New carb setup question. Husqvarna 545 clearing saw.

[mudfly]

Can someone please explain what the second throttle body is for on this carb setup?



Comes with these funny air intake horns.



It was not tuned remotely close for 10 F degrees and i don’t want to burn it up. I couldn’t figure out what special screw driver I needed to use so I had to remove plastics to get a better look. Why can’t they just use the slotted screws?

 

[Marley5]

Those " horns " are for air and fuel.
Looks like a brand new saw and a professional grade saw.
What's the saw doing to make you think it's not tuned properly for cold weather ?
Do you want to lean it or richen it ?

 

[mudfly]

Those " horns " are for air and fuel.
Looks like a brand new saw and a professional grade saw.
What's the saw doing to make you think it's not tuned properly for cold weather ?
Do you want to lean it or richen it ?

It’s bogging off idle to the point it will die if I don’t feather the throttle, so something isn’t right there. If I can get it up on the top end it screams. So I’m thinking rich on bottom and lean on top. It is new, so I’d rather run it a little rich for the first few tanks anyway.

 

[huskihl]

It’s a Strato engine. Difficult to explain, but traditional two strokes purge the exhaust out with some of the next cycle’s fresh charge. Strato engines suck a layer of fresh air through the piston and on top of the next incoming transfer charge. They use that fresh air on top to purge exhaust rather than purge it with air/fuel. Less raw fuel will be blown out through the exhaust. In your case, that fresh air comes through that top butterfly

 

[Marley5]

Sounds like it's starving and needs more low jet, CCW until throttle response is obtained.
Gotta be honest though, never ran a saw or any other equipment in 10*, wow

 

[mudfly]

Sounds like it's starving and needs more low jet, CCW until throttle response is obtained.
Gotta be honest though, never ran a saw or any other equipment in 10*, wow

Going to be below zero this weekend. I’ve cut firewood in -20F. If you start getting cold, pick up the splitting maul and warm up. Not a big deal unless it’s windy.

 

[pioneerguy600]

It’s a Strato engine. Difficult to explain, but traditional two strokes purge the exhaust out with some of the next cycle’s fresh charge. Strato engines suck a layer of fresh air through the piston and on top of the next incoming transfer charge. They use that fresh air on top to purge exhaust rather than purge it with air/fuel. Less raw fuel will be blown out through the exhaust. In your case, that fresh air comes through that top butterfly

Good explanation, the OP should now google search out strato charged small engines, there are working video`s out there that shows the intake all the way through the cycle to exhaust.

 

[Riverrail]

Can someone please explain what the second throttle body is for on this carb setup?

View attachment 1232749

Comes with these funny air intake horns.

View attachment 1232750

It was not tuned remotely close for 10 F degrees and i don’t want to burn it up. I couldn’t figure out what special screw driver I needed to use so I had to remove plastics to get a better look. Why can’t they just use the slotted screws?

Can someone please explain what the second throttle body is for on this carb setup?

View attachment 1232749

Comes with these funny air intake horns.

View attachment 1232750

It was not tuned remotely close for 10 F degrees and i don’t want to burn it up. I couldn’t figure out what special screw driver I needed to use so I had to remove plastics to get a better look. Why can’t they just use the slotted screws?

My Husky 545 is Autotune. Aren’t they all?

 

[huskihl]

My Husky 545 is Autotune. Aren’t they all?

Yes on the 545 chainsaw. I’m guessing a clearing saw is different

 

[Riverrail]

Yes on the 545 chainsaw. I’m guessing a clearing saw is different

Yep. I had a suspicion but thought that Husqvarna wouldn’t use the same numbers for more than one piece of equipment: 545FX, a heavy duty weed wacker with a saw blade.

 

[Riverrail]

Yep. I had a suspicion but thought that Husqvarna wouldn’t use the same numbers for more than one piece of equipment: 545FX, a heavy duty weed wacker with a saw blade.

Also, I just read their ad for it ( at least the current model,) and it is Autotune as well.

 

[mudfly]

Also, I just read their ad for it ( at least the current model,) and it is Autotune as well.

Well this was delivered to me about 2 weeks ago. I ordered it on the 20% off sale that Husky had in October. They didn't have any stock and had to wait for manufacturing. Not too happy with the delivery time, but that is a different topic. Bottom line, its a very recent build, and it is most certainly NOT an autotune.

 

[Riverrail]

Well this was delivered to me about 2 weeks ago. I ordered it on the 20% off sale that Husky had in October. They didn't have any stock and had to wait for manufacturing. Not too happy with the delivery time, but that is a different topic. Bottom line, its a very recent build, and it is most certainly NOT an autotune.

Dug around a little deeper and I see that I can buy a new 545FR that is x-torque but not Autotune. On a side note, I have a Stihl FS550 clearing saw. I quite like it but it sometimes likes to hesitate or stall when revving up from low idle. I’ve fine tuned its regular carb as best as I can but it can still be a bit iffy. Good luck.

 

[RedneckChainsawRepair]

Just strato like a chainsaw is with same set up. I just recently rebuilt the carb on a 555.

2 I seen in 555 bogged off idle and needed properly tuned. 1 was brand new.