Motorcycle Repair: electrical, crank shaft, combustion chambers

Question
hello

i have a problem with a 2001 yamaha raptor 660r i rebuild the the engine from the crank shaft up new push rod and bearing piston and rings .
when the engine is cold and i crank the engine for about 15 minutes and when the exhust pipe on the bike heats up to an untouchable tempurture the bike will start and run perfect but if i let it cool down for about 3 hours same problem again i have cleaned and jetted the carbs changed the egnition coil checked the timing
now i am all out of ideas . any help you have will be greatly appriciated
                      thanks in advance
                        chris kazalas
                   KAZALAS@AOL.COM
                         1/5/06  

Answer
Hi Chris,

Perform a cylinder compression check and leak-down test to learn the sealing properties of the combustion chambers (condition of the engine).

Check valve clearances. Valve clearances and cylinder compression must be within service limits before the carburetor will work properly.

Electronic ignition timing is pre-set and non-adjustable.

Why was carburetor jetting changed?

Learn to read the appearance of the spark plugs to know what changes to make to the air-fuel mixtures (jetting). Visit NGK's website to learn more about reading plugs.

www.ngk.com/sparkplug411.asp

I'll send tech files to your email address.

Respectfully,
Mark Shively