Hello - appologize if this is common knowledge but I haven't found info by searching for "oil pump banjo".
On my CT1B the oil pump inlet, and outlet, don't have banjo fittings but instead both have 90 deg elbow fittings.  They don't have any flats to wrench them off...does the one for the outlet have the infamous spring and ball check valve underneath?  How to remove and inspect to insure all clean and clear?
Thanks,
Joe M (bike was a mystery siezed engine deal).

Greetings, i'm not sure of the answer but wonder if it's had a pump fitted of something else.
The parts link below still shows a banjo fitting. Hope others can come up with an answer but i guess the fitting just twists out to get at the ball & spring.
www.partzilla.com/catalog/yamaha/motorcycle/1970/ct1b/oil-pump
I just randomly went up a few years & found one--not that i suppose it helps. Confused me for a bit, but is yours a straight on fitting to pull out to get at the spring etc & the line in is right angled.
Looking at both in the drawing had me confused but two seperate items angled one in & straight one out.
www.partzilla.com/catalog/yamaha/motorcy...1974/dt175a/oil-pump
Sorry, you say 90 degree on both fittings.
I guess if it pump as it should then ya halfway there & unlikely to be the cause of the seizure even if not pumping 100% correct amount.
Pump is adjustable for stroke with washers under the plate, well, minimum stroke adjustable at idle or closed throttle but that adjustment won't affect maximum delivery or only by next to nothing in the total open throttle stroke.
Cable adjustment is reasonably important so as to get the stroke up there on open throttle.
But i still think it'd need to be a long way out or have a broken pump cable to cause seizing.
Then again i run mostly premix so what would i know haha. They were 100% reliable when i was in the workshop back in the CT1 days but now we're 50+ years later.

my 75 400b has what you have on the pump. Yes the ball and spring is in there, you have to get a rag on it and grips, then turn back n forth and it will come off

Hello Again, yes, my pump has two 90 degree fittings.  I took everything apart (except for the fittings) and can freely back flush the larger input.  But the smaller output fitting, its damn tight.  Will get more aggressive with it tomorrow but new concern is I let my teen son strip it down and he/we lost one of the sprag pins.  Anyone know how to get or make one?  PN 936-01040-29-00.  Worst case will get a block off plate and go pre-mix but would like to re-build the pump if I can get that part.
Regards, Joe M 

Some ideas in this thread...  probably best to get another pin if possible though.

yamaha-enduros.com/index.php/forums/1972...worm-gear-pins#49804
 

Wrecker should have an old pump. Pins are probably the same on all.
I shouldn't even suggest it would still work ok with only one pin & spring.
So i'll consider myself reprimanded.

You say you have been back flushing it--not sure about that--do you mean to say forward flushing--just flushing it through the right angle 'in' union fitting from the tank then coming out the bleed screw on the side.
Don't think i'd try forcing oil through the pump & out the union fitting up to the cylinder as oil is compressed--maybe not compressed but pumped via in the center shaft & sent to the 'out' union at timed intervals then past the ball & spring.
Maybe i'm reading your story wrong. I do get my wires crossed sometimes.
ps, to fit a block of plate for premix the clutch cover has to come off & pump drive shaft plus steel bush removed.
Now i've forgotten what bike we're talking but they're all the same in that respect.
Also the pump internal gear has to go the right way around or it'll just slip around over the spring pin & do nothing, [or work good with motor running backwards] [don't go there].
Ignore me--nothing worth watching on TV tonight. You'll be the pump expert after this.

I seem to remember recently , HVCCycle advertised replacement pins for Yamaha oil pumps .
Try their website .

Thanks Swoop - they do have the pins...and some other interesting parts.
hvccycle.net/

When I meant back flushing, I just meant spraying WD40 into the pump placed on the workbench.  I also got the output barbed elbow out.  its pressed in, not threaded.  Not sure how many times you could remove and replace it without it being loose but I wanted to see the hidden ball and spring underneath.  When I put the fitting back in probably will add some type of locking compound for insurance.  Everything is now all apart and this will be a carefull rebuild!
Joe M
'70 CT1B in Santa Clara, CA

Careful, some pins are too long to clear ring gear flats.

cliff

Well, I received new sprag pins and a pump rebuild kit from HVC.  Came pretty quick.  The sprag pins are approx .5 mm longer and have a light chamfer on the edges. I figured out how to install them by tightly gripping with tweezers and aligning over the spring hole from "behind" the partially installed wheel. Then was able to push in the pin and push wheel on top of the pin with my finger tips  Also able to do this to the second pin.  I have jittery hands so think its doable by others..or enlist spouse or youngster if you have big paws...
Anyway, with the longer length it does fully rotate, but is somewhat scratchy in feel  What is the actual function?  How much spinning does need to do?  Suppose I could take out the pins and sand some radii on them....

Second issue is the main plunger shaft seal (the tiny / smallest seal) I received is much too small (ID) to work.  I confirmed my plunger / pump is correct for a CT1B and its dia matches the seal in the 69-71 AT-CT parts manual (ref 13-8). This is another puzzler, and waiting for clarification from those guys.
Cheers,
Joe M
Santa Clara, CA
(this one bike - CT1B, but:
'67 Land Rover 109SW (driving)
'74 SIII 88 (derusted and partially back together)
'56 MGA (driving)
'60 AH 3000 (rolling chassis with parts strewn)