I was mounting my new larger rear sprocket and disassembled for the first time ever my jackshaft assembly because I wanted to see what needed replacing to eliminate the sugstantial wobble of the large jackshaft sprocket. IT turns out that the factory design is deficient in my mind because of the sloppy fit of the sprocket on the jackshaft and resultant wobble but this mb-165 from the looks of it has had a terribly rough and long life and if the jackshaft design held up this long then maybe I am wrong and
the proof is the long time performance instead of my ideas about slop and wobble of a sprocket on a shaft. In any case, with all the wobble the keys in the grooves in the jackshaft were nearly rounded and they need to be replaced. My trusty micrometer led me to believe that these keys are 5mm x 5mm and boy are they hard to find !
Visited all local auto parts stores, all local lawn repair shops, all local True Value and Ace hardware stores. Finally found 5mm x 5mm keys at McMaster Carr, Grainger and
Fastenal industrial distributors..... I think I have finally seen why the original factory tranny setups cannot last forever. But they sure might last a long time.... Arguably as long or longer than the rest of the bike will hold up. So I guess it might be good design optimization.
If you have one of these older mini bikes definitely DO NOT LOSE these keys.
I guess the writing is on the wall that I will inevitably switch to a Torque Converter when the current systems grenades !
the proof is the long time performance instead of my ideas about slop and wobble of a sprocket on a shaft. In any case, with all the wobble the keys in the grooves in the jackshaft were nearly rounded and they need to be replaced. My trusty micrometer led me to believe that these keys are 5mm x 5mm and boy are they hard to find !
Visited all local auto parts stores, all local lawn repair shops, all local True Value and Ace hardware stores. Finally found 5mm x 5mm keys at McMaster Carr, Grainger and
Fastenal industrial distributors..... I think I have finally seen why the original factory tranny setups cannot last forever. But they sure might last a long time.... Arguably as long or longer than the rest of the bike will hold up. So I guess it might be good design optimization.
If you have one of these older mini bikes definitely DO NOT LOSE these keys.
I guess the writing is on the wall that I will inevitably switch to a Torque Converter when the current systems grenades !