Which Oil Pump Do I Have?

[BlueR32]

While researching replacement oil pump cables I just discovered Tech Bulletin M8-015C in the library which describes two different oil pumps for 250/350 twins. What's not clear to me is which one do I have in my 1975 RD250 motor. I would assume the later model but can someone confirm? Is there a way to visually check?

[m in sc]

fyi, the 250 and 350 pumps are also different, the ring gear in there is a different tooth count between 250/350.

do you have a pic? the later ones will typically have the pin retainer tab under the nut on the end of the plunger shaft that holds the pulley on.

[BlueR32]

I think I found the answer. The Tech Bulletin in the library appears to be missing Page 1. I found the full bulletin (attached) and on Page 1 lists the engine numbers for old vs new.

[Arrow]

Yeah, basically the difference is between A/B models and 250/350 variants.

The pdf isn't working for me.

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[m in sc]

see if this works:

[BlueR32]

My engine number is 352-306071 which would mean old-style pump. Here are a few pics in case it might have been replaced with a new-style. Can anyone confirm or do I need to pull the worm gear out to verify?

[BlueR32]

Forgot to add.....oil pump cable length is 325mm outer and 575mm inner in case it helps.

[m in sc]

looks to be the newer style pump, but im no expert.. did it ever have issues? id feel ok running it.

[BlueR32]

This is the motor I picked up at Barber VF last year so I've not yet had it running. I bench tested the pump and it seems to work. The issue I'm having is which cable do I need ... the old (longer) one or the new (shorter) one. The cable I have is frayed. I have a Wanted post out for a replacement:
http://www.2strokeworld.net/forum/index.php?topic=4174.0

[Arrow]

Looks like the old pump to me. Interesting how it says the later 350 has a 214 part numbered wormshaft; fine with 9 threads.
The 214 shaft actually has 7 complete threads.
Never seen 9 threads on the 350.

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[BlueR32]

Pic of the worm shaft. I would guess this is the old-style (coarse). What say ye?

[m in sc]

does it slide into the pump and turn it smoothly? to me, thats the bigger question. 

[BlueR32]

Yes it slides in easy and turns the pump no problem.

[Arrow]

Thats a 5 turn shaft. Meshes with a 40 tooth pump gear, RD250A.

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[Arrow]

You will need a new seal for that shaft now.

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