Motorcycle Repair: removing heavy carbon build-up, exhaust ports, chemical compounds

Question
first, thank you for volunteering for this service.
I am working on a 1967 puch (sears allstate) 250 and decided
to de-carbonize the engine and exhaust.  the exhaust ports and
pipes have a thick build up of carbon (1/8 in thick) and i would
like to know how to dissolve or losen up the carbon.  the manual
recomends using a scraper or a screwdriver, my experience tells
me that this method will be difficult at best, further damaging,
denting, scaring at worst. will soaking the offending parts in  
gasoline work or is there another product out there that will do
the job?
                thank you for your consideration on this issue
p.s.  the motor is called a split single

Answer
Hi Mike.

There are a few different chemical compounds that will help dissolve some, if not all of the carbon.  Gasoline is NOT one of them.  Please be aware that none of them are to be used without due care.  Check with a local auto restoration shop to see what they use in that application.
 In addition to that, you may have to get a long rod that you can attach to a drill with a cleaning brush on the end to get down the pipes.  Something in a soft (but not too soft) bristle is best to prevent excessive scoring.

Good luck and ride safe.
FALCON