Motorcycle Repair: compression pressure problem, blown head gasket, piston rings

Question
Hi, i know that you are expert in older bikes, but i have a problem with a '00 Yamaha R6. I hope you can help me.

for my bike, it will not idle as it will just simply die off after a while. I have to keep the trottle on to keep the engine running. i got it checked, and found out that the compression pressure in each cylinder is way below the min requirement. i dont know what causes it, hoping you can help me with this? can you name me things that will cause this problem?

i really appericate your help

Answer
Hi,
insufficient valve clearance can lower your compression.
Also, stuck or worn piston rings and/or leaking intake or exhaust valves. Possibly a blown head gasket, but this is more common to one cylinder being low.
Usually dirty carb jets or lack of fuel prevents idle,
but if you are sure the compression is very low
check the valve clearance first. I don't have the
specs handy, but they should be available on the "net"
You may need to replace the compression/oil rings
and grind the valves if setting the valve clearance
doesn't help.