Two cycle/ stroke exhaust port cleaning technique.

[rogerf]

Hallo folks,

After ten years I've decided it's time to clean the exhaust port on my Talon AT3338S line trimmer, before carbon build up causes a problem. This brand has disappeared from sale for about 5/6 years here, and I don't believe it was ever available in the USA.

I've googled the process and it seems some recommend blocking the exhaust port with the piston skirt to avoid getting carbon into the bore, whilst others (including the author Paul Dempsey) suggest lowering the piston crown below the port, blowing the carbon out of the combustion chamber by rapidly spinning the engine.

I'm planning on using a soft scraper (plastic or copper) and maybe some carb cleaner to soften the carbon if necessary.

What is the best method/piston position? Does it matter?

Looking forward to some good advice.

Cheers, Roger

[bgsengine]

Block the port with piston skit - The other way suggested, if you get any sort of carbon sticking out or sticking to the crown , soon as that carbon wedges between piston crown and exhaust port, you're gonna have damage that will result in a blown engine sooner or later.

With the piston skirt blocking port, there's not gonna be anything sticking out to catch on piston or port - once cleaning is done, take a soft shop towel , twist a corner to make a swab, dip it in a bit of 2-stroke oil and use that to "pick up" any remaining bits of carbon and you should be good to go.

[rogerf]

Thank you bgsengine

That is very clear and concise, I'll follow your suggestions and the excellent tip to use the corner of a shop towel with two stroke oil to pick up any escaping bits of carbon.

Thanks again for you fast and clear instructions. I'll get back when it's all done & running again.

Cheers, Roger

[Deere2me]

Here's what I do, been doin' it this way for years with NO problems or comebacks:
Lower the piston completely, remove the sparkplug and insert air blowgun in. I use a fitting and quarter turn valve, but a blowgun will absolutely work.
I use a narrow pointed steak knife to scrape the deposits out while keeping a steady stream of air to blast the chips out. Usually keeping the port facing down. No chance of carbon getting stuck in the cylinder/piston. I tend to drag the tool to the outside while scraping. I also use a small round file, using the same dragging outside motion.
I finish with a shot of air thru the plug hole using my blowgun with a long, skinny tube type snout. You could also use a piece of fuel line on your gun if you don't have one.

[StarTech]

All's well but I would go ahead and check that piston skirt for damage already done by the carbon buildup inside edge of that exhaust port since the port is open to see it. The unit may already be due for piston and ring replacement plus depending on the cylinder type the cylinder itself. Just a heads up note.

[rogerf]

Thanks everyone for your practical advice

Job now done without any dramas. I used the skirt across port technique as suggested by bgsengine, but I do like Deere2me's idea and WILL make up that fitting before the next time. Shouldn't be too hard, a bit of 3/4" hex bar turned down and threaded 14mmx 1.25 to fit the plug hole, and the other end tapped to take a Nitto fitting.

Thank you for your suggestion Starfire1, I did check the entire length of the piston skirt for damage, there was very little which was only surface marking over a short distance (1/2" or so). I don't think that will lead to a problem any time soon.

I was a bit surprised to find that this old and originally inexpensive machine does have a chromed cylinder and the piston is fitted with two rings both of which did move a bit when prodded with a plastic handle (only expected one ring on a cheap machine). However the two M5 x 0.8mm exhaust muffler bolts were almost loose when I took them out - not much more than just snug. I tightened them down to 50 in lbs when I finished as it seems to be about the mid range of the torque settings for this sized bolt in the situation that I can find online. (Haven't had any luck looking for Talon workshop manuals on line although I believe the finished up being swallowed by Husqvarna.

I was also surprised by how little carbon build up there was after 10 years of use, just a thin film under the oil. It came off easily with carby cleaner on cotton wool bud. The two stroke oil I've been using must be good!

Thanks again for all the practical advice.

Cheers, Roger

[wristpin]

No one has mentioned the possibility of a coked muffler. If it's steel I always give them a good cook with a blow lamp . Aluminium mufflers don't take kindly to this treatment though! I give them a good soak in a carbon removing product sold to the commercial catering trade for cleaning stoves etc.

[rogerf]

Hallo wristpin,

Thanks for your input . Maybe I should have cleaned out the muffler which is steel, but the machine runs fine and I just wanted to be sure that there wasn't any carbon about to cause damage after a longish period of use.

I had thought of using some lye if necessary, but the engine runs & accelerates well as it is. The exhaust also has a good 'pop' sound and doesn't sound clogged.

Speaking of a solution of lye (sodium hydroxide) which can be bought here as a drain cleaning product in the supermarket, ( might be the same as your carbon cleaning product but with a different label on the jar) does anyone have any suggestions for the mixture to use for muffler cleaning?

Cheers, Roger.