050 051 075 076 Info Thread

[Rockfarmer]

Yes I don’t know a lot about porting and muffler mods. I do know that I dismantle a lot of saws. The main reasons I see for piston failure are loose jug (lean), loose intake (lean), loose muffler at the jug (the worst of piston transfere and ring and jug damage) which suggests to me that some back pressure is needed. Know I will admit I know little and hope to remain very teachable and open minded about all aspects of everything! Thank you B

 

[bulletpruf]

I'm thinking the loose muffler allows dirt, sawdust, soot, etc, to enter the cylinder, causing the damage that you're seeing. I don't see how a lack of back pressure would cause this.

Anyway, now I'm anxious to cut open a muffler so I can modify it a bit. I have one that was modded by the previous owner, a few aftermarket ones (Saegenspezi), one from an 051 (maybe smaller port? Have to check), a few OEM from 075, and then a few 076 mufflers that have the different opening.

How many different types of OEM mufflers have you seen?

Scott

 

[Rockfarmer]

I'm thinking the loose muffler allows dirt, sawdust, soot, etc, to enter the cylinder, causing the damage that you're seeing. I don't see how a lack of back pressure would cause this.

How many different types of OEM mufflers have you seen?

Scott

Well respectfully I must disagree, imho. At several thousand rpm’s the saw is pushing a massive amount of c.f. of air through it when running. Nothing is going to enter the cylinder through the exhaust port. Yes a loose intake, absolutely, anything’s possible and loose jug, yes. Most of the loose jugs I’ve come across have “been worked on”. You’ll see silicone gaskets and stripped rod threads ect.

As far as oem mufflers I know of two offhand but have to check media cat to be sure. The old 075 had the thinner box with the 4 slats at the bottom which I’m told breath better than the newer style. The new style has a larger expansion chamber which I feel is better for 2 strokes. Look at any hot saw or sled mod and you’ll see much bigger mufflers. Look at all these chopped Honda’s running around with wicked loud exhaust and you see black smoke indicating burning up valves. Now I realize we are talking piston port on the saws but if you ever ran one with no muffler you’ll see fire. This fire leads to premature piston failure as the heat is too much for the ring grooves and the piston will melt. I’ve got a box of proof. So this leads me back to how do we ride the edge of mod/high performance without internal damage? Another thing is gas. More octane is not better for a 40 year old saw. It is better for built motors with high compression. These old motors were meant to run on leaded fuel, a lubricant. Take that away and add alcohol (an explosive detergent) and again fire passing through the exhaust port and piston failure. Treat these old horses well and they will last longer than we will!

 

[WidowMaker_1]

Scott Not shore If I still have the pictures of the mod process, there not on my phone anymore but they could be on the laptop where I dump me pictures Sometimes? No carb mods needed just richen the H, and L up, I'll pull it out for a run when I get the chance and take a video

 

[bulletpruf]

Well respectfully I must disagree, imho. At several thousand rpm’s the saw is pushing a massive amount of c.f. of air through it when running. Nothing is going to enter the cylinder through the exhaust port.

I don't think dirt and debris is going to enter when it's running, unless it's idling. More likely when the saw is bouncing around in the back of a pickup or something like that.

Look at all these chopped Honda’s running around with wicked loud exhaust and you see black smoke indicating burning up valves. Now I realize we are talking piston port on the saws but if you ever ran one with no muffler you’ll see fire. This fire leads to premature piston failure as the heat is too much for the ring grooves and the piston will melt. I’ve got a box of proof. So this leads me back to how do we ride the edge of mod/high performance without internal damage? Another thing is gas. More octane is not better for a 40 year old saw. It is better for built motors with high compression. These old motors were meant to run on leaded fuel, a lubricant. Take that away and add alcohol (an explosive detergent) and again fire passing through the exhaust port and piston failure. Treat these old horses well and they will last longer than we will!

Black smoke while running is caused by a mixture that's too rich. Constant blue-gray smoke (and distinctive smell) when running is indicative of worn rings. A puff of blue-gray smoke on startup indicates worn valve guides or seals.

Whatever the case, on a 4 stroke car engine, insufficient back pressure will not hurt an engine. It will cause a drop in torque and low end hp, but it won't hurt it [EDIT - you still have to ensure you're not leaning the saw out if you've reduced the back pressure, of course]. FYI - I've been wrenching on hot rods and building street/strip motors for my cars for decades. Have run quite a few with open headers, and that certainly isn't detrimental to engine life.

