Hello together,

as I dismantled the right covers from my actual RT3 restoring project for polishing I noticed a lot of two stroke oil around the oil pump. So I decided to give it new oil seals and check if everything is clean inside.
Opening the pump it was obvious that somebody had opened it not too long ago and put much too much liquid sealant on the housing. I found silicone wherever it shouldn’t be … and realized that one of the worm gear pins was missing. Seems that the former owner lost it during his “work” and put it together with only one. Fortunately the spring was still inside its hole in the rod. I looked for this tiny part but couldn’t find it in the parts list. But a hardened steel nail will also do it. If you ever lose one of these pins which are spring loaded inside of the worm gear take a 2mm hardened steel nail and cut it to 3,5mm.


If you now feel like overhauling your pump - it is no big deal. You require the two oil seals. It’s no need to take the original ones. You can use much cheaper standard oil seals 10x21x5 and 14x25x5. You further need a small sheet of gasket paper 0,5mm and some liquid sealant like Hylomar or something silicone based. And lay one plunger shim of 0,1mm (Yamaha 137-13137-00-10) beside if it is necessary to adjust the pump after finishing.

Best regards
Franjo

Did you replace the plunger seal?
Replace the grease?
Epoxy the cavity stop?
Machine the plunger rod?
Check the ratchet direction?
Make sure the pulley doesn't bottom on the tall head socket screws?

Ditto on what DEET said. Plus those 2 little springs and pins are critical. I don't think I'd trust that pump.

I love a good work around but I think you can do better than a nail. Not the smoothest of manufacture and questionable material. A 2mm drill bit end with the manufactured side facing out makes a nicer replacement. I would also put it in a cordless drill and carefully take a little bit of its square edge off on a smooth grinding wheel with the drill running to shape it like the oem. Polish the same method on some fine wet and dry .
Once your end is shaped and polished you can cut to size and clean up the spring side end which is not as critical.

Thank you all very much for your very helpful tips.

Did you replace the plunger seal? - No
Replace the grease? -Yes
Epoxy the cavity stop? - No
Machine the plunger rod? No, it had no edges built up.
Check the ratchet direction? - Yes
Make sure the pulley doesn't bottom on the tall head socket screws? - Yes, clearance is enough

After reeding your advices it was no questions opening the pump again and doing it better, like Kenny suggested. Specially because I overlooked the tiny plunger seal. Maybe I need some new glasses in my spectacles.
When I did it the first time I refered to YamaMoto Manual:




But now I found something better:
www.motorcycleclassics.com/mc-how-to/yam...utolube-zmmz16jazhur
Also interessting that the rubber plug Deed called 'cavity stop' came out very easily. I cleaned it carefully and sticked it with epoxy.
At this point the part number of the plunger seal (which is a 5.5x9x3 oil seal) might be interesting for someone: 93104-06108
Some other Yamaha Autolube pumps in other models have a 4x9x3. If you have this type you need the part number 93104-04001
Have the pump open again I also made another wormgear pin from the polished end of 2mm drill bit.

Thank you very much for your help
Franjo

Great work and information! Thank you Franjo.

I looked at the article and found several glaring things they missed.
There is so much more to know.
That oil pump was NOT ready to use for any length of time.

Maybe the article was written to push HVC parts.

I've never seen good documentation on oil pump rebuilding which is why I recommend sending to DEET... there's no substitution for his vast experience at something as critical as rebuilding the oil pump!

(at the same time I support "DIY" efforts... especially when they involve ingenuity! Can't get the experience if you never try... heck I've screwed up a lot more stuff than I care to admit.... that's how I learn sometimes... )

Can you explain these points or are they "top secret"

Epoxy the cavity stop?
Machine the plunger rod?

I've read this thread but no one has mentioned how they got the worm gear pins back in place with the springs. It seems impossible.