OX66 question

[nickmo12]

Hi, I've owned a 1999 Regulator since new with 225 OX66s. I've done all my own maintenance including cleaning the VST filter. I've cleaned them so many times (they were always clean) I thought it might be time to replace them. When I received the parts, they looked different, but heard they had been redesigned. The filters would not fit which is when I discovered I have 1998 motors. I got the right filters and replaced them.
My question is- why did Yamaha make the new design smaller? It seems like the old design had a lot more filtering area.

[rodbolt17]

cause there are two designs of the ox-66 225.
depends on year and shaft length.
one uses a 66k the other a 65l.
the two do not interchange.
use better care looking up parts..

[nickmo12]

Understood. The part for the older motor has more filtering surface than the newer filter. Just wondering why the design was changed.

[fairdeal]

Rodbolt is a national treasure - a priceless font of practical Yamaha knowledge.
He seems to concentrate on what he needs to know to fix broken engines, not on "curiosity".

Some of us non-professionals here enjoy wondering why design decisions were made,
such as the two VST filters you mention.





Here's a more baffling example:
despite having already, in use, those filters,
when Yamaha introduced the F115 in 2000,
they used instead this tiny screen for the VST:



and then continued to use it for the F225

[99yam40]

white one looks like it would suck any trash off the very bottom on the VST, the blue one with the side screens does not look like it is open on the bottom so it would not suck the trash off of the very bottom. but might suck air if the level dropped down a little to far.

now the black one, I am not sure what the bottom looks like or the sides as far as pick up openings and if it will suck anything off the bottom or not.
maybe it will not so they reduced the size of the screen

[nickmo12]

Thanks Fairdeal and Rodbolt. 99Yam40 that's what I thought too. I have the blue one. It seems like a better filter. Don't know why they changed to what looks like a filter with a smaller filtering area. BTW the blue one has a screen on the bottom too.

[pstephens46]

Yamaha does not explain changes.