 

[bulletpruf]

Scott Not shore If I still have the pictures of the mod process, there not on my phone anymore but they could be on the laptop where I dump me pictures Sometimes? No carb mods needed just richen the H, and L up, I'll pull it out for a run when I get the chance and take a video

Thanks!

 

[Rockfarmer]

Another horse ready to leave the barn!

 

[PogoInTheWoods]

Looks like another thoroughbred, too. Very nice work, sir.

 

[diesel&coffee]

WILL IT ISN'T MUCH / NEEDS A LOT OF WORK - BUT IT'S A 076

 

[Rockfarmer]

Brand new!!! Nice!!

 

[PogoInTheWoods]

Still have the box, too? Yikes!

 

[diesel&coffee]

Is there sticky or place I can get all the tech bulletins noted around here??

 

[PogoInTheWoods]

I might know a guy...

 

[diesel&coffee]

DID SOMEONE ASK ABOUT A BOX

 

[Ted Jenkins]

Now what do I do since I have no boxes? I have a 070, 075,and 076 that have not been touched for years. Coming up with a box for them seems impossible though. Last year I restored one of my 056 magnum and have been using it with joy. When I cleaned up one of my bigger bore saws what a difference. With a high quality 404 chain they can really move through a pile of wood fast. So now am determined to get all my older monsters running well. Thanks

 

[Rockfarmer]

I’d rather use a 90+ cc saw that revs less (076 Super for example) than a smaller high reving saw while bucking wood. True I get free wood that’s usually too big for everyone else and I have to rip chunks to manage and handle. 22 lbs weighs nothing to me on the landing I just set it on the log a pull the throttle!! Ha! That chain buries me in chips and I grin from ear to ear! Hiking though the woods felling I might go lighter and newer but I don’t so no worries.

The box is kind of cool though I got to admit!!

 

[PogoInTheWoods]

Speaking of boxes..., check your inbox, diesel.

 

[rebuildinSawin]

Hey guys, how much resistance should there be on the sprocket if you turn it by hand (no chain etc)?
Should it spin freely a few times?

Mine doesn't, I can turn it by hand easy enough but it stops almost instantly, unlike my other saws that engage the oiler at > idle speed...
There just seems like a bit too much resistance.

I know the oiler is driven from the worm gear blah blah and i've checked that the sprocket is not being bound up on the clutch drum etc which can happen if sprocket + clutch parts not installed correctly.
I don't want to pull the oiler out unless there definitely is an issue because of the high prices i've seen of replacement parts incase i bodge it.
Saw has had used diesel truck oil used as bar oil for a time i think.

Long story, I just fixed an air leak in the saw (crack in clutch side inner seal) & making sure i've got everything else that needs doing at the same time.
This was looking into the clutch side bearings when i first took off the old seal... Not terrible for probably 30 years of use, or is it?


Thoughts? Slow bar oil leak into crank case? Nothing leaked in that i could see while i left it there for a few days after cleaning off all the curd.

Cheers

 

[Rockfarmer]

Short answer, no it’s fine.

That looks like normal carbon crud. With stethoscope if no howl is heard in the bearing it’s fine. I like to turn the oil piston by finger when exposed like in the pic or on assembly and make sure that spins freely, if it doesn’t that’s a problem. You’ve just installed a new pto seal and I assume an Oiler drive seal. That’s two new tight surfaces that seal so no you don’t want that clutch hub to spin with the wind or you’ll be sucking air. All my new builds or rebuilds are exactly as you describe. You can turn easily but with a little resistance and no free wheeling. Other clutches are designed different. I like about 3-4 mm of lateral play in clutch hub after I tighten the spider down.

Cheers!

 

[rebuildinSawin]

Thanks Rockfarmer!

I like to turn the oil piston by finger when exposed like in the pic or on assembly and make sure that spins freely, if it doesn’t that’s a problem.

So how freely are we talking? give it a flick and it should spin a few times, or just move with minimal resistance? and you are saying move the actual oiler piston shaft thingy, not the oiler drive worm? hmmm... I think my oiler piston doodad would just rotate smoothly, but wouldn't free spin by itself. I guess this is also going to depend if it is trying to pump oil or air.

Of course i've put the new seals in now so i can't double check, which was probably a bit silly.

Yes so far bearings look ok. It cleaned up pretty alright actually. Good to know the crud was probably just carbon. And yes on both new seals. No more air leaky! :-D