SOHC4 exhausts are prone to rusting internally – how can I delay this?
If you get the inside of the pipes cleaned and zinc coated, you will have no rust until the zinc is used up. Sacrificial zinc anodes work well but there's no practical place for them inside the headers. Tankwise, I put some twostroke oil in the fuel, it coats the tank and the inside of the pipes (pipes rusting from the inside is common on these bikes)- never had a problem with plugs fouling etc.....probably because I have a rule which says I only use my SOHC for rides of over 30 mins, so the condense water in the pips gets a chance to burn out. For shorter rides I use my old two stroke. Prepare new pipes by pouring oil into them before mounting, and go for a ride to burn the oil fast to the pipes.