Poor starting

[buzzter]

Looking for some troubleshooting tips for a beginner. I've had this MB for about 2 mo. now. Has been running great until the last week. Now it starts very poorly (takes a few runs with pedaling up to 10 mph to get it going). When it does starts it idles very weak and dies at times. If I let the motor warm up for about 5 - 10 minutes it runs better, but not as well as it did a week ago. I've also noticed some loss of power. The only thing I've done so far is replace the plug with a NGK and replace the plug wire but no help.

Any steps or ideas to try next? Thanks

[Norman]

you might try a plug gap of 0.020 is your plug oily and black?if so your too rich need to lean it out.
clean the airfilter if its real oily, wash it in soapy warm water wring it out and install it don't oil it as it will get oily on its own.
you got a inline fuel filter?
if you have run a couple of gallons of fuel ran through it already try a 32 to 1 mix
4oz. of oil to a gallon of regular gas.= 32 to 1
won't hurt to check for intake leaks and for head leaks if you have nasty oily $hiz up on the cylinder fins under your head that is a good bet your head gasket is leaking. oily nasty $hiz by your exhaust port means the exhaust gasket is leaking the leaking exhaust shouldn't hurt you on power.
check your wiring for all connections being tight.
just some of the thing you can try.

[buzzter]

Thanks for the tips. I'll monkey with the mb this weekend and let you know what I find.