Two Stroke Motocross

Two Stroke Motocross Forum => Technical => Topic started by: Rota Ash on March 13, 2010, 02:25:04 PM

Title: de carbonising expansion chamber
Post by: Rota Ash on March 13, 2010, 02:25:04 PM
looking in my expansion chamber the other day its full f carbon,  the previous owner had been runnig a rich oil mixture as well as the bike being very rich in the air/fuel ratio, whats the easiest way of getting the built up carbon out without cutting the pipe apart, its an fmf gnarly pipe in good nic besides the fact its full of carbon, is there any product that basically just eats carbon away ?
Title: Re: de carbonising expansion chamber
Post by: Chokey on March 13, 2010, 08:08:22 PM
I take my pipes to the local radiator shop and have them hot-tanked. They come out like new, and it usually only costs $10-15.
Title: Re: de carbonising expansion chamber
Post by: Rota Ash on March 21, 2010, 03:47:39 PM
ended up takin them in to an engine building shop cost me $10 defo worth it!!! came out like brand new
Title: Re: de carbonising expansion chamber
Post by: DangisMX on March 27, 2010, 05:48:05 AM
Hey everybody, this is my first post here, although i have been hanging around for some time now:)

This may sound stupid, but I my granddad said he would simply hang pipes over a fire and it would burn away everything from the inside. This is pretty old school, and he did it with straight pipes from old russian two stroke motorcycles, so it's hard to tell how it would work with a pipe that's not straight...And you would end up with a really dirty piece of metal that still would need to be cleaned :) . Just thought that this is something cool that I can share and finally make my first post here :)
Title: Re: de carbonising expansion chamber
Post by: ford832 on March 27, 2010, 03:07:22 PM
Not a bad idea at all.I just take an oxyacetylene torch to mine,of course it needs to be painted afterwards.
Title: Re: de carbonising expansion chamber
Post by: Chokey on March 27, 2010, 04:05:13 PM
That will work, if you don't mind having to re-finish the pipe afterwards.

The hot tank won't harm the finish at all, and will clean the inside much more thoroughly.
Title: Re: de carbonising expansion chamber
Post by: ford832 on April 01, 2010, 03:50:24 PM
The amount of rock dings and smashes in mine make the refinishing issue irrelevant.I really need to invest in a pipe guard ;D
Title: Re: de carbonising expansion chamber
Post by: Chokey on April 01, 2010, 06:20:30 PM
The amount of rock dings and smashes in mine make the refinishing issue irrelevant.I really need to invest in a pipe guard ;D
And send the pipe to www.piperepair.com (http://www.piperepair.com)
Title: Re: de carbonising expansion chamber
Post by: maicoman009 on May 06, 2010, 12:10:49 PM
Rota Ash I'm glad you got your FMF "gnarly" pipe cleaned out.Now that it's nice & clean again you can do what I like to do to keep it carbon free & clean.Take the beast out to the longest dirt strait you can find & run the piss out of it!!! I mean REALLY wined it out in every gear wide open till it can't rev any further & do that in every gear until you run out of road!That will keep it clean plus you'll have lots of fun doing it! :P :o :D >:D
Title: Re: de carbonising expansion chamber
Post by: 2T Institute on May 06, 2010, 02:46:58 PM
looking in my expansion chamber the other day its full f carbon,  the previous owner had been runnig a rich oil mixture as well as the bike being very rich in the air/fuel ratio, whats the easiest way of getting the built up carbon out without cutting the pipe apart, its an fmf gnarly pipe in good nic besides the fact its full of carbon, is there any product that basically just eats carbon away ?

