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2003 RM 125 - Hard Carbon Build Up in Expansion Chamber

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Hey guys, I noticed that my son's 2003 RM 125 has a good 1/16 to 1/8 inch of hard carbon build up inside his Bill's Pipe Expansion Chamber.

1) What would cause that? Running too rich at one point?

2) How would the carbon build up effect performance?

3) How do I remove the hard carbon build up? Can I fill the pipe with something that would remove the build up?

Thanks

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I think in a similar thread someone mentioned to take it to a radiator shop and have them hot tank it overnite and another suggestion to take it to a auto mechanic and have them put it into a solvent tank. I thought one of those takes paint off but I think the Bill's is stainless steel. I would ask them just to make sure. I think they mentioned that with their experience it cost like 10 or 20 bucks. Let us know how it turns out if you go that route.

I put a buch of oven cleaner inside mine and closed up the openings. It did a marginal job at best. That was also suggested in the post I read.

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no time to find it for you, but I believe there is a method involving simply heating the sh!t out of your pipe - like in some hot coals or on a grill. I might recall something ab soaking it in some solvent? supposedly the carbon inside burns away with a crazy amount of smoke.

This is believable to me because a propane torch was how I ended up cleaning the inside baffle of my silencer. Good Luck

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Burn it, I use a propane torch. It will smoke like crazy so do this out side and be safe. If it turns the plating on the pipe purple, go get some polish that the street biker's use to get the blue off the header pipes. The only other way since it is a Bills and I bet its nickel plated (shinny) is to take it to an auto motor builder who has a heat vat for motors and let him dip it. That may still blue or take the nickel off, but it will be clean. A radiator vat would be good also, so long as they do not use the vat for brass radiators. That is unless you want a gold pipe. Mite be cool?!!

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I ended up trying to burn the carbon out with a propane torch. It smoked a lot and blued the steel (my pipe is not plated at all). A wire wheel should get rid of the blueing with a little work. On the places I could reach I took a screw driver and scraped the carbon ash off but I can't tell how well it worked deep inside the pipe. I'm now soaking the inside with solvent to see if I can't remover anything that's left.

I'm assuming that this could have had a pretty significant negative effect on performance since the inside diameter of the pipe was smaller than designed.....right?

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The best stuff to disolve it out is caustic soda, the pipe will be like new inside after an overnight soak. Just wear lots of protective gear when you're dealing with it.

And yes, a big build up does affect performance, 2 strokes are very sensitive to the shape and thermal properties of the expansion chamber.

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Over here you can get it at hardware shops, I guess similar in the US, though amazon have it too...

http://www.amazon.com/Sodium-Hydroxide-Caustic-Cleaner-Making/dp/B0032LVYXQ

Great stuff, but handle it very carefully. Wear decent protective gear (especially goggles, gloves etc), and add the crystals to water slowly to minimise the reaction (the reaction will cause it to get very hot too). This info may be useful too:

http://www.dow.com/productsafety/finder/caustic.htm

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Ok sounds good. I think I will give it a try. So do you mix some up in a bucket and pour it in and plug the ends or at least one end? Or do you pour some of the powder or crystals into the pipe and add water? How did you guys do it safely?

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I think I'm going to try it also. I'm thinking you would just fill the pipe with some water and pour some of the caustic soda into the water. I'm not sure if you want to plug an end or not......I've seen videos of people making caustic soda bombs with sealed coke bottles! I don't want to make a bomb out of my expansion chamber!

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Mix it in a bucket- add crystals to water, not water to crystals (that is important). Do it a little at a time. And use a plastic bucket, definitely not an aluminium one. Plug one end of the pipe and fill it up, then just watch it heat up and bubble away for a while til you get bored. Leave it overnight, empty it out next day and wash the pipe out with a hose- it'll look better than new inside.

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Thanks a bunch. I will do that. I already got the caustic soda from lowes. I am assuming that it will not eat away at a rubber plug. Well see what happens.

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Well I used this stuff last night and this morning, I poured it all out and rinsed it out with water. I looked inside and it looked exactly like it did before I treated it. So much for the caustic soda trick. The jar said it was 100% and I used about a half of the jar of this stuff for the amount of water that fill the pipe up completly. It did get hot but like I said, it did not seam to do anything at all, at least not in the big end of the pipe, which is as far as I could see. I doubt it was any different inside. There is definatly not any oil or spooge inside there but I thing the oven cleaner I tried last week took that out. But there is definatly that baked in carbon build up inside there. I don't think it's that big of a deal but it would be nice to know how to get it out.

SODA.jpg

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Fire! Build a fire and set the pipe in it. It will smoke pretty good (but yours may not because of already cleaning it) but the carbon will "burn" off the metal. Take a glove and hold the pipe and tap on it with a piece of wood. That will knock all the loose stuff out. I couldn't believe how well it worked when we did my buddys pipe. PS... Be sure your glove doesn't have a hole in it. Bare skin does not handle hot metal very well. Don't ask me how I know!

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I'm really surprised that didn't work, my pipe was spotless after using it, yours must be baked on ultra hard. Sounds like the fire approach is the next thing to try, that's got to sort it out.

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No, sounds like I will leave it alone. I tried the oven cleaner, per someones advise, no good. Then I tried the caustic soda, no good. Now fire? I don't think so. I am not willing to experiment on my shit with someone elses ideas any more. What if fire didn't work? Would some one come up with drop it out of an airplane, maybe that will work. Just kidding, kind of. I don't think it will affect a thing so I will just let it alone. I have a line or two on a replacement pipe and silencer. It that pans out then I might try some more ideas and post back here but thats about it. Their is a pretty good dent in my pipe as it is so later on, I might mess with it.

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Seriously? I deleted it the idea but I don't see that as being anymore dangerous as burning the pipe in a fire or using highly dangerous caustic soda! You could have easily burned your eyes out with sodium hydroxide. Whatever....it worked.

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