husq 445 xtorq poor acceleration and bogging

[goatchin]

I decided to help a friend out that helps cut firewood with me on occasion just for something to do, by figuring out why his 445 is real doggy, at my cost since I sell the firewood, he just helps for free. It starts good and idles good once warmed up, but out of wood, when you accelerate it a little (near half throttle) its ok, but once you try to hold it wide open it bogs and sputters down and will eventually stall out if you keep trying. In the wood it acts the same but wont stall out, just real slow and bogs down to where you have to come out of cut and then restart.

From my first inspection it looked like it was getting choked out by the cruddy air filter, and he said he's never changed the fuel filter. 125psi cold compression. spark plug and piston top is tan/light grey, a little lean looking for my preference. Got those ordered and installed, and cleaned up the intake area of built up crud, no difference.

Fuel line didn't feel too spongy, could that be collapsing? fuel filter looked decent and I flushed out tank.

Are the zama c1m el37 carbs a pain to rebuild or nothing special? Says he uses 91 octane but not sure whether he gets ethanol free or not, so I'd be wasting time just trying to clean it in that case right?

My next step was going to be the fuel line and carb rebuild...$14 for kit, or $31 for new carb, if I spend an hour dinking around rebuilding carb I may as well buy a new?

 

[Thommo]

Check the muffler to see if it is blocked

 

[goatchin]

spark screen is ok, light grey color, openings in center were similar to those on the edges. Are these a CAT muffler or a baffled can?

Looking in from spark plug hole with light, the exhaust port doesn't have much carbon build up. Cylinder walls look good, I'd like to see some more oil sheen to them but no scores

 

[BenK]

I am no master, but could it be a tuning issue?

Maybe the high jet needs tinkering?

 

[cus_deluxe]

I would start w the carb. Should be able to have it off, apart, cleaned and back on in 30 mins or so. Does it have limiters? Adjustable wirh a screwdriver or does it have splined screws? Ive fixed more than one saw with similar symptoms just by backing out the H screw as far as possible, could just be a tiny little piece of debris in there.

 

[Ted Jenkins]

From my experience there is some debris on the screen in the carburetor. It sounds like the saw is not due for an overhaul so clean the carb and likely you will be up and cutting happily. Thanks

 

[goatchin]

Wow those carbs are a pain in the nuts to get off after only dealing with older 372 and 046 style saws haha. Sawdust collected eveywhere so had to do external cleaning b4 getting carb out and afterwards.

The air butterfly control body that is mounted above carb for the split intake had black gunk built up on cylinder side, air box side was clean.

The carb didn't look bad, only debris I found was a few specs of yellow flakes on the screen. Fuel pump side gasket was slightly stuck to body so had to use screw driver to pop cover off, it left behind some residue. Cleaned everything with carb cleaner but didn't pull gaskets off the covers in kind of possibly being stuck.

Needles are splined....I remember reading about using a 12pt socket but don't recall the size, any ideas or alternatives?

Pressure tested fuel line and was ok but doesn't rule out possible collapsing, same with line going from bulb to carb.

Letting it all set for a bit then will respray with cleaner and put together and retry

 

[Ted Jenkins]

You are on the right track. That is why the older saws have such value for me. Yeah the carburetor does not pop off so easily. Be sure that the adjustment screws have been taken completely out and blown clean. If you like the plastic restriction device put it back in or leave it out for full range of adjustments. Thanks