no power

[Brian jj]

hi, i have 80 Yamaha 2 stroke.
starts and idles well.
when i open throttle in gear it has no oomph.
doesn't go on the plane, like it's holding back.
carbs have been serviced. new plugs and fuel filter.

[99yam40]

test compression, spark, and timing.

If all is good on them then more than likely you are left with a fuel problem.
Too lean or too rich fuel/air mixture will not let a cylinder to fire properly

[YammyMan]

Could be in "limp" mode due to overheat or bad oil injection sensor. Just something to look at. Good luck