oil restricting o rings

Hi all, just a quick question after re-building a top end on a gpz 750, the oval o rings with with the metal  in the middle and hole that fit either side of the barrels to seal the oil ways to the head, what is the restrictions actually for ? is it so oil has more pressure to reach the oil cooler ??  Just curious.
regards

I believe it's to keep some oil in the head for starts - maybe in case you're stopping and starting a lot. 

As an aside, I'd recommend using some Yamabond or similar on those o-rings. I didn't and have slight leaks on both sides of the head. 

I personally don't understand what restrictors you are referring to.   If it is the oil nozzles on the cylinder barrel sides, are simple Y splitters to feed the two cylinder head oil galleries; intake and exhaust.  The head has two holes on each side aiming up to the camshafts.    The Oval-rings are simply sealing the oil so it won't leak out from the head/cylinder joint....or into the cylinders.

In any case.....oil goes from oil pump to the oil cooler, and then up to crankshaft and head, thus oil there is way past the oil cooler.   The early (non-GPZ) KZ750-4 to the USA did not come equipped with oil coolers, and had same nozzles splitters part numbers.

Hi thanks for the answers, its gpz turbo and the oval rubber o rings have a metal center with two small holes in it.

Most likely to insure that the turbo gets plenty of oil.

They enure the oil system pressure is high in the bottom end because of the plain bearing crank. Otherwise the oil gallerys at the cams would just dump all the oil and the relative pressure in the entire system would be low. The KZ1000 doesn't need these because the roller bearing crank doesn't need high oil pressure.

obviously this diagram is for the base model and is slightly different form the turbo, but basically the same. Notice how there are orifices before every other oil circuit  except the crank journals.

 

Great explanation, i can see where the cylinder meets the bottom end that there are two so between cylinder and the head these two are to ramp up the oil pressure even more.
Thanks Doc