there's no absolute guideline on how many kms an engine has to be rebuilt.. depends on the care of the engine lah.. mileage does give somewhat clues on when an engine needs to be rebuilt, but if u really take care of it in terms of maintenance n not trashing it too much it will last a long time..
from whut i know, the rotary needs the apex seals to be replaced.. search the net, or mebbe sifu can answer
from whut i know, the rotary needs the apex seals to be replaced.. search the net, or mebbe sifu can answer