Kick myself in the butt! 371XP smoked

[GASoline71]

Tuned in the lowlands, it will run RICH in the mountains. That's why you've had no problems.

Tuned in the mountains, it will run LEAN in the lowlands.

10-4... makes sense...

I have the small screwdriver in my tool kit... but it rarely if ever sees a carb. The 028 I have was bought brand new by my father in 1984... the saw has seen countless cords of wood, and has only had the carb serviced once by the same shop the ol' man bought it at. I personally have never touched the carb on that saw and have had it in my aresenal since 1995... runs like a champ.

Gary

 

[bitzer]

10-4... makes sense...

I have the small screwdriver in my tool kit... but it rarely if ever sees a carb. The 028 I have was bought brand new by my father in 1984... the saw has seen countless cords of wood, and has only had the carb serviced once by the same shop the ol' man bought it at. I personally have never touched the carb on that saw and have had it in my aresenal since 1995... runs like a champ.

Gary

My uncle says the same thing about his older saws, but I think where ethanol in fuel is rampant (like where I am in SE WI), the saws and other two strokes have needed a lot more maintance in the last 4 or 5 years. I use 93 octane and only use fuel within two weeks of buying it on my saws. Even with that I think the ethanol causes problems that didn't happen with straight gas. In my grandpa's pontoon boat where fuel sits for several weeks during the summer(even heavily stablized) it seperates and clogs up the fuel lines, filter, and carb jets. Up until three years ago that motor never had a fuel problem and now I service it every year with new filter, lines and carb cleaning and it only sees about 3 months of action a year!

 

[redprospector]

Here we go. My buddy says, hey there is a big old Oak that fell down off the Hwy up here, let's go get it. Okay, throw the 371XP in his truck, and we are off. The Oak was big, prolly 40-46" dia., I fire up my saw, running like a mad dog. Chips are flyin, the saw is just screamin (unlimited coil)He is impressed. My saw is runnin better than it ever had.

Then, my buddy says, the barks burnin. HUGH? I shut her down, sure enough, smokin bark. I'm thinkin, this is not good. Well, that place on the Hwy was about 2500', I usually cut at about 5000". I should have checked carb settings, I didn't. Smoked the piston, sheet! It was getting late, we were in a hurry.

Carry that carb screwdriver with ya, and check your settings when changing elevations. Another lesson learnt the hard way. Dangit.

Scooter, this little tidbit won't help your 371 now, but I'll give it to ya anyways.
When you find yourself without your carb screwdriver, you can take a round file and beat the small end flat with a hammer using your trailer hitch or ball as an anvil. It works pretty good, and if you have a flat file handy you can even make it pretty.
I live at 8600' elevation, and if a saw is tuned at the "edge" here and I go to 7000' to work, I,d better richen it up when I get there. I generally run them a little fat at home so I don't have to mess with it.

Andy

 

[Evan]

i was worreid about ,u fixed H 026 recently. i live at 3200 the saw is muffler modded as a tiny hint of burble hear its slight enough i watch it very closely when cutn at home. it runs perfect at 6500-9000

but i was conserned about it running lean at sea level so i put thye factory muffler cover off the 260 on it for the trip the coast. i never did get a chance to use it down there but i did run it at home alittle but and the stock exhaust is very restrictive. just swapn to my modded cover puts a huge grin on my face. i can see why every one says they are turds.


while buckn wood with my 372 and 044 i do make sure i can detect a burble every so often when i lift the saw to get another bite on the dawgs exspecialy in big wood where the saw is in the cut for awhile

 

[scootr]

"I wonder if the muffler ports face the wood and the excessive lean heat was torching it? "


Exactly, the muff is one that has a tube at about 30% angle, pointing at the wood. I was watching the end of the of the bar, a 32 runnin full skip. This was a tree that had been through a fire and sat for years. It is dry, and hard as hell. The saw was working harder than I can remember, and it was a new chain. This was some mean wood, prolly why it is still there!

I pulled the plug, half was dark, the other half had aluminum on it. I try to run my saws a little fat. This is an older saw, may be time for seals. I recently put an aftermarket brake band on it, it does not fit like OEM. The bends are not as sharp as the OEM, it rubs on the top of the drum a little. I wonder if it got so hot it cooked the crank seal? I build a lot of saws, this is the first one I cooked. I will tear it down this weekend and report back, maybe save someones saw from my mistake.

Oh yea, I was using Stihl orange bottle oil @ .9 gal premium per 2.6oz.

 

[THALL10326]

Here we go. My buddy says, hey there is a big old Oak that fell down off the Hwy up here, let's go get it. Okay, throw the 371XP in his truck, and we are off. The Oak was big, prolly 40-46" dia., I fire up my saw, running like a mad dog. Chips are flyin, the saw is just screamin (unlimited coil)He is impressed. My saw is runnin better than it ever had.

Then, my buddy says, the barks burnin. HUGH? I shut her down, sure enough, smokin bark. I'm thinkin, this is not good. Well, that place on the Hwy was about 2500', I usually cut at about 5000". I should have checked carb settings, I didn't. Smoked the piston, sheet! It was getting late, we were in a hurry.

