Flash and oiling system

[Anonymous]

I now have my GS1100E cases split and all components completely removed. What struck me on first observation is the amount of flashing that is on EVERY surface edge that is not machined. I also found a bit of it that had broken loose during the years of hard riding, and was trapped in the pickup screen. Any particles that get past the screen, pass throught the oil pump and are ideally blocked by the oil filter. I does bother me though. I've rebuilt many car motors and have never seen the amount of flash present here. Maybe it's just from the casting process on aluminum.

Inspecting the oil galleries, it looks as if there are two separate oil delivery systems from the oil pressure sending unit forward. One that delivers oil to the mains and the other that supplies oil to the head. The delivery to the head is accomplished through the 4 head studs on the corners of block. If I could post a pic of the top half case you could see how clean those studs were wrt the rest of them. I would have liked to post this and then ask a 'trivia' question to see who can answer why they were so clean. It might have been fun.

Something that I noticed, however, that made me step back a bit. When I was taking out the oil pump I tested the tightness of the screws on the oil pump cover. They were all a bit loose. I could hand tighten them easilly from their current position. My oil pressure was low at an idle before teardown. I wonder if this was the problem. I wonder how many bikes out there have this 'problem'? Kind of a pain to check as you need to remove the clutch basket. For those that are not afraid of this task, winter might be a good time to check it out.

Before this goes back together the dremmel tool will get a workout that's for sure. I have pics that are available if anyone wants them.

[Anonymous]

Ok, I just finished looking at some more of those oil passages. In particular, the oil passages connected to the two threaded connections on either side of the oil filter, presumably meant to be used for an external oil cooler. It looks as if they do allow oil from the pump to pass through the cooler if an external one is used. They do not force all of the oil through the cooler however. The configuration suggests that only a percentage of the oil will actually pass through the cooler.

With an external cooler present the oil flows from the oil pump to a split in the passage that allows oil to flow either to the filter cavity (larger passage) or alternatively to the external cooler (smaller passage). The oil passes through the cooler and enters the block through the second coupling where it is directly routed into the filer cavity. So, one path is from the pump to the filter through a large oil passage (less resistance). While the other path is from the pump to external coupling (smaller passage = more resistance), then through the cooler to the other fitting (more resistance), and finally to the filter cavity (smaller passage = still more resistance).

How much oil is going to pass through the cooler? I won't commit to that right now, I'm just trying to understand the system so that any modifications work as expect and I'm not throwing money away on gadgets that don't work.

If one was ambitious enough this portion of the oiling system could be calculated if all of the passages were measured for both diameter and length and the fluid resistances understood for the right angle changes in direction for said passages. I think it would be safe to say that < 50% of the oil from the pump actually passes throught the filter.

Next is an analysis of the top end oiling is anyone is interested. I don't know if my ramblings are doing anyone any good, but there they are anyway.

I have a small hand drawn diagram of this part of the oil gallery, but I can't display here. If you want it email me and I'll send.
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[Anonymous]

It's definately interesting,
I for one would like to know why my intake cam lobes are nice and shiny but the exhaust lobes are greyish and look to be scuffed. Perhaps your upper end study will show why.

Steve

[saaz]

Thanks for the first hand info on the oil passages to the cooler. This has abeen a topic of interest to a few. I run a 78 GS1000 (had it since 1980) so have to run a full flow oil cooler adaptor. Perhaps it cools things down a bit more than GSX1100s? You are right about the oil passages to the head and mains. My factory manual has a pictorial of the oil pathways - after the oil filter the paths split off to the transmission side and bottom/top ends split off.