Oil injection question

Twigg1012 · Oct 27, 2022

1990 SP 587

After more reading I've become concerned about the oil injection system on a ski I just bought. I bought two, one was supposedly converted to premix by another owner, and the other was supposed to still have the oil injection.

The previous owner put a different rotary valve + 44bn carb on it, I am now realizing there is only one cable connected to it (throttle), should there be a second to control the oil injection? More importantly, if said cable is disconnected, how big of a problem is that? Will it just use more oil or will something get damaged?

Spider4real · Oct 28, 2022

I am guessing yours will be the same or similar to my white 587 engine. There should be a short cable that runs from the oil pump to the carb. It should be hooked up to the throttle control assemble. So the more throttle you give, the more oil is consumed.

If this is missing then the oil pump will default to almost zero oil being pumped. If this is the case one outing will kill the engine. It happened to me.

If you have been riding it like this and nothing happened yet then maybe the oil pump was somehow locked in a position where it is always pumping at the max or at least a sufficient amount. Have you been consuming oil?

etemplet · Oct 28, 2022

I was told that with a broken cable the oil pump defaults to a wide open condition. My first ski was a 587 and the oil pump cable was disconnected. I thought the engine would be damaged but it was not and after reconnecting the cable properly the engine is still running years later.
I would imagine in some instances the lever would not default as designed which would be very bad.

Spider4real · Oct 28, 2022

Well mine is spring loaded. And it wants to go lean. The cable holds it in the correct position. If the cable disconnects if only has one way to go. And I toasted my engine. I had heard the same thing as you that it should go to a wide open position so I thought it might have been assembled wrong, but after studying it carefully I saw no way to reverse it. And even if I could reverse it, it would only force the oil pump in the max position eliminating the point of the variable flow pump.

Anyway, I only know for sure how mine works and I know it is working correctly. Maybe there are other pumps out there that do something different.

So the only thing I can suggest is if the pump is not connected to any cable and you are relying on it, do not use it until you verify what it is doing. Either way you need to hook it up. Either I'm right and you are going to damage the engine or I'm not and you are burning to much oil. Not as bad, but still not ideal.

Please keep us posted. Cheers

awdunn · Oct 30, 2022

Subject to correction... It appears you have a hybrid - in that the '90 originally had a BN-38, but has been replaced with a BN-44... SO ... I think the connections are different, *and* the oil metering cable is different, so you will have to somehow adapt.
The '90 mx manual pictures the oil pump control attached with a [apparently] shielded cable [which is also true on later models with dual carbs.. but for the 1990, I do not know / cannot find how the oil metering cable is connected to the throttle position]
- Unless you are premix, yes, the oil pump metering lever / cable must be linked to the throttle position, or else the engine gets lots of oil [or NO oil ? .. see discussion below.]
- The cable pulls the oil metering lever counterclockwise as the throttle is pressed. If the oil metering cable breaks, or otherwise comes off, the lever springs [relaxes to] about 3/4 turn clockwise. Usually, moving [clockwise] would mean less oil - so one might think that the relaxed position results in NO oil injected. HOWEVER, I *THINK* -- that in the fully relaxed position, the internal construction allows a full flow of oil - so that IF the metering cable breaks or comes completely loose, the engine just eats more oil instead of siezing from no oil - which makes engineering sense. [That happend to me once, where the oil metering cable adjustment backed off and out. If similar happened to another person and engine siezed, I might suspect a different reason... but what do I know? ]