First rich oil mixtures don't cause carbon build up rich JETTING causes it. As combustion temps never get hot enough to burn the oil. I showed a friend a pipe from a kart that I helped tune and after 2 years running and week of the pipe sitting round outside had slight surface rust inside the header.I had a hard time convincing him the pipe had been actualy used.
Ordinary caustic soda (drain cleaner) will when left in the pipe overnight shift 90% of carbon build up, along with a stiff wire with a hook and banging with a mallet.
Title: Re: de carbonising expansion chamber
Post by: ford832 on May 06, 2010, 04:37:31 PM
Rota Ash I'm glad you got your FMF "gnarly" pipe cleaned out.Now that it's nice & clean again you can do what I like to do to keep it carbon free & clean.Take the beast out to the longest dirt strait you can find & run the piss out of it!!! I mean REALLY wined it out in every gear wide open till it can't rev any further & do that in every gear until you run out of road!That will keep it clean plus you'll have lots of fun doing it! :P :o :D >:D

That procedure also has the added benefit of allowing you to perfect your engine rebuilding skills. :o
Title: Re: de carbonising expansion chamber
Post by: Rota Ash on May 08, 2010, 12:35:28 AM
looking in my expansion chamber the other day its full f carbon,  the previous owner had been runnig a rich oil mixture as well as the bike being very rich in the air/fuel ratio, whats the easiest way of getting the built up carbon out without cutting the pipe apart, its an fmf gnarly pipe in good nic besides the fact its full of carbon, is there any product that basically just eats carbon away ?

First rich oil mixtures don't cause carbon build up rich JETTING causes it. As combustion temps never get hot enough to burn the oil. I showed a friend a pipe from a kart that I helped tune and after 2 years running and week of the pipe sitting round outside had slight surface rust inside the header.I had a hard time convincing him the pipe had been actualy used.
Ordinary caustic soda (drain cleaner) will when left in the pipe overnight shift 90% of carbon build up, along with a stiff wire with a hook and banging with a mallet.


yeh my bike is jetted way too rich but im not gonna jet it till i get a new rear silencer, i think that is all i can do performance wise to the bike now everything else has been done  :)
Title: Re: de carbonising expansion chamber
Post by: MyckMcClung on January 07, 2011, 05:11:18 AM
the silencer won't make a bit of differeence in your jetting issue, rejet it now, or you'll be right back where you started, carbon builds fast.
Title: Re: de carbonising expansion chamber
Post by: Coop on January 07, 2011, 08:22:22 AM
the silencer won't make a bit of differeence in your jetting issue, rejet it now, or you'll be right back where you started, carbon builds fast.

That's incorrect, a silencer that has oil soaked packing can cause a rich condition.
Title: Re: de carbonising expansion chamber
Post by: TotalNZ on January 07, 2011, 12:24:38 PM
the silencer won't make a bit of differeence in your jetting issue, rejet it now, or you'll be right back where you started, carbon builds fast.

That's incorrect, a silencer that has oil soaked packing can cause a rich condition.
How?
Title: Re: de carbonising expansion chamber
Post by: opfermanmotors on January 07, 2011, 12:43:48 PM
Machine shop guy once told me that you can use drano with water in the exhaust pipes to clean, but wear gloves cause it gets hot.

Title: Re: de carbonising expansion chamber
Post by: Coop on January 07, 2011, 12:46:02 PM
How?

Eric Gorr told me that once around 2000 when I was having plug fouling issues on a KX250, and he was right. I repacked the silencer and that bike ran great again. Ever since then 2-3 times a year I repack to keep them fresh. I honestly don't remember the "science" of it. Something about acoustic waves and back pressure. It was a long time ago he explained it to me  :D .
Title: Re: de carbonising expansion chamber
Post by: MyckMcClung on January 07, 2011, 06:50:52 PM
What I meant was that a different silencer will not change his jetting settings if he were to rejet before he gets it. He didn't state what silencer he has now, Even the stocker is repackable. costs less than $10 and takes less than an hour. Unless of course the core is as carbon crusted as the Expansion chamber.

Title: Re: de carbonising expansion chamber
Post by: Coop on January 08, 2011, 05:09:18 AM
Gotcha. By the way, welcome to the site. You are a welcome contributor to this tech section. it gets kind of dead in here.
Title: Re: de carbonising expansion chamber
Post by: MyckMcClung on January 15, 2011, 11:39:06 PM
Thanx, glad to be here, been tellin my boys about the site, we hate fourstrokes almost as much as quads
Title: Re: de carbonising expansion chamber
Post by: mj4trax on January 20, 2011, 12:56:25 PM
Thanx, glad to be here, been tellin my boys about the site, we hate fourstrokes almost as much as quads

Hey now. ..   :'(