This topic has been on my mind for the last few weeks, since I replaced the two stroke oil pump on our Yamaha golf cart. If you followed that posting, you’ll recall that the pump was replaced because it was leaking, not because it wasn’t supplying oil to the engine.
Since the early 1970s – 40 years now – I’ve worked on literally hundreds of Japanese two-stroke engines, virtually all of them with Mikuni oil pumps. In all those years I personally have yet to find one of these oil pumps that actually failed. By the way, my definition of “failed” is the unit stopped pumping oil. Have I had to replace these pumps over the years? Sure, just like my recent golf cart situation. But in my experience not one failed because they stopped pumping oil, but for some other reason such they began leaking.
Now… I’m absolutely sure there’s someone out there that’s experienced an out-right failure of a Mikuni pump… I’ve just never actually met one of these persons face-to-face. Oh I’ve heard the stories of some guy’s brother-in-law’s cousins friend that had an actual pump failure that took out an engine. But I’ve never talked to ’em. So… do I believe it’s possible? Yes, but I believe it’s also very rare.
Over the years, I have a few folks contact me regarding either having me remove their equipment’s oil pump or looking for information about how to do it themselves.
The conversation typically goes something like this:
- Me: Are you having an issue with your oil pump or have reason to believe you have a lubrication issue?
- Caller: “Umm, no, not really, I just want to go to pre-mix”
- Me: “Why?”
- Caller: “I just feel better about pre-mix, and with pre-mix I’m sure it’s getting lubrication.”
- Me: “But you just said you aren’t having a problem… “
- Caller: “Well, yes, that’s true but I’d just feel better with pre-mix”.
And around and around we go.
My view is this, the reliability of the Mikuni oil pumps is stellar, and the effort to remove one and move to the hassle of pre-mixing is simply not worth it, and in fact, misguided. The only exception *may* be racing/competition where absolute weight savings is important.
To date, I have not removed a working oil pump nor have I provided advice or assistance on how to do so. And… I don’t expect to in the future.