Cleaning Out a Jug

Old Monkey

Mar 9, 2005
I recently put a big bore piston and jug on my 046. The saw ran for a few tanks and died. I pulled it apart today and the piston was heavily scored on the muffler side only. I am told that is what it looks like if it burnt too lean. I am going to keep the jug and replace the piston. I was told that I should go get some muriatic acid from the hardware store and clean the inside of the jug with it and then use a fine grained wet/dry sand paper to finish it off. Does this sound right? Any tips on getting the clip out that holds the piston on? I used my dremmel too last time and just cut it.
Never used the acid part. Just wd-40 and 600 grit wet/dry sand paper. Flush it good with the wd-40 when done.

Is the jug scored at all? Or was just the piston?
XS flat screwdriver. I can usually get them out without ramming the screwdriver through my thumb more than once. But the blood seems to help give you more traction. ;)

Definitely check your carb and intake boot. If you've burnt up two pistons then you're obviously running lean for some reason. Replacing another piston without fixing the root cause will be money wasted.
Never done the muratic acid either, but from what I understand (LOTS OF FRESH AIR!!!!) Dump little in, let it eat for a bit, then rinse well with water.
When you sand, make sure you DO NOT go up and down, go in a circular motion with the jug!!! Up and down will create micro scores and the rings will never seat (seal) properly.
Also, take some fresh mix and rinse the heck out of the crankcase a couple of times to get the shavings out.
A small screw driver for the clip. Sometimes if you grind a tiny V-notch you can hook it with the notch and get it. Also an O-ring pick set can come in handy for that. Use the straight one to pop it down, then the hooked one to pull it out.
And Brian is dead right!! Something is wrong!! Are you using a new base gasket? If you want I can get you the Locktite number for the anerobic sealer, mabe a bit of that on both sides of the gasket for insurance?
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  • #5
The first jug and piston were fine. I replaced them because the threads for the spark plug were stripped out. There is scoring in the jug but the fellow from Bailey's says that it is metal from the softer piston that has marked the jug and that the acid will clean it off.
I will say it again in this thread, I agree with others here. Something else is the problem unless you forgot the mix entirely. 50:1 is fine, you've run saws for along time was it running super lean? What did the plug look like? Easily a problem like Brian was mentioning could've happened when the rebuild went down.
I have used acid and yes it works but even after that I wet sand with wd-40.
Do the plug check, It does sound like a lean condition. A host of things can cause this condition right down to your crank seals. How old is the saw ?
Ditto on what the Skwerl said. Something is definately wrong here.

If you can get by with just sandpaper and work your way down in grit is the way I would go and forget the acid. That stuff can be too corrisive. Can't get in trouble just using sandpaper.

Depends on the clip holding the piston. Most of the time a very small fine tipped screwdriver will get the job done. But I have also used a a small pair of needle nosed pliers, and sometimes an ice pick.

Is this one of Bailey's Big Bore kits by chance ???? I have a 46 due up for a case splitting with new bearings. I was thinking about getting one of those kits for it.
As a rule 600 grit wet or dry paper will not hurt a silicon nickle plated cylinder,the danged stuff is very hard.If you are in doubt use a 3M pad.You can get them at the grocery store.A little WD-40 or kerosine should be used in conjuction with it. A soft piston is not the cause.

I agree with others,that saw is sucking air, the boot or clutch side seal more than likely.

The up side is,you are getting a lot of experience in working on saws,it's not a total loss.:)
I use the acid thing all the time, but this only works to remove excess metal and will do nothing for scratches. You have inspected the manifold and found it to be in good shape, right? Then I would suspect you have a crank seal leaking. Once you have the saw back together you need to pressure test it. This should show any air leaks.
See Ya
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  • #13
Cool. I will give it a pressure test before I ever turn it over. I just have to figure out who can do that here.
You might see if the local shop can do it for you, if not you will have to get some specialty tools. Such as a cylinder leak tester, this way you can control the air pressure. Block off rubbers or plates for the intake and exhaust ports. Oh and when you go to put the cylinder on be sure to coat the inside with 2 stroke oil. You need any more help with this Darin just let me know, I help you all I can.
See Ya
You can use a bloodpressure cuff for a tester,works well.If a person were carefull you can also use low pressure air from a compressor. If I recall correctly you should use less than 10 psi. I would really have to look it up as it has been some time since I did a pressure test.

A gauge I believe is the preferred method but soap suds should work in a pinch.

We used to check for air leaks on car engines by squirting starting fluid where the leak was presumed.If there was a leak the engine would speed up a tad.I have no idea if this would work on a small engine.
That don't work so well on saws just because you can't get to all the seals (while it's running). Your right Al don't go over 10psi or you can blow the seals out, or rupture the intake boot. One trick I learned is to turn the saw from side to side, stand it on it's nose, turn it upside down, if you have a leak the saw will change RPMs. The pressure test is the only way to isolate the leak.
See ya
On the only 2cyl jug I've cleaned, I used oven cleaner, heat, and a flap wheel in a drill.

Worked dandy like, and didn't require much effort.
Oven cleaner, never heard of that, I'll have to give it a try thanks Carl. I have a 660 jug I'm acid cleaning now.
Oven cleaner, never heard of that, I'll have to give it a try thanks Carl. I have a 660 jug I'm acid cleaning now.

I think you just made history!

I heated the jug up on a propane burner (aka grill) squirted oven cleaner in it then assaulted it with the flap wheel.

The history part is you didn't sign off with "see ya, Mike".

Strangely, the world hasn't stopped spinning... hmm
Damn I can't let that happen, I better realign the planets. Is this better?:D
See Ya
I have no idea what is in oven cleaner,nasty stuff I suppose.It works well to remove pine pitch from circular saw blades.It must have some ammonia in it because it smells like Tom cat pee.Yuck,almost as bad as Stinky the feret.
I know I have used oven cleaner to prep engine blocks, without heat even!!! DO NOT use that stuff if you want to save the paint!!!
Saved another one, the 660 jug cleaned up good, now I just need a piston, instead of a piston & cylinder. $108.80 vs $294.99, saved the customer a good chunk of dough.
See Ya