Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: Matt_Harrington on August 16, 2023, 05:27:26 PM
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Is there a diagram showing the flow of oil in the 400 like the one that is available for the 750? I don't seem to be able to find one.
The reason I ask is I'm trying to understand how so much metal got pumped around the original engine rather than the filter / strainer stopping most of it.
Does all oil go through the filter? Or does some bypass it?
It was highlighted by the fact that the oil restrictors for the head had half of the holes blocked on one of them with tiny metal fragments.....
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All the oil goes through the filter, unless the valve in the oil filter bolt is stuck, in which case it will bypass the filter. Maybe check the valve is moving?
I had the genuine oil flow schematic for the CB500, printed on a large cardboard plate. Nicked it from Queenies when they were throwing it out along with one of the full engine in an exploded diagram. Unfortunately the shed roof leaked on them and ruined them :( :( :(
Isn't there one in the workshop manual? the 500 has one.
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All the oil goes through the filter, unless the valve in the oil filter bolt is stuck, in which case it will bypass the filter. Maybe check the valve is moving?
I had the genuine oil flow schematic for the CB500, printed on a large cardboard plate. Nicked it from Queenies when they were throwing it out along with one of the full engine in an exploded diagram. Unfortunately the shed roof leaked on them and ruined them :( :( :(
Isn't there one in the workshop manual? the 500 has one.
Mmm, just seen a flow chart - the implication is that if the relief valve operates, then the oil returns to the sump. (unless I'm mis-reading it)
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I have just taken the oil bolt out and the 'cup' the spring rests in has quite a deformed edge to it. so I'll replace that just in case.
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That's the oil pump relief valve Matt.
All the gearbox and primary shafts are lubricated by the oil splashing around. The 550 got a small little pump on the end of the countershaft, I don't recall the 400 getting that
Just a thought but maybe the filter blocked at some time in it's life, the valve opened allowing all that swarf to pass around the engine before the filter was changed again
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Yes, that is a possibility. I threw out the old filter by mistake otherwise I could have inspected that.
The whole bolt assembly isn't that expensive, so may just replace completely.
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If you need the insides I have some spares, waste throwing away a good bolt head, if the heads knackered anyway no harm done.
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Just something I have noticed the better bolts as well as some having more cross drilled holes for the oil through flow in the shaft also have different end bolt head size 17 mm .
I think you can fit the CBX1000 bolt 15420-300-020P others here will confirm iirc.
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If you need the insides I have some spares, waste throwing away a good bolt head, if the heads knackered anyway no harm done.
The head is fine (17mm) but the 'cup' is not - let me know....
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Original bolts have a 14mm head. Insides should be the same though.
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12mm Ken, so it couldnt be overtightened in theory! 3/16 whit hammer fit when rounded
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That's the oil pump relief valve Matt.
All the gearbox and primary shafts are lubricated by the oil splashing around. The 550 got a small little pump on the end of the countershaft, I don't recall the 400 getting that
Just a thought but maybe the filter blocked at some time in it's life, the valve opened allowing all that swarf to pass around the engine before the filter was changed again
I'm pretty sure the 400 has two oil pumps Ken although they are both housed in the same oil pump body. The main pump is for the crank, big ends, valve gear etc. The smaller pump (the rotors are about 3mm thick) pumps oil to the gearbox shafts. Both pumps are driven by the same shaft with a pin driving the main pump via the inner rotor and a flat face machined onto the end of the shaft to drive the inner rotor of the gearbox pump.
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That's the oil pump relief valve Matt.
All the gearbox and primary shafts are lubricated by the oil splashing around. The 550 got a small little pump on the end of the countershaft, I don't recall the 400 getting that
Just a thought but maybe the filter blocked at some time in it's life, the valve opened allowing all that swarf to pass around the engine before the filter was changed again
I'm pretty sure the 400 has two oil pumps Ken although they are both housed in the same oil pump body. The main pump is for the crank, big ends, valve gear etc. The smaller pump (the rotors are about 3mm thick) pumps oil to the gearbox shafts. Both pumps are driven by the same shaft with a pin driving the main pump via the inner rotor and a flat face machined onto the end of the shaft to drive the inner rotor of the gearbox pump.
You are correct Dave and the gear box pump is sealed with 3 o'ring ;)