Never heard of electronic start. Maybe you are thinking of electric start.
Go the Yamaha USA website. Open the parts book for the F25MLHB model and then for the F25ELHB model. Compare the parts differences. Remove the parts that are used on the F25MLHB that are not used on the F25ELHB and then add the parts that are used on the F25ELHB that are not used on the F25MLHB.
One boat unit might cover it. If you do the work yourself.
