you have written out helpa too for those who know what thier trying to hear but just need the orser to tune and adjust in.
some saws are easier to hear than otjers. the husky 372 is a well dedined 4 stroke. the stihl 390 is not as pronounced, so i was like u when i first messed with it.
The more free-flowing the muffler is, the easier it is to hear the four-stroking. Gut those cans boys!
I just watched this video 3 times on YT and then searched up the forum. I will do this for the MS460 I just rebuilt! Thank you so much for making this video MasterMech. These are my notes I wrote down: 1. 1 turn out on L and H 2. Adjust for 3300 on IDLE screw 3. Adjust L screw for max rpm 4. If max rpm goes over 3700 readjust IDLE 5. Turn IDLE screw down to 3300 6. Check throttle response and verify/adjust RPM 7. Richen IDLE to get to 2500 rpm 8. Check throttle response and verify/adjust RPM of idle and WOT 9. Listen to WOT. If too lean richen 10. Open H screw until saw stumbles 11. Then bring back to FULL LEAN BRIEFLY 12. Then richen H until saw 4-strokes 13. Check throttle response and verify/adjust RPM of idle and WOT
Just a note of my own: That saw in the video ended up a tad rich afterwards due to it having a rather free-flowing muffler compared to the standard US muffler. Tach readings are great, but engine behavior and your ears are the boss.
Wouldn't a free(er) flowing muffler cause it to be a little lean? And the sound of a dual port sure is different that the stock muffler!
Not if you are forcing it back down to an RPM target with fuel. If I had tuned by ear, I probably would have ended up around or just over 14k. Which I did, just not on camera.
So isn't the hard limit 13,500 because any higher and the piston starts getting too hot and the potential for scoring increases drastically? Are you saying it's better to tune by ear? Or is it better to tune to an rpm limit using a tach? Or are you saying it's better to tune by ear when using a free flowing exhaust because you're lowering the temps because of the better air flow exiting the cylinder because of the opened muffler? And if running stock you should tune to the rpm limit? I'm a noob when it comes to tuning so I'm just trying to understand the concepts better. Thanks!
Best to tune by ear, always. The tach is just objective information. It doesn't "know" how the engine is running. If you tune a stock saw and it's reading 1000 rpm above spec, it can be good to question if everything is ok. I don't worry about the RPM at no-load however. Short high-rpm bursts won't hurt anything and when the real load is on the saw, it's not at high-rpm. The limit's are more about long-term bearing durability and secondary engine forces. The piston isn't going to get hot with no load on the saw. Newer saws actually have rev limiters built into the ignition system. That makes tuning tricky unless you have a way to load the engine while adjusting. (Dyno.... or the trial and error method.)
I got my saws tuned so they 4 stroke most of time. They only come out of it when buried in wood a full bar length and working hard. Is that too rich ?
If you have to sit on it in the wood to get it to clean up, then yes, it's likely too rich. You want it clean and strong when cutting moderate loads.
