Mainshaft O ring

[bamacl]

Reading through the resto and engine manuals I noticed where it says to install o ring in end of mainshaft. So I look at the parts break down to see where it is and yes shown as #4 item. Reread of the Honda shop manual and no mention of o ring is made. It is almost hidden by the bearing and no name or number is given in that break down. The only thing I can think it's for is to help seal between the clutch lifter and mainshaft when the clutch is engauged. Less loss of oil for trans lube? When you disengauge the clutch the lifter will move as will the o ring. So is it really needed?

[48lesco]

I would suggest including it. It would seem from the lubrication schematic that oil pressure would depend on it. All of the 305 parts diagrams show it as part number 91305-259-000. That part number supercedes to 91303-634-010 (available from Honda).

[Hoosier Tom]

...the lifter will move as will the o ring. So is it really needed?

The o-ring will not move. There is a machined groove it fits in. As Chuck noted you should keep it in the system.

HT

[Farm Shop]

Does anyone have a picture of where this o ring goes?

I am in the middle of doing a scrambler motor and I didn't find any o ring on the main shaft?

And it wouldn't be the first thing the last person that had this apart screwed up........

Fs

[Hoosier Tom]

It's the left end of the main shaft where the clutch slides on. See my pic at the following link. If you look closely you can see the o-ring inside the shaft. http://www.honda305.com/forums/download.php?id=5573

HT

[Farm Shop]

Perfect thank you!!

Mine is most certainly missing......

[bamacl]

Thanks for the reply. Just what I thought. When I rebuilt the engine I did not remove it. Of course that does' t mean it's there. Time to order a new gasket and make sure.