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Author Topic: M91 water cooled vertical H&M. A recap.  (Read 351 times)


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Re: M91 water cooled vertical H&M. A recap.
« on: May 23, 2021, 05:03:44 am »
 Very nice M-91  H & M operational writeup !!...Your 3 drops MMO per Oz mixture is running at about 200 : 1 gas to lube ratio per gas tank full, No way close to a "typical" conventional 2 stroke gas engine lube mix ratio. And Without any cylinder wall transfer ports or cylinder wall cross-hatch or functional piston oiler, it's Impossible to have any meaningful piston skirt/cylinder wall lubrication (using fuel tank gas/oil mix only) & the typical M-90 engine series teardown inspection usually shows significant scuffing evidence despite the super Hardened stainless steel liner !! ...Obviously, that steel piston IS slapping around the bore with each firing torque "kick" !! I've been consistently directly applying 20 wt oil lube to cylinder wall & entire piston pin underside between engine runs to try to minimize the scuffing effects...With such a beautiful & carefully Machined & precision assembled model engine Without any piston underside oil slinger or piston Oiler provisions or instruction guidance, it's kinda like the Simple longtime utilized full scale engine lube oiller design features  are simply intentionally Ignored ??? ...I can't figure that simple effective important & true to full sale Deletions out ???....just my thoughts,.....tom.


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