Exhaust when milling

[Brent Nowell]

for the first time yesterday I found that my saw was too hot to touch on the top cover after a pass. I realized the 395 was blowing exhaust directly onto the Alaskan mkiv and my pass was too close to the ground. This lead to the exhaust not getting away from the exhaust...
I also left the saw idling between setting up my ladder and pulling off the slab...

I always let the saw cool at idle after a pass for a minute but then shut it off and setup for another pass. So far this has made the top cover warm to the touch even after a longer pass. Anyone else have this issue with jig and your ground clearance interfering with the exhaust?

Curious if you did anything to remedy this

 

[BobL]

Ground clearance becomes a non issue iff the log is lifted up off the ground when its placed on a slope.



This has the added (unintended) benefit of blowing the sawdust away from the operator so no more shuffling through an ever growing pile of sawdust at the operators feet.

 

[Brent Nowell]

Thx bob, that is a good idea, I could easily braze an attachment like you have made.

Yesterday the wind was blowing in a direction that no matter what position my face was, I was getting fumes in it. Really annoying, gets a good headache going too.

 

[Brent Nowell]

Went to do my saw cleanup for the 395 that was getting hot like I mentioned. Gas tank was almost empty, I have a feeling it was just running lean thus the heat and all..

 

[rarefish383]

Went to do my saw cleanup for the 395 that was getting hot like I mentioned. Gas tank was almost empty, I have a feeling it was just running lean thus the heat and all..

I have had saws get in a position where the exhaust couldn't escape and burned my knuckles, and I mean blistered burned. Not just ,"oh, that's hot". Getting "low" on fuel and running lean doesn't make sense. It will only start to lean out when it starts sucking air. That's out of fuel, not almost, and it will only do that for a few seconds. I've been up in trees and wanted to finish a cut, and feathered the choke in and out to get a few more seconds out of the tank. When you have a notch cut in a log and you are nine tenths of the way through the back cut, you don't want to pull the saw out of the cut and send it down for fuel. Especially if you are 60 feet up, making a 24" cut with a Super 1050 with a 36" bar, hanging on your saddle.

Now, if the saw is starting to rev up without pulling the trigger, "Leaning Out", while on it's side on the mill, that' a sign of bad seals sucking air, and that will cook it.

Your statement, "it was just running lean, thus the heat" doesn't make sense either. In commercial use saws run till they run out of fuel every day, if that caused them to run lean, they wouldn't last a week.

If the saw is running well, I would suspect that it was just in a position where the exhaust couldn't escape and got the exterior hot, no harm every now and then. Try to get the log off the ground. I've had to mill a log now and then on the ground and the last couple cuts got real hot. If you have to dig a little hole under the uphill side and slide a floor jack under it, jack it up and slide a piece of wood under it. If you have a pick up truck I can show you lots of ways to get a log up in the air.

 

[Brent Nowell]

I have had saws get in a position where the exhaust couldn't escape and burned my knuckles, and I mean blistered burned. Not just ,"oh, that's hot". Getting "low" on fuel and running lean doesn't make sense. It will only start to lean out when it starts sucking air. That's out of fuel, not almost, and it will only do that for a few seconds. I've been up in trees and wanted to finish a cut, and feathered the choke in and out to get a few more seconds out of the tank. When you have a notch cut in a log and you are nine tenths of the way through the back cut, you don't want to pull the saw out of the cut and send it down for fuel. Especially if you are 60 feet up, making a 24" cut with a Super 1050 with a 36" bar, hanging on your saddle.

Now, if the saw is starting to rev up without pulling the trigger, "Leaning Out", while on it's side on the mill, that' a sign of bad seals sucking air, and that will cook it.

Your statement, "it was just running lean, thus the heat" doesn't make sense either. In commercial use saws run till they run out of fuel every day, if that caused them to run lean, they wouldn't last a week.

If the saw is running well, I would suspect that it was just in a position where the exhaust couldn't escape and got the exterior hot, no harm every now and then. Try to get the log off the ground. I've had to mill a log now and then on the ground and the last couple cuts got real hot. If you have to dig a little hole under the uphill side and slide a floor jack under it, jack it up and slide a piece of wood under it. If you have a pick up truck I can show you lots of ways to get a log up in the air.

I see what your saying, but is it possible the pickup was out of the fuel that was left in the tank? There was very little left when I checked.
I also noticed a huge power drop when it was happening.

We will see what happens on Saturday when I go out again.

 

[rarefish383]

Not likely, and when a saw runs lean you know it. I've only had it happen once when a screw came out on top of the carb. When it started sucking air it went wide freaking open with out touching the trigger. I'm not talking about like when it's adjusted a little lean. When it starts sucking air, it's like someone just flipped the switch on the nitrous bottle. I did have it happen on another saw too. That was an XL924, but I knew the symptoms by then, and shut it down. The 100CC Super 1050 that went wild when the screw came out, I kept running one or two more cuts to finish the job, and switched it off. Then it never started again.

As far as the fuel line being bent, or crooked, so it comes out of the fuel when it's on it's side is possible. But, I had that happen with a Homelite C5 when milling, and it would just run out. You could take it off the mill and start it up and buck a few pieces of a log. It was only good for about 3/4 of a tank when milling, then run out.

I'm still betting on the exhaust not having room to dissipate. Now, if it is running lean for whatever reason, you don't want to run it till it's fixed, it will melt down. Run it in a normal upright position first. If it runs well, then stick it on the mill and give it a go. When mine started sucking air they did NOT loose power. If anything they felt like they gained power because they started to race uncontrollably. I'm not a saw mechanic. When we were in business we paid a mechanic. If you were a climber and your saw died, you got another one and went back to work, you didn't tie up a whole crew doing the mechanics job. That being said, I'm pretty good at guesstamating what's wrong with a saw. Keep us posted.

 

[Brent Nowell]

Thank you for the info, looks like an exhaust flow issue as originally noted.
I’ll have to elevate my milling this weekend allowing the saw to breathe a bit better

 

[BobL]

I see what your saying, but is it possible the pickup was out of the fuel that was left in the tank? There was very little left when I checked.
I also noticed a huge power drop when it was happening.

I've had that happened to me a couple of times and its definitely been caused by the fuel pickup point being out of the fuel, but like rarefish says I've seen an increase rather than a decrease in power. The temperature shoots up far quicker than normal running so its not something you want to do for more than a few seconds.

 

[rarefish383]

Bob, did yours keep running for an extended time? My C5 started to lean out for just a couple seconds at most, and ran out, just like running out when bucking firewood.

 

[BobL]

Bob, did yours keep running for an extended time? My C5 started to lean out for just a couple seconds at most, and ran out, just like running out when bucking firewood.

Mine happened a few times with the 076, it's never happened on the 880. Turbo mode lasted no more than about 15s , slowly getting more turbo like and then it stopped when too much of the filter was out of the fuel. With the 880 its possible to refuel mid slab so I've always made sure there was enough to finish the cut.