This may be of interest to some of you:

Nice long "autolube promo" video with some nice analogies for those who wonder how the pump regulates the oil under varying conditions.

Two comments...

1. That silver metal plate with the hole in it that bolts under the pulley nut is supposed to be bent down and touching or (See warning about washer touching the pin from DEET below)nearly touching the pin. It's purpose is to prevent the pin from falling out. If the pin falls out, the pump will be stuck on "minimum". This might be the most common failure point (yet still extremely rare) of a pump that has been reasonably cared for. Early models did not have this protective washer... on later models Yamaha used a tiny thread on the pin instead of a press fit and again no "retaining washer".

2. Contrary to the video, I've never had that much trouble aligning the pin with the correct pulley mark... The glaring omission is that the pin is supposed to align with the mark when the throttle slide just opens rather than with "throttle closed". If you adjust at "throttle closed", then when you twist the throttle and take up the slack in the throttle cable, the pump pulley will be already be rotated past the mark as the engine starts to rev. This will over-oil the engine... and is a very common reason for excessive smoke/oil during low throttle cruise conditions. (If you have a fair amount of slack in the throttle cable, the amount of excess oil can be significant.) I like to start the engine and rotate the throttle while looking at the pump alignment marks... just as the engine picks up RPM off idle, the oil pump marks should align.

P.S. DEET has likely repaired more of these pumps than anyone. Below he says he's seen many pumps fail to pump due to the washer being bent into the pin. The pumps are simple yet complex with some very tiny parts inside... I continue to recommend anyone with concerns about their pump send it to DEET for a rebuild.

WARNING
Under NO circumstances let the pin touch the plate. If it does, the pump will stop working.

Do NOT try to push the pin in deeper.... it will lock up the pump.

My advice is to remove the retaining plate or bend it outward so the pin cannot touch.
IF IT TOUCHES the pin, the pump will STOP pumping.

I have seen a lot of pumps that failed because the retaining plate came in contact with the pin.

When I restore a pump, I install a new pin that will not come out and in most cases, I delete the retaining plate.

I can’t express just how delicate this part of the pump is. Whereas there is an unnecessarily strong cam drawing the oil in.... there is a small spring pushing the oil out. It should be the opposite.
The cam movement is unstoppable. But if the spring encounters resistance beyond its capacity, it will stop pushing the oil.

Thanks for the correction DEET!

I've never had a washer that needs to be bent to provide a safety retainer for the pin as the one in the video appears to need... plenty that are close to the pin. I've also seen one "failed" pin. It was loose and only held in by the washer and the pump still worked. (I also remember Meis had a pin fall out at one of the Endurofests and made the whole event... wondering why he wasn't using much oil.)

Thinking about what you said makes perfect sense! If that washer were to drag on the pin the pump plunger would go "up" and not return. The pump would visually stop working.

As I've said many times, best option is always to send the pump to you.

You know.... back in the old days at the dealership, we never opened a pump for any purpose. We ordered a new one.
Yamaha stopped showing the internal parts diagrams and no one had been trained on how to service them. Back then, it was easy to get one. Now, not only are they hard to find, but you need a secret decoder ring to figure out what engine it is for.

Kinda reminds me of printed circuit board technology. It used to be no big deal to run down to Radio Shack for some replacement resistors or capacitors in order to repair a board. Now, we just toss the whole thing and buy a new assembly. It would take an electron microscope to work on them now!


One of these days, I need to write down what I may know about this stuff to pass on to future Enduroholics...

great info guys... I appreciate the in depth discussion
I have bookmarked this thread so when it is not minus 15, I'll get out to the garage to give mine a look

Great info guys thanks. I have rebuilt the oil pump on my DT 175B but have not installed it yet. Would it help to put some blue loctite on the pin?

This video really helped me understand how to adjust the pump correctly, I have read how to do it but with the visual aid it became clear. I copied his the tool he made for priming the pump since I put a new line on from the pump to the carb, that made it go by really quick in getting the oil from pump, through new line, to carb. Also would like to thank DEET for his remarks on the pin, very helpful as well.