MZ/MuZ Riders

In assembling the 660 cc crankcase, there are conflicting messages between service manuals out there.


Mz says, keep Yamaha Bond away from the oil galleries.


Raptor 660 (Yamaha) says, put sealant around the oil passageway.


I followed Mz and left the oil passage dry (no sealant) inside the case; will I have problems with oil pressure?

Would anyone know if the oil passage centered in the case halves is low or high pressure?

IMO the information from both manuals combines to: yes, apply sealant on the mating surface of the oil gallery, but not so much that it spills into the oil passage. That makes sense, as you do want a proper seal there, but you do not want sealant in your bearings/camshaft/... .

You will never see a leak, so you do no know how much oil will leak there, if any. Look it up yourself in drawings, but that joint may well be downstream of the pump. If it is, and if that joint leaks: yes, such a leak will reduce the amount of oil circulated, and the pressure thereof. However, the impact may not be very big. To assess the impact: what does the manual say about measuring the pressure? For the XT600 it was 13kPa @ 1300RPM at the oil filter chamber.

Good idea on checking my oil pressure. I have plans to crack the bleeder screws in hope of oil flow up top, etc.

I have made attempts to read the drawings, but did not have luck with determining the flow direction; which is why I asked.
That gallery/jacket is pretty big to be upstream don't you think? That would be a lot of volume to push by the look of it yah?
Anyway, I do not know for sure.

From the Raptor manual.

While I had several XT's, I have never had / worked on the 660, so I do not know your engine specifically.

It might be low pressure/relatively high flow coming from the pump. Note that 13kPa is almost 2PSI, so that's low, and your picture suggests similar: a low pressure system. At low pressure, it will probably not leak much, but I have no idea of the impact (if any).

Maybe there are any other views? It's always good to ask someone else's opinion, but in the end you yourself decide - it's your bike.

Thank you for the reply.