Does anyone know the purpose of the tin inlet port sleeves that fit inside of the aluminum manifolds on my 650SS? The parts book lists them for the "88ss and 650". It seems to me that the sleeves defeat the purpose of the tufnol/phenolic resin heat insulator spacers that separate the manifolds from the head. Wouldn't the sleeves, since they push fit into the head and then line the aluminum manifolds all the way to their carburettor end, work as perfect heat conductors -- as in conducting heat out to the carburettors? What would be the effect of leaving the sleeves out? On the one had they seem to be a form of "polished" port, but on the other they must conduct a lot of heat out towards the carbs. Just thinking about this because my bike ran awfully ragged in the 90+ degree heat we had around here yesterday. Any thoughts appreciated. Marc
#1. "RE: Inlet Port/Manifold Sleeve" In response to Reply # 0
I didnt know these bikes had inserts like this.
If you removed them what would be the diameter of your inlet tracts ?
Im pretty sure that these sleeves are to bring the inlet tract diameter down to improve inlet tract velocities.
I remember reading that the factory had sleeved down the inlet tracts on the Domiracer (which is a close relative of the SS machines). Privateers running similar non factory machines who removed the sleeves supposedly got less performance. The reason they might have shown up on the SS sports machines is that the increased overlap and late inlet closing on the higher performance cams require higher inlet tract velocity to overcome reversion. Removing them may give you poor performance in the lower rpm range.
Dont know about temperature. If you were worried you could make up a thin insulating gasket.