How to reduce huge gap in ggplot?

My graph looks like this:

Is there any way to reduce the huge gap and set the break myself?

This is a simpler version I am working on:

y1<- c(1,2,1000, 100000) 
x1 <- c (1,2,3,4) 
df <- data.frame(x1,y1) 
graph2 <- ggplot(data = df,aes(x= x1, y= y1)) + geom_point() 
plot(graph2)