ArboristSite.com Sponsors


Carb tuning after muffler mod ms460

strawmyers

strawmyers

ArboristSite Lurker
Joined
Aug 20, 2016
Messages
5
Age
38
Location
Indiana
Just tripled the size of the opening on my stock muffler can; and also added the dual port front cover to my ms460. I read several threads on here to try to prepare myself before doing this mod. Cut the tabs off the limiter caps. Put the high and low screws to a light seat, then backed off each one 1 1/8 turns counter-clockwise. Saw won't start. definitely seems like its flooding. I backed the low screw down to 1 turn, then to 3/4 turn. Backed the high to 1 turn. Its at least popping the decomp valve every few pulls, now; but still not starting. Thought I should check on here for advice before I go any further. I don't want to lean things out too far. Also, I did not touch the LA screw at all as I didn't see anything about that in the threads that I read. Should I be seating it and backing it off a certain number of turns? Thanks in advance for the help!
 
strawmyers

strawmyers

ArboristSite Lurker
Joined
Aug 20, 2016
Messages
5
Age
38
Location
Indiana
La is your idle speed
Dry the plug and cylinder
Air it out should start at one turn out



Sent from my iPhone using Tapatalk
When I took out the spark plug to let the cylinder dry out, it looked pretty shot. Went to town and got a new NGK plug and reset both screws to 1 turn and it fired right up. I tweaked the LA screw to get the idle up to where the chain just started to advance, then backed it off 1/4 turn. Oddly, adjusting the low screw once its running seems to make no difference. I even turned it all of the way in to where it was seated and then to 3 full turns out and it didn't make a bit of difference either audibly or on the tach.


[edit] Wow, talk about a stupid mistake. I had taken that rubber grommet out earlier and had the H and L screw locations backward in my head. Figured I'd own up to the stupidity instead of just editing the original post. I'll get back to tuning and update when I get somewhere. Thanks again for the help.
 
strawmyers

strawmyers

ArboristSite Lurker
Joined
Aug 20, 2016
Messages
5
Age
38
Location
Indiana
Okay, current idle is set around 3000. Got it to 4-stroke to just above 14000 and backed it off to 13750 where it 4-stroked steadily. Buried the 25" bar in a 30" maple trunk. 4-stroking stops in the cut and the saw maintains 10-11000 rpm in the cut if I'm not leaning on it. Allows me to lean into it; but then rpms drop to 8500-9000. How does that sound?
 
Top