I've probably showed you this build up in my 100 twin header pipe. 

Hot Pipes Roasting on an Open Fire.

Two JT pipes in there. The were noticeably lighter after their stint in the fire.

 

@RT325, man... that's pretty bad... no let me correct that... that's really bad.
About how loud it is, yes maybe a little.

@Schu, I could do that. My chamber might even be cleaner since it may pop some of the rust off the outside...

Well I took RT325s advice and cooked the expansion chamber ala Schu (thanks for the idea}. A little bit of flakes came out after an hour or so in the coals. The first pic below is the fire just getting started. Good Doug Fir wood kicks... gets hotter'n a banshee. What little paint was on the pipe turned white. I thought the extreme heat would pop the rust off to make it good timing to paint the pipe, but I was mistaken. The pipe was still quite rusty and it would take a millennia to clean by wire brush.  One thing I do know now, is that it's clean on the inside.

Question, would Evapo-rust clean it off the outside if I wrapped it in plastic to contain the cleaner and shifted it around time after time to hopefully get all sides cleaned? I have it handy now, since I blew up the original gas tank that needed it on, and the replacement tank is clean already, it's kinda just setting around.

   

Another thing I did he suggested was to advance the timing to 2.3mm. I for some reason thought the factory recommended was 2.0mm, that's why I did that, of course I don't know where I seen it. Well that really made a difference. First ride it really ripped! Just riding it around on my lawn in the grass, shifting from 1st to 2nd, pulled the front wheel up. Well I thought, I need a place to ride this thing now since it is running so good. Actually that was the second thought after the wheel went up... the first thought was I could hurt myself with this thing if I am not careful. I only rode it for a few minutes, enough to see the change. It appears the missing at higher RPM went away too. I could be wrong, but it is definately a step in the right direction.

Now to find a place to ride tat isn't an hour away...

Yeah they don’t come out of the fire ready for paint. I sandblast mine, but it finds any thin spots. Luckily the pin holes were fixable.
 

Man alive!
There's no point messing about with a blow torch.
That's a proper fire.
I like it.

It has been a while, and finally got to ride the MX on a trail I just found out about that was close by. This may be the last post on this string since it is kinda a "full circle" thing, from tore up, dry rotted tires with a mouse nest in the air filter and lower end. Oh, and setting for 35 plus years, it waiting for me to stop wishing I could get it going again to actually getting it going. Life does get in the way sometimes...

First big ride

Someone mention mouse nest or exhaust burn out.Someone mention mouse nest or exhaust burn out.   

Well done Mr. Hackman! Now to wash it up and put many more hours of riding it!
Sneezles61

Congratulations!  Great accomplishment and I'm sure a great thrill after all these years.