1980 yamaha dt 175 runs crappy

[ak jetski]

Thanks for any help in advance,i bought this bike in this condition, im trying to figur out whats wrong with it,it starts really good has good compression but will not rev up it will idle all day long ,but when i twist the throttle ,just a little change in pitch but will not rev up,i put in a new plug,new fuel ,took out the air cleaner,even tride another carb. I thought it had points but it had electronic ignition,so im kinda stumped,thanks kris