I have two disassembled oil pumps for a 1975 DT 175. They both have a washer I cannot identify. Can anyone help me out with what this is for? It's the circled washer on the top in the below photos links. They are organized by inner diameter and you can see that it should belong to the plunger. I think it may just be an extra washer that belongs below the shims since this is a 175 and maybe it needs less oil but I'm not sure. I don't think it would go anywhere inside.

• Click here for photo
• photos.app.goo.gl/2PqSTbCkJFbUJERS7

Here's one probably quite similar in layout & i doubt they vary much in internal design through the years. Could be wrong of course. Down the link page it has 'continue reading' & he gets right into the internals. Not sure it helps much but hope it does.

www.motorcycleclassics.com/classic-motor...tolube-zmmz16jazhur/

Thanks. I was looking at that one and it's not there. However, this washer is on two different pumps I have from a 175 so I think it belongs somewhere. I think it may be an extra "shim" washer that goes under the gold shims as it's inner diameter is the size of the plunger and there really is no where for it to go on the inside of the pump.

I guess as long as the tolerance is measured correctly when adjusting the shims, that's all that matters. It just drives me crazy when there's a part I can't identify... Especially on a part like the oil pump.

I'll stick my neck out lol. It won't go under the gold shims as they adjust your minimum pump stroke. If you put it under those & its pump shaft size it'd just float there & serve no purpose as the stroke bottoms out on the step on the cable roller at closed throttle. Ok re-thinking i guess on open throttle fitting it there it could limit downward travel of the plunger in hindsight, if the plunger goes 'that far in' for it to have an affect. So i say it doesn't go there!!--plus if it floated there it could-in theory-scrape the shaft floating with shaft going out & in. Does it go behind the plastic drive gear against the circlip in the clutch cover--na i guess not. So internal?. Won't be to reduce stroke as that serves no useful purpose. I'm from the days when they gave no trouble in the "60's so just gold washer adjusting & cable adjusting--lucky me haha. I think DEET on here is the pump man. Help Deet--save us please.
One more without looking again. Does it go 'behind' a seal for support--can't think why.
Another try--downward stroke of the pump isn't limited by the copper washers as doesn't go that far in for them to touch down on the pump body. I've got an old DT1 pump somewhere so better go find it & put my money where my mouth is lol.

I saw a step by step breakdown of the pump disassembly on you tube just yesterday. I’ll see if I can locate the author. 

Is it the washer that goes down against the clip before the spring?

#42 at this link of a very early pump  www.partzilla.com/catalog/yamaha/motorcycle/1965/yg1tk/oil-pump

#2


Yamaha Motorcycle 1976 OEM Parts Diagram for Oil Pump | Partzilla.com

Yep. That's it. That makes sense now. Kind of an odd place. I bet that washer gets easily stuck inside the pump when you remove it and then just falls out later.

It shows the 1975 B doesn't have it and the 1976 C does. Must be slightly different and why my 1975 has it who knows?

Thanks again! Appreciate it.

Unfortunately you can't rely on Yamaha parts diagrams and literature always to be correct for assembly. 

Clutch assemblies are sometimes drawn with parts in the wrong order, steering head bearing races are identified "swapped", and sometimes parts aren't shown that definitely do exist and need to be there. 

Sometimes parts listed are wrong in one diagram and then the mistake is corrected in a later year model diagram.  Or sometimes the opposite happens and the earlier diagram is correct.

That's why we're lucky to have experts like DEET as members here to help!

Rescued by Deet!!. I never thought there'd be a washer there. Actualy never new there were different spiral drives either on different pumps. Pumps never gave trouble--in the old days.