XS650: Oil Pump   Leave a comment

The Heart. Development Engineers must have been a bit prescient. Perhaps they foresaw the modern coronary constipation evidenced in our consumer society. Early pumps, up to XS1B and F, # 004130, were produced with pressure relief valves, dumping directly into the sump. So, not that many left lying around now. Imagine that. Your own coronary bypass-Yamaha, Year of ’69.


XS1B-F oil pump with prv


The housing was redesigned. Subsequent  engines had no prv. The filter bypass was left to direct oil past blocked filters to the engine.


pump driven direct from motor…note: tacho is driven off the pump drive…if the tacho stops working so may your oil pump…don’t leave it to speculation


The pump is direct driven off the motor. It wears. Even faster when you don’t change the oil regularly and control the sieve. Metal shards off the gears, pieces of clutch primary spring etc pass through the pump. If you’re lucky. To the filter, which thankfully, actually does a good job. Note. Watch your Tacho. It’s driven off the oil pump drive. If it stops working, STOP. Your oil pump may also not be working. Check it out. Immediately.






check rotor to impeller clearances .. 1-rotor.. 2-impeller..3-setup marks


filter…point of last resistance…primary springs here had remained in sump, thankfully, the rest had already been intimate with the pump


XSJohn, RIP, spent some time improving his pump efficiency by fine tuning the tolerances between the housing and impeller-rotor. If you do this make sure your sieve is doing more than just sieve.


xsjohn, rip, improved his pump efficiency


new rotor and impeller


50+ oil pump


Also available are the 50+ high-volume pumps-originals pump around 7.5ltr per min @ 5000rpm. Similar to those produced for the SR500 by KEDO. I’ve fitted one to my XS. Not totally convinced. The galleries are all still the same. Means the pressure and-or flow must increase. May also have some cavitation at source if running alternative sump filtration? Tests with paper filters however, have shown a suction drop of only 0.1 bar or 1.5 psi. I can see distinct advantages if enlarging oil galleries or feed and if adding a cooler directly from the filter. I would like to see a prv on these.


Posted January 16, 2011 by xscafe in Motor - Oil

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