Clutch slipping when i pull out clutch engages but bike dont move very fast and the engine revse high do i need new clutch this is a 89 kx 125

Mechanical issue: clutch not disengaging completely...
engine off - put in gear and roll back and forth with clutch released does engine stop the bike from rolling? Now pull clutch lever in and try rolling again is clutch cable adjusted properly?
Electrical issue: bike thinks clutch is still engaged and kills motor when not in neutral
Is the clutch switch properly connected and working? Is it adjusted properly? Use a multimeter to read resistance across switch contacts does it change state when clutch is pulled in?

Hello
A new clucth will slip a little at first. Its recommended to try to make the clucthes slip.
i just put in a set that instructed me to make the clutches slip.
A brand new set of clutches needs to seat and it will take a few times riding it before it does.

If they continue to slips after a few rides then you should have your master cylinder bled.
If the clutches are not engaging all the way, the clucthes will slip and motor revs but bike dont move.
if the clucthes are not disengaging all the way, the clutches drag, and the bike will edge forward because the clucthes are not disengaing from the motor.

Thats a pretty simple set up, hydraulic just needs to be bled all the way in the same manner you bleed a brake caliper.
once bled there is no adjustment and the clutches should disengage and engage within the first 1/2 inch of pulling in the lever.

Hope that helps, and don't worry about your new clucthes, they will slipp a little but will go away.
i'm sure of it.
Best Regards
Big Al

If the bike hasn't been ridden for a while, select top gear, (engine off) and with the clutch pulled in rock the bike back and forth. That may free the clutch.

the easy way to find out if the cluch is slipping is to ride the bike in top gear pull in the cluch rev the bike up to high revs and drop the cluch if the engine dont drop in revs very fast and the revs only drop slowly its slipping if this happens check that you have a small amount of slack in the cluck cabel ie: 1/4 of an inch is ok if its to tight it will cause the cluch to slip as the engine warms up

u sound smart n thanks for goin oldschool-1st buy a manual-thats how the pros work--in bike yrs its in its 50's-parts wear out-try ajustin cable n then do clutch itself-that does not help-rebuild is probable

push rod bent ? too short ?

possible the cable is needing to be adjusted make sure it is pulling on the pivot

the plates will stick to each other because of oil
check the clutch lever at the motor and make sure it is moving the arm that pushes the pressure plate and make sure it is moving

your clutch is draging adjust the clutch cable so that when you are on the bike with the bike off and in gear and clutch pulled in you can move the bike freely that means the clutch is engaged