Originally Posted by SrTelemaster
Keep in mind that a pushrod housed in an external tube like an OS 4-stroke or Harley Davidson "V" twin will not get as hot as the cylinder/head that is containing hot combustion gases. (or pushrods housed internally)
Even when running aluminum pushrods (W/a higher expansion factor) W/cast iron cylinders in the old pre-Evolution Harley Davidson engines, valve lash, when using solid lifters, was esentially set to .000" when cold. This was accomplished by setting the lash adjustment so that the pushrods would spin W/slight drag between the fingers.
As long as there was .000" or more lash when cold, the differing expansion of the hotter cylinder/head compared tom the pushrods, would increase lash over the cold settings. Minimal lash settings are to asssure complete closing of the valves until opertaing temperture is normalized.
Modern hydraulic lifters keep lash @ .000" throughout the temperture envelope.
I am not a harley mechanic, nor a harley enthousiast (In my humble opinion, those engines are very strange and illogic contraptions) but that would be the first time that I hear from an engine that needs to have 0 lash when cold. Could have something to do with the abnormal pushrod length though.
Anyway, virtually all other engines need a positive valve clearance.
But that is not the point, what harleys need or not need.
My valve clearance is OK, of that I am sure.
My valves are not leaking, but my OS is running slightly hot....
It keeps running OK, did another 30 miutes this afternoon before the cold drove me back home.
I am getting the impression that the 15% oil is slightly too much, but I am not sure if I want to change it.... it is kinda convenient to have the same fuel for all engines (gassers excepted), but I think I will at least go to 0 Nitro, as the two-strokes don't need it, and it will facilitate leaning out a bit more, reducing the oil sloshing around in the fourstroke a little bit.
Now for to improve cooling.
Anyone knows a decent way to get some extra cooling fins on a fourstroke? Not easy to get a heatsink on them like on a 2 stroker.