After 30 years, even Honda engines may need overhauling. The 350 and 400 fours, are perhaps the hardest worked engines of all the SOHC air-cooled 'Fours'. Without a doubt the valve gear, with the rev hungry nature of these engines has a tough time, so when the inevitable overhaul is required, why not fit new rocker arms, and remove any niggling doubts of potential catastrophic failures when revving hard through the gears!
