  Recently, Takayasu and Tretyakov [Phys. Rev. Lett. {\bf 68}, 3060 (1992)],
studied branching annihilating random walks (BAW) with $n=1$-5 offspring. These
models exhibit a continuous phase transition to an absorbing state. For odd $n$
the models belong to the universality class of directed percolation. For even
$n$ the particle number is conserved modulo 2 and the critical behavior is not
compatible with directed percolation. In this article I study the BAW with
$n=4$ using time-dependent simulations and finite-size scaling obtaining
precise estimates for various critical exponents. The results are consistent
with the conjecture: $\beta/\nuh = {1/2}$, $\nuv/\nuh = {7/4}$, $\gamma = 0$,
$\delta = {2/7}$, $\eta = 0$, $z = {8/7}$, and $\delta_{h} = {9/2}$.
