Zephyr 750 , ZR7S Oil Pan Question

I picked up a Zephyr 750 oil pan for a project and noticed that there is no oil cooler line separating plug in the oil pan.  Is this normal?  For those who have a ZR7s oil pan installed on their KZ650/750 oil cooler conversions, is there a plug present?  Reason I ask is that I noticed the oil cooler doesn't get as warm when using the Zephyr oil pan as it does when I use the GPZ750 oil pan (which has the 14mm plug).  I don't see why oil feed would divert through the oil cooler if it can simply flow upward toward the head...

 

This question has caught my attention.  I put an oil cooler on my 750E, using an oil pan with the cooler line ports drilled, but I didn't take note of this level of detail.  I think the output line and return line ports must be separated, or there will be minimal oil flow through the cooler.

Checking the parts diagrams, there is no PN for a plug between the ports.  Many times, Kawasaki doesn't sell parts that are integral with a base part.  Can you make the missing plug?  Otherwise, you may need to get a different pan.

On GPZ750 oil pans there is always a threaded plug between those oil ports. That does not look "normal" from other oil cooler pans I have seen. The oiling system can't really function properly without a plug in there to separate the inlet and outlet oil flow.


 

Nessim, I have a GPZ750 oil pan that I'm getting a plug welded in place of the oil level sender, which keep leaking.  If I had to plug the Zephyr oil pan I'm sure that something can be done, but this hole seems to be intentional.  The internet is sparse with Zephyr or ZR7 oil pans that show this detail.  The only picture I found is by a member here, Gazz, and his oil pan seems to have this hole as well.  This is why I'm reaching out here to see if someone has a Zephyr or ZR7 oil pan and can report back.  

Injected, I agree that the cooling system can't function properly with that hole there, and I know first hand because by using the Zephyr and GPZ oil pans back to back on same motor.

 

 

Looking at the size of the ports in the oil pan (12mm "O" ring) and the fact that the "O" rings where the pipes join the cooler are only 8mm I suspect the cooler is only a "partial" divert rather than the full flow passing through the cooler hence the reduced size of the hole between the ports in the oil pan

 

Looking back through some photos of my engine build, it seems that I used a ZRS oil pan as well.  I can't remember, but the GPz's and L model bikes used an oil level sensor in the pan, and my pan doesn't have that provision, so...

Should I be worried?

Is the hole between the ports threaded?  It doesn't appear to be in the photos.

P1010994 by nessism , on Flickr
 

Nessism wrote:

Looking back through some photos of my engine build, it seems that I used a ZRS oil pan as well.  I can't remember, but the GPz's and L model bikes used an oil level sensor in the pan, and my pan doesn't have that provision, so...

Should I be worried?

Is the hole between the ports threaded?  It doesn't appear to be in the photos.



 

You are obviously getting oil to the top end (would have been obvious by now if not)  does your oil cooler get hot after a long run ? if the answer is yes then I suspect all is as it should be and the reduced size hole between the ports redirects a predetermined portion of the oil flow through the cooler, not all of it - I would be cautious of blocking the by-pass hole as the cooler circuit doesn't look capable of dealing with 100% of the oil flow

Leaving the plug out of the later series engines might have been a cost cutting measure, eliminating a part plus a machining and assembly operation. Kawasaki must have come to the conclusion that having a restriction in that circuit was good enough for the correct operation of the oil cooler.

Its probably not as "efficient" as having the plug in there but I don't think its a cause for concern.

The GPZ pans with the oil level sensor always seem to leak, mine leaked even after changing the O ring. I made a plug for it and had it welded shut.

Recently I converted a 650 oil pan to run a oil cooler from that front oil feed galley.



650 and 750 Spectre (sensor hole not machined)



650 modified (custom diverter plug)



GPZ750 with sensor plug welded in.

On the later oil pans they left all the cast features in but eliminated the machining. The Spectre does not use a oil cooler so there are no machined holes to attach the fittings (no diverter plug)

I plan to run a much larger oil cooler than a stock Kawasaki unit so I opted to run a diverter plug emulating the GPZ pan.

 

Just out of interest what size are these holes in the stock pan (you appear to have opened them up for your fittings) they look kind of small in the picture to carry the full flow (just my opinion)

 

Wookie58 wrote:

Just out of interest what size are these holes in the stock pan (you appear to have opened them up for your fittings) they look kind of small in the picture to carry the full flow (just my opinion)

 

 

That is a old picture, I already tapped those 1/4NPT and have -6AN fittings attached. I do remember I had to drill the proper size for that pipe thread so they were slightly smaller but I can't remember by how much, maybe .030"-.040" oversize. Maybe those holes were about .40" diameter.

The oil feed on the GPZ pan I believe takes a M14 plug. I put a 9/16-18 plug in mine because I had that tap.and it seemed really close size wise.

The restrictions thru fittings only increase pressure in that localized part of the oil circuit. I believe the ID of a -6AN fitting is .28" and the hose size is a nominal 3/8" ID.

Funnily enough the turbo oil pan is the same, drilled out & no plug, in fact back before people knew about the oil pump upgrade it was the done thing to open up the port to allow more oil thru to the turbo

It seems, then, that the engineers decided to prioritize oil pressure to the head over maximizing cooling capacity.  I'm running 810 pistons with GPZ cams and expect an increase in cylinder/head temperature so proper oil cooling is key.  

The Zephyr oil pan was installed on my, mostly stock, KZ650 for two years.  I noticed the oil cooler getting warm but never as hot as the rest of the engine, even when riding in slow city traffic.  In fact getting it evenly warm takes a very long time and even then it's nowhere near as the rest of the engine.  But with the GPZ oil pan it gets evenly hot very fast.  So... how much oil pressure and reliability is sacrificed with GPZ oil pan and, conversely, how much oil cooling is given up with the later style oil pan.  Obviously the answer will lie in installing a port in the cylinder head oil galley to measure pressure and do a back to back test.  

My drive to work involves highway speed, stop and go traffic and city driving.  Before the oil cooler was installed on the KZ650 heat soak was a real problem and carburetor efficiency would change, drastically,  after one hour of riding in these varying conditions.  I always noticed that I left home with one bike and arrived to work with a completely different one, so proper cooling is a priority.  Incidentally, I'm using a ZR7 oil pump and measured oil pressure was as specified while using the Zephyr oil pan.