Besides regular mechanical maintenance, treat your motor to low humidity storage, good fuel run through a filter and shade. The metal parts may not care about sun exposure but the harness sure does.
Ours have ridden behind the Enterprise for years and show why it’s a hard life. Rust and corrosion never wander far.
Interestingly, the occasional fuel spill doesn’t do that much to Nylon based harnesses but, apparently, high humidity causes degradation over time although nowhere near as much as sunlight.