460 problems

[mxracer]

hello , my dad has a ms460 that dont want to idle down. it seems to rev good but when you let off of the trigger it just wont idle. the carb adj. dont seem to make that much difference. can any one help?

 

[Hired Gun]

The idle adjust has no effect? Sounds like a pressure test to check for air leaks may be a good place to start.

 

[mxracer]

if you back out the idle screw it just shuts off.

 

[CaseyForrest]

As suggested, pressure and vac test. Sounds like you have a bad seal somewhere. Maybe crank seals, or carb gasket, maybe impulse hose or intake tube...Could be as simple as the carb being loose.

 

[mxracer]

good point

i think that is where we'll start.

 

[fishhuntcutwood]

It stays at higher rpm's and won't idle, or the rpm's drop and it won't idle?

If the rpm's stick high, easiest thing to check would be a gummed up throttle arm on the carb, or something stick in the trigger/linkage.

Jeff

 

[mxracer]

after you rev it up, when it should come back to idle it just shuts off. also it seems to hesitate when you start throttling, like a low speed adj. should fix, but even with the limit caps off it wont correct the prob. it doesent seem to change anything.

 

[stihltech]

idle

Check under the air filter bottom housing. Remove 2 nuts to pull it off. Clean out all the sawdust around the carburetor.
pay attention to the throttle linkage on the side of the carb.
I have seen it pack under there and hold it open.

 

[THALL10326]

after you rev it up, when it should come back to idle it just shuts off. also it seems to hesitate when you start throttling, like a low speed adj. should fix, but even with the limit caps off it wont correct the prob. it doesent seem to change anything.

Hmmmmmmmm did it just start doing this all the sudden or has it been getting worse and worse???

 

[Lakeside53]

If it's not the throttle sticking... then air leak is most probable. If I was to stab in the dark, flywheel side crank seal or impulse hose, but check all the simple stuff first.

 

[911crash]

had a similar problem with my 460, problem i believe was with the clutch i'll double check tommorow my saw was about 2 monhs old and it would idle fast enough to spin the chain. good luck

 

[mxracer]

all of the tips are very helpful and i'm kind leaning toward an air leak, i'll get on it tomorrow. is there any other way to check for a leak other than with a vacuum pump. this may sound dumb but could you use either. i've used this to find VGA. leaks on a cars. when you spray it onto a leak the engine speeds up. can be dangerous though... a bad plug wire will make a carbeque

 

[stihltech]

cheap test

Get some wd 40 with the straw. Remove the top cover. CAREFULLY spray around intake and pulse hose area, behind flywheel. I did say carefully! If there is an air leak the speed will change dramatically.