Post by wayne on Aug 20, 2011 2:09:26 GMT -5
If you've been following the No Oil pressure thread HERE, here's the solution:
The short answer......the large O ring that seals the points case to the trochoid pump case was too thick. It was not allowing the underside of the points case to form an adequate seal against the trochoid pump face and the mating surfaces of the pump casing which form the pump inlet and outlet passageways.
Be warned, I don't remember where I got this O ring but it would have been from a Suzuki dealer. Either Suzuki changed the spec, or the seller substituted a similar O ring. It doesn't work. It cost me several days of hard work (5 clutch cover removals) and quite a bit of money in oil and gaskets.
That's it. Read on if you're keen.
The new O ring is about 3.5 mm thick, the O ring that I'd bought years ago is about 3.0 mm thick. This difference in thickness is not due to the flattening of the old O ring. But in the channel in which it fits, the difference was even greater, close to 0.9 mm (due, I suppose, to the thick O ring being squished and skewed in one direction).
After I'd found that the problem bike worked using my other bikes complete oil pump/casing and points case, I knew the problem to be in there somewhere.
The thing was, the low pressure pump met all book tolerances so I was suspicous that it was the problem but decided to swap rotors with my good bike. Glad I didn't order new rotors.
I was about to swap pump rotors but decided, for the hell of it, to measure everything as it came apart. One measurement I did was the depth from the trochoid pump casing to the surface of the O ring. I was surprised to find a big difference. I had a couple of old O rings and noticed that both were the same thickness but 0.5 mm thinner than the new one.
I reassembled the problem bike with all its own components, the only change I made was to use one of the old, thinner, O rings.
On start up, the pump self primed instantly (the inability to do this was the start of this problem....see "no oil pressure" thread).
Presto.......correct oil pressure through the rev range. Up from 2.25 kg/cm at 4000 rpm to 5.2 kg/cm (min 5.0).
I can't believe how much time, oil and effort I've wasted on this problem. Hope it helps someone.
Wayne
The short answer......the large O ring that seals the points case to the trochoid pump case was too thick. It was not allowing the underside of the points case to form an adequate seal against the trochoid pump face and the mating surfaces of the pump casing which form the pump inlet and outlet passageways.
Be warned, I don't remember where I got this O ring but it would have been from a Suzuki dealer. Either Suzuki changed the spec, or the seller substituted a similar O ring. It doesn't work. It cost me several days of hard work (5 clutch cover removals) and quite a bit of money in oil and gaskets.
That's it. Read on if you're keen.
The new O ring is about 3.5 mm thick, the O ring that I'd bought years ago is about 3.0 mm thick. This difference in thickness is not due to the flattening of the old O ring. But in the channel in which it fits, the difference was even greater, close to 0.9 mm (due, I suppose, to the thick O ring being squished and skewed in one direction).
After I'd found that the problem bike worked using my other bikes complete oil pump/casing and points case, I knew the problem to be in there somewhere.
The thing was, the low pressure pump met all book tolerances so I was suspicous that it was the problem but decided to swap rotors with my good bike. Glad I didn't order new rotors.
I was about to swap pump rotors but decided, for the hell of it, to measure everything as it came apart. One measurement I did was the depth from the trochoid pump casing to the surface of the O ring. I was surprised to find a big difference. I had a couple of old O rings and noticed that both were the same thickness but 0.5 mm thinner than the new one.
I reassembled the problem bike with all its own components, the only change I made was to use one of the old, thinner, O rings.
On start up, the pump self primed instantly (the inability to do this was the start of this problem....see "no oil pressure" thread).
Presto.......correct oil pressure through the rev range. Up from 2.25 kg/cm at 4000 rpm to 5.2 kg/cm (min 5.0).
I can't believe how much time, oil and effort I've wasted on this problem. Hope it helps someone.
Wayne
