engine builders, need some advice

Just finished bolting my 750Gpz's motor back together last night, and went back over the book as a checklist, because I did not have it for the cylinders install, and wanted piece of mind.

I don't have it.

On the bottom end at the outer edges are two oil passages that some reducers go in -- big hole one end, small the other. I think, I think that I put them in big hole up vs big hole down. Pretty sure.

Now we three bonded the gaskets and like I said, torqued the bolts last night. Will I be able to reuse the gaskets (base, head, cylinder I know should be all right) if I am careful, or do I go ahead and get new ones?

And if the oil passage is flipped, I can see that the spray pattern will be affected, but I don't know how much. If I decide to do the stupid thing, how bad do you think it would be, what does these passage restrictors do?

Or might I be the first among the current group to find out?

Thanks guys.

Never heard of restrictors, but then again I never had that bike

gpzrox wrote:

Just finished bolting my 750Gpz's motor back together last night, and went back over the book as a checklist, because I did not have it for the cylinders install, and wanted piece of mind.

I don't have it.

On the bottom end at the outer edges are two oil passages that some reducers go in -- big hole one end, small the other. I think, I think that I put them in big hole up vs big hole down. Pretty sure.

On mine, the restrictor tubes are between the top of the cylinder and the head in the oil feed pathway.

Is there a pair of O rings on the ends of these restrictor tubes?


gpzrox wrote:

And if the oil passage is flipped, I can see that the spray pattern will be affected, but I don't know how much. If I decide to do the stupid thing, how bad do you think it would be, what does these passage restrictors do?

I thought they were there just to "valve" the amount of flow in that pathway, and keep some backpressure to balance the distribution of oil into the other areas.

I'm not sure what flipping it will do? Seems like it should still function as a restrictor. I am not an expert on the 750 four, my 750 is a twin.

gpzrox wrote:

Now we three bonded the gaskets and like I said, torqued the bolts last night. Will I be able to reuse the gaskets (base, head, cylinder I know should be all right) if I am careful, or do I go ahead and get new ones?

I suspect that stuff will tear the gaskets taking them apart, it is super strong. I had to tear mine back apart on my last rebuild. I used the old base gasket and valve cover gasket to cut new ones from the best gasket material at Pep Boys, and it worked very well. I did reuse the head gasket because it had only a couple of hundred miles on it. I used some copper spray on gasket sealer. Obviously, installing a new gasket would be better but mine worked.

www.bikebandit.com/houseofmotorcycles/ka...gpz-750-1982/o/m9936


I see what looks like a flow restrictor at the top of the crankcase on this GPZ 750 crankcase drawing, it's number is 92062C. It's called a nozzle. Is that the one?

On mine, the restrictor tubes are between the top of the cylinder and the head in the oil feed pathway.

Is there a pair of O rings on the ends of these restrictor tubes?

The ones cylinder to head are easy: you can't get them wrong. Small holes on both sides. They have the oval o-rings. The case to cylinder reducers have round o-rings.

I thought they were there just to "valve" the amount of flow in that pathway, and keep some backpressure to balance the distribution of oil into the other areas.

I'm not sure what flipping it will do? Seems like it should still function as a restrictor. I am not an expert on the 750 four, my 750 is a twin.

We thought so too when we put it together, so I didn't stop there and wait for the book.

I suspect that stuff will tear the gaskets taking them apart, it is super strong. I had to tear mine back apart on my last rebuild. I used the old base gasket and valve cover gasket to cut new ones from the best gasket material at Pep Boys, and it worked very well. I did reuse the head gasket because it had only a couple of hundred miles on it. I used some copper spray on gasket sealer. Obviously, installing a new gasket would be better but mine worked.

Sounds good. I'll cross my fingers, install next week and go from there. If I have leakage, I'll make my own!

You know, the more I think about it, the more I am unable to figure out what difference it could make if those nozzles were installed upside down. The oil is being forced up the passage from the pump to the head area. The nozzle is a tube with a hole in it. That inmpedes the oil flow and creates back pressure there, but let's oil flow through at a restricted volume.

I can't figure out how it could make any difference if the restriction was a half inch farther down the flow route....?

Maybe somebody else knows a reason.

bountyhunter wrote:

www.bikebandit.com/houseofmotorcycles/ka...gpz-750-1982/o/m9936


I see what looks like a flow restrictor at the top of the crankcase on this GPZ 750 crankcase drawing, it's number is 92062C. It's called a nozzle. Is that the one?

Yeah that is it. And we will see if it causes a problem, maybe over hundreds of thousands of miles, at least I hope!