Carry that carb screwdriver with ya, and check your settings when changing elevations. Another lesson learnt the hard way. Dangit.

Speed kills. If its running with a scream its running lean...

 

[scootr]

Whatcha think?

Here is a pic of the plug. Doesn't look like it was running lean. What do you think?

 

[blsnelling]

It doesn't look lean, but what are all the deposits on it?

 

[scootr]

Good ?

We have 2 gas stations up here, a Valero and a 7-11. Not the best fuel. Think crappy fuel with Ethanol would do this? I mix .9 gal 93 oct. with Stihl oil, don't use old fuel. There are no name brand fuels up here, have to drive down the mtn to get Shell or Chevron.

I will put some pics of the jug and slug after I tear it down, maybe Sunday.

 

[dragrcr]

I dont think 2500 feet is going to burn up a saw, especially in cool weather.


Perhaps a tad lean to begin with..

Did you look in the ports to see that it wasa toast?

hate to say it, but the colder weather, as long as it was relativly low in humidity, actually hurts a lean saw.

 

[Justsaws]

Guessing by the looks of that plug that saw has other issues than being slightly out of tune. That plug had a lot of build up on it that was just starting to burn off. Better check the saw out as that plug looks like it came from a saw that was fat to compensate for other issues.

Start with the basics and work through the saw.

 

[056kid]

Keep in mind that just cause the exaust is burning wood, dosent mean that the saw is lean...

 

[injun joe]

sorry guys but what does it mean to be 4 strokin at wot. i understand while it is idling and im not understanding the burbling whilst cutting.

 

[Justsaws]

sorry guys but what does it mean to be 4 strokin at wot. i understand while it is idling and im not understanding the burbling whilst cutting.

Should not be burbling will making the cut, typically.

If you hold the throttle wide open with no load and dial in the high side and set it where it just starts burbling consistently that will usually be about correct. It should even out to no buble during the cut. Limited coils and crappy old school fuel governors make it more difficult to tune WOT no load.

Some manufactures want the saw tune WOT with no load and some want the saw tuned under load. In the old days the Homelite 330 was tuned no load WOT and the Mcculloch 10 series was tuned WOT under load.

 

[dingeryote]

hate to say it, but the colder weather, as long as it was relativly low in humidity, actually hurts a lean saw.

Agreed,
But looking at the plug here is heavy ash build up as if the saw was running very rich previously, and for a good while. Enough so that the cold and elevation change likely wouldn't matter.

Lean is lean.
Something ain't right besides the carb setting.

I talked to a dealer today that just replaced the pistons on 3 different 372's from the same crew. Each with thier own mix cans, all of 'em bought gas at the same rural station. Ethanol tested out at 18%!! Making matters worse is the seasonal stabilizer present, was way too high in volume as well.

Wierd stuff like that plug make me wonder about fuel.

Stay safe!
Dingeryote

 

[dragrcr]

I dont think alcohol caused that, I would almost say that it was run with heavy oil, or maybe even a non ashless oil like 30w or something like that at one time. Also what is the gap on the plug now, maybe too closed, and causing incomplete combustion? when you say it toasted the piston, what exactly did you find in there, if it was running great then i doubt anything could be too bad in there, but always let the saw rev easily with no load, dont hold it wot, but just rev it a bit to let the fan cool the head before you shut it off.

 

[bitzer]

Here is a pic of the plug. Doesn't look like it was running lean. What do you think?

The plug looks a little blistered to me from excessive heat. The deposits could be carbon that originally deposited when running richer and then from the excessive heat from the lean mix may have cooked them on. Hard to say from a pic tho. The color does not seem natural, like a brown or gray or even white (from being lean). Looks a little reddish. The engine was obviously running really hot to be cooking the wood.

 

[bitzer]

Keep in mind that just cause the exaust is burning wood, dosent mean that the saw is lean...

I would agree with that, but my ports are pointed right at the wood to keep chips out of my face in the wind and on some long cuts I have had hot wood and an occasional smoking, but nothing burning. I often cut dead trees that have been left standing and dry for a while, sometimes the exhaust blows the bark off and sometimes it makes it real hot, green wood I have not had a problem other than getting a little warm. I also have 2" dogs on the saw which give it some distance from the wood. Lots of variables here I guess. Thats just my experience. I'm sure it could happen and I've heard of starting bark on fire just never seen it.

Pics of the piston and jug should give a better insight.

 

[dragrcr]

I get bark to the point that it is smoldering all the time with my 440. dont look like it was "heat blistered" to me, never heard that term before when talking about a spark plug, color looks typical to me. not lean and not hot.

 

[scootr]

I always run Stihl orange or Husky XP oil, .9 gal 93 oct. to 2.6 oz.

I don't mix a lot of fuel at one time, try to keep it fresh. If it sits for a couple months, it goes in the Dakota. Commiefornia has some crappy fuel, smog B.S.
I wonder if they have switched over to the winter formula, it is Oxygenated.
Ethanol and Oxygenated??? Maybe contributed to it. The piston is scored on the exhaust side, I'll pull the jug and post pics. This sucks, that slug only had about 30 tanks run through it.

Maybe big bore time, that would make me feel better.