ms 460 muffler munchin madness

[woojr]

couldn't resist the title. well after reading the muffler mod stuff for a week or so I started defiling my 460's in hope of finding the power I hoped to find. Well, all scientific calculations out the window I guesstimated an increased outlet opening about 2/3 to 3/4 the size of the exh. port. Drilled some holes in the internal deflector and welded (old fashioned oxy/acet), a larger deflector over the original.
I find the saw performs much better but I have a question that someone might be inclined to comment upon. Why does it run noticeably stronger after it has run for awhile? Is it simply something to do with just warming to optimum operating temp? Is it associated with the Stihl inteli carb? Is it the filling up of the air filter? Other? All? I'm really curious because I haven't noticed what appears to be such a leaning out as its used, like this before. This is my first larger Stihl saw.
I don't know if I should take more out of the muffler? Add another pipe on the other side? I am taking it a little at a time.
And oh, yes I did have to richen it some, but I am still within the limited setting.
Also curious as to how many pulls you guys (460 owners) are experiencing for cold starts. And if you use the decompression valve all the time. I find it starts better hot and warm without it. Thanks, Woojr

 

[Lakeside53]

When you say "still within limits", are you talking about the carb limiters or the allowable rpm range of the saw? You really shouldn't mod a muffler and test the saw without taking off the limiter caps and them adjusting quite a bit richer...particualarly the top end...

As for working better after time, not sure... once the saw is warm (couple of minutes max) it should work fine. If it turns out that you're relying on the air filter blocking enrichen the mixture, you're too lean and well on the way to cooking your piston...

 

[woojr]

Thanks for the insight. By limits I mean the limiter caps. When I opened full
throttle, it garbles some without a load. Under the load (24" fully buried in mid hardwood) it just pulls better after it runs awhile. Don't have a tach, I just go by the balance of power in the cut and a little no load full speed garble.
I guess I am looking for some theory more closely associated specifically to Stihl fuel systems. Have no experience with "intellicarb?" Also trying to get a sense of whether to add another muffler port. I'm certain removing the limiter caps will be necessary if I do. Thanks again, woojr

 

[Lakeside53]

Thanks for the insight. By limits I mean the limiter caps. When I opened full
throttle, it garbles some without a load. Under the load (24" fully buried in mid hardwood) it just pulls better after it runs awhile. Don't have a tach, I just go by the balance of power in the cut and a little no load full speed garble.
I guess I am looking for some theory more closely associated specifically to Stihl fuel systems. Have no experience with "intellicarb?" Also trying to get a sense of whether to add another muffler port. I'm certain removing the limiter caps will be necessary if I do. Thanks again, woojr

Ignore the "intelli-carb" - it just slightly leans out the mixture as the air filter gets blocked... With a clean air filter, it behave like a "non-intelligent" carb.

I would go adding ports unless you get a tach... and remove the limiter caps for adjustment. Right now you're likely hard up against the rich end of the stop, and if you have changes in other variables like weather, you may end up lean. Take out the H cap, slice of the tab on the side, then reinsert it. Now you have full range adjustability, but, Caveat Emptor...

 

[MS-310]

Take out the H cap, slice of the tab on the side, then reinsert it. Now you have full range adjustability, but, Caveat Emptor...


Whats the best way to remove the caps? I kinda used a "screw puller" when i did my 310 (drywall screw).

 

[Lakeside53]

Take out the H cap, slice of the tab on the side, then reinsert it. Now you have full range adjustability, but, Caveat Emptor...


Whats the best way to remove the caps? I kinda used a "screw puller" when i did my 310 (drywall screw).

Same way, but line up the tab with the slot before trying to pull. I just use the $5 stihl tool..

 

[Patrick62]

I did mine last year

I wanted to stay "legal" so I opened it up as much as I could and still have the spark screen functional. Like you, I welded (oxy acy) a cone? Ear? Director? whatever to it so as to direct it. Works like a charm. Lots more power. I have not removed my limit caps, found enough adj.

Starts? 2-3 pulls cold and she pops. Kick the choke off, and 1 maybe 2 pulls and it runs. 5 seconds after that it will sit there and idle with a throaty growl

-Pat