How to clean expansion chamber?

[blinkerfluid]

I have a pro circuit platinum expansion chamber on my 98 kx250 and it has been on the bike for quite some time. I noticed the front flange sits in the head crooked, at a decent angle so one side of the copper gasket gets smashed flat and the other is lightly squished.. not sure what causes that.

The other problem im having, is there is alot of carbon build up inside the expansion chamber. Ive heard excess buildup can cause performance loss.
Anyone know how i can get the carbon out? Its pretty thick in there, about 100 thou.

Ive heard campfire in redhot coals and it will just fall out, but all that heat will discolor the chrome plating..

[Foxx4Beaver]

It's obviously taken a hit and got tweaked bad enough to wear out your copper gasket awkwardly and prematurely,and if it's doing that,then it's almost gauranteed to be wearing out your cylinder flange as well.If it were me...I'd say save the aggravation of cleaning something that's already got other issues,and is only gonna cause more problems down the road,and just spend the $200 or so and buy a new one....then it's bolt-on and go,aggravation free!

[81cr450]

When i built my af I had to twist & tweak to get my pipe to fit. You can undo all the mounting points, except the springs, with a long pipe in the stinger just tweak it back to where it should be. if it sits good unbolted you r good. At the shop we have an oven for burning carbon buildup off of heads before we rebuild them. 550* for about 5hrs takes the heavy stuff off. I dont know if it would discolor the plating but it would be alot more controlled than a fire. Then there is the spray cabinet, caustic dishwasher that it could be run through after to rinse it out. I'd guess most machine shops would have this equipment. probably $30 bucks to do

[serafin]

Get yourself a piece of wire rope (steel cable) unbraid the end and attach it to your drill and insert the end into the pipe and drill away.  It works like a wire wheel.  I've used this technique before with good results.

serafin

[Rhyno]

Since I am not at WOT much, my pipe doesn't the retain heat, so I wrapped my pipe with "Header Wrap."  It is a little tougher to get a good tight wrap on the ever changing diameter, but I did it with "patience" and some water.  Then, I used Stainless Steel Tye wire and did some double wraps every three inches, or so.  It covers from the rubber O-Ring to a couple of inches past the back of the cone.  (It hasn't came undone or moved, either.....)

It works for me, and silences it, a little bit.

The first few rides after install, there were chunks of carbon hung up in my homemade-spark arrestor. 

WOT, vibration and heat, and they were gone.

-Rhyno

[RoostDaddy]

if you want it done right send it out and have it straightened and de-carboned.   if you want to do it yourself, heat the inside of the header part with a small propane torch and scrape the carbon with a flat screwdriver. Once you knock out the big pieces, you can use a wire wheel on a drill and knock off the rest.  As for straightening it, heat the neck and use a bar to pull it where you need it.  Fairly simple if its not tweaked too bad.  Most pipe repair companies charge around $50 should you go that route.

[blinkerfluid]

it bolts up to the mounting points fine and sits in the cylinder fine, but the actual flange inside the cylinder sits at a good angle.. theres 2 grooves inside the port from the orings, but they are all the way around the port.

i know how to weld so i was thinking worst case cut the flange off near the head, get it in the head straight, and then weld it back on.

im not trying to spend too much money, as im not a pro, just a hobby rider.. and im thinking of moving this summer and chances are i wont be able to take it with and would be selling it.

[Larry Wiechman]

 Find a local diesel or automotive engine shop that still has a hot tank cleaning system. The EPA has forced most of them out of existence, but some are still around and they are magic.

[blinkerfluid]

i ended up heating it up with a blowtorch and tweaked it back, so now it sits in there straighter, not 100% perfect. it still has a slight angle but barely noticeable. the next problem, is the previous owner for the bottom bracket just used a peice of aluminum to bolt the pipe to the frame, and over a few rides it would crack. i welded it up before and it cracked on the one side.  i ended up welding it back up, and after straightening up the pipe, that lower bracket is now 3/4 inch from the frame.

i ended up taking 2 rubber grommets for wiring, and putting that behind the bracket and then bolting it to the frame. so now the bottom bracket has some rubber dampening along with the top stock mount.. shouldnt crack from vibrations anymore.

while having the pipe off i noticed im going to need to do a top end in the future

[Twosmokerfan]

This is what I did with my 500 Pro Circuit and previous pipes (of course i wasn't too worried about the platinum finish)

I got my gas fired blow torch and a compressor at full pressure ready to go with a air nozzle hand piece connected with a cable tie to hold the trigger on.

Heat up the header part that connects to engine until the carbon is cherry red, then take the air compressor hand piece and start blowing air into the header in the same direction as the exhaust would flow.  If you have a high delivery CFM compressor, this helps, but a 40 cfm will do (albiet slow).

The carbon will burn in a ring all the way through the exhaust until it runs out of carbon and oil build up.  Wait until it cools, and tap with wooden mallet, and the loose carbon falls out.

It gets pretty hot, and make sure you do it at a friends farm, or else the whole neighborhood gets a load of burning oil.  Also, keep the pipe supported with the tail part pointing straight up, and it turns out a bit like a chimney.  (just don't breathe it in)  That said, the EPA may have something to say about all the smoke.  It works faster with straight Oxygen from an oxy acetylene set, but it also heats up the pipe a lot.  One tip though, when you start, don't stop until it completely burns out, as it is a problem to get the carbon hot enough again when it is half way down the pipe.

In the end, it actually didn't damage the pro circuit finish that couldn't be polished out.

Can't really help you with the bend.