exhaust maintenance

[MichaelTorre]

I have a 250 with 12000 miles and its never been decarboned.
On a side note it has been sitting silent since 1984.

I am interested in cleaning the silencer rather than waiting for it to plug.

What's this caustic soda you folks refer to ? Is it Lye ?
And what strength do you use ?
Thanks
Michael
In flat and straight Missoura.

[therealche]

Yup caustic soda = lye = NaOH. Don't know how you buy it in the US but here we buy it in crystal form. The usual way is to plug the end of the silencer with a potato, pour a pound of cuastic down the other end, then very carefully pour some water into the silence... then run like hell! because caustic + water creates a lot of heat and can actually make the water boil.

However with only 12000 miles I wouldn't bother. and with the low ash oils used at lower ratios today they don't block up like they did when they ran on 25:1 with engine oil!. Best way to keep the silencer unblocked is to take the bike out for a nice long run as fast as you can!

[MichaelTorre]

Hmmm .
Unknown history of how it was run and the oil used before 1983.
Cylinder is within .0004 concentricity, but that shows the care that the Germans put in it.

Old evidence of slight seizure and scuffing on one corner. Most likely I harsh break in.
Some Yanks feel that a break in must happen in one afternoon. I noticed that most of
them drive rat-bat jolopies. I digress.

Point is the muffler feels heavy. Is that normal ?
It would be very good if it doesn't have
5 lbs of soot in it.

[therealche]

The mufflers are quite heavy even when new, theres an awful lot of metal in them.

[Guesi]

I have never in my life cleaned ,an MZ exhaust,and I drove more than 12 000 miles on MZ.
So it is simply not necessary....

[MichaelTorre]

that is very much a relief to hear that the exhaust is natuarly heavy , and an MZ owner that I know
drives a lot, doesn't reports he doesnt need to de-carbon.

I have problems getting up the courage to pour chemicals in a closed tube and then running for my life because of the chemical reactions that's going to happen.

My concern started when I remembered have seen quite a bit of people pour some really nasty stuff in thier gas tanks in the name of two stroke economy!

M

[therealche]

Just give it a damn good thrashing now and again, gets the carbon nice and hot,burn the oil off and cleat the tubes out. Clogged exhausts in my experience are found on bikes that have spent their lives doing a couple of miles to the shops with a rider who always sticks a bit of extra oil in the tank, "just to be on the safe side"

[den]

what are you thinking of , there are two things on topic here,,are we talking about a CARBON build up or the thick OILY STICKY MESS build up,
I remember i've done it in the past is the caustic soda route,,worked quite well,,no dangers, no smells,, just wear goggles and away you go ,
as for the gluey sticky oil .. i just soaked it in petrol for a day and poured the diluted gunk out,,I would think if the exhaust got too clogged up it would just make the bike noisier,Take it off and blow through it , it should NOT be restrictive,,Just give it a go , it will not do any damage,,

[MichaelTorre]

to be clear I was talking about the dry carbon, I was concerned about.

That is a good idea cleaning the gooey mess with petrol which I don't have
but seen it on othe bikes.

thank you
Michael

[MichaelTorre]

oh no. I looked in the header pipe and what did I see,
but a gooey, gooey mess.
Deposit is from using the wrong oil ,
or to much oil ,or both.
Please pass the acetone !
M

[Guesi]

Simply take a longer ride with high revs and all the mess is gone....
I prefer to take this ride in the night, so you feel like a rocket with all these glowing sparks coming out of the exhaust
And 1 : 50 mixture is enough.
Not always the word is right: the more the better

[Cerberus73]

i done the exhaust on my ETZ 250 the other day.. i did have caustic soda, but since the bike has only done under 10k miles from new.. i figured id get off with just a gentler clean.. i used brake cleaner and petrol mix.. potato in end.. poured in a couple of litres of the concoction, and blocked up the other end. swilled the mix around for a few hours.. unplugged the end, and poured out the resultant sludge.. it was a bit thick, and gloopy.. stuck in another mix of the brake cleaner and petrol. and swilled it for another 30 min. the mix came out a little dirty but not thick, so i figured it had cleared most of it out. done same to the header pipe and pushed through a stainless pot scourer to clean up the carbon film. i left it overnight to dry out properly. and refitted exhaust to the bike.