Straight gassed

[ANewSawyer]

A Mityvac is a must have. Small two strokes are just air pumps, is something I have read on here. Took me a little while to under stand why but it makes sense.

 

[Al Smith]

As a note,you are better to use something like 3M green pads and kerosene than emery cloth .The emery will eat right through the plating while the green pads will only take the aluminum transfer off .

 

[Daserlon]

Like i said, i've never even seen a press/vac test. I dont know whats involved. Enlighten me please.

 

[beaglebriar]

Block off the intake and exhaust with some rubber (inner tube works well). Then pull vacuum or pressurize through either the sparkplug hole or the impulse line. Just remember to plug off whichever one you're not using.

I use the sparkplug hole most of the time with an adapter made out of an old plug and a hose barb.

Loosen the carb and muffler and slide the rubber in between each side . Then tighten them back down to create a seal.

Get some soapy water and squirt it around to find leaks.

Pull the flywheel and clutch/oil pump before testing so you can check the crank seals.

Clear as mud???

 

[Daserlon]

I'm not much of a mechanic but i think i understand and thank you for the info/help.

 

[MustangMike]

Piston burned on just the exhaust side is (like Lee said) usually a "lean" failure, straight gas would score both sides.

May have been adjusted too lean, have an air leak (don't want to put it back together w/o finding it if you do), or may have just been pushed hard with a dull chain.

Should be able to clean the cylinder up with sand paper and a drill (there was a thread on doing it). If acid gets under your plating, it will ruin your cylinder.

I have brought several cylinders back to life this way, all are still running (two are being used by a tree pro).

 

[MustangMike]

Here is Randy's video on how to do it:

 

[Daserlon]

Thanks to you too for the info. I think this cylinder doesnt have transfer just scored. I'll try removing cuz i've never tried it before. Nothing to loose cuz i think its junk already. On a good note after watching randys video i think i can save a couple of my other questionable cylinders. 1 is a 181se, other is 281. I checked the 3rd and it's good. I thought it a 281 also but I belive it to be a 288 cuz the 181 piston/ring is way loose in it. Bonus!

 

[MustangMike]

Usually, the only time you can not save a cylinder is when metal has gouged it. The nikasil plating is very tough, and aluminum transfer can be removed w/o damaging it.

 

[7sleeper]

Putting a saw together without pressure and vacuum testing is madness. It can get expensive quickly to skip that step...

Sorry but I do not agree. If you are doing a overhaul just replace the bearing seals too. Depending on age(>10-15 years) I would replace the rest of the "rubber" parts(intake, fuel lines, etc.) as well if the saw is a "keeper".

7

 

[Al Smith]

Even if some of the plating flakes if it's not in the ring travel you are pretty safe .

A piston if it isn't too bad can sometimes be saved .A low spot usual won't hurt it too much .A high spot will displace the oil film and most likely fail again .

I've saved so pretty toasty pistons and cylinders .3M green on the cylinder and 20 micron lapping paper with kerosene on the piston .New rings,run it .As far as I know they are still out there cutting firewood .

 

[Al Smith]

Now kiddies a story .Some time back John Lambert better known as Gypo Logger,Franks Planks,Yukon John and half a dozen more on line names souped up a brand new 044 Stihl .For whatever reason he hung that thing three times .Got to work with the sand paper and resurrected it again .I ran that thing and it did good even after all that .Never say die .

 

[Mark71gtx]

Sorry but I do not agree. If you are doing a overhaul just replace the bearing seals too. Depending on age(>10-15 years) I would replace the rest of the "rubber" parts(intake, fuel lines, etc.) as well if the saw is a "keeper".

7

I pressure and vac test even after all of that is replaced as well. I have found leaks after all of those items had been replaced as well. Once again, it is crazy not to test.