With air cooled engines, the expansion and contraction in the run/stop cycle is much greater than in a liquid cooled engine.
My experience with A/C engines ranges from VWs to lawnmowers. With VWs, adjust valve every oil change, and use straight weight 30 oil. No ifs, ands, or buts.
It could not hurt to CHECK the valves. Then if they need adjustment, you could bring the valves into spec regardless of mfgr guidelines.
Adjusting valves [if there is a fairly simple lock nut/bolt] is fairly simple. So, why not adjust valves, regardless of mfgr recommendations?
Also, with the leaning of the mix [for emissions] the cooling capacity of the engine to coolitself is diminished. So shortened CHECK intervals would not be out of line.
We used to rely on rich A/F mix to help cool engine. Can't afford that now.
Last edited by yankdownunder; 12-27-2013 at 11:09 PM.