Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: harrycb750f1 on November 19, 2014, 09:03:17 PM
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I'm trying to get my crashed cb750 f1 back on the road but after changing the generator cover as it was cracked, I went fill it up with oil and it didn't flow into the engine. I checked the 2 pipes from the oil tank were clear and also checked the oil filter.
Does anyone have any idea what it could be or I could test/check?
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Is the oil pump working?
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The engine is a dry sump design, the pump is a two stage type that sucks the oil out of the sump in one part and puts it into the oil tank.
The second part of the pump takes its' supply FROM the oil tank and pumps it round the engine, just putiing oil into the tank will not flow into the engine until the oil pump is running (when you start the engine) at that point you should see the oil level initially start to drop in the tank as it passes into the engine.
As Trigger says, are you ok that the oil pump is going? It's accessed through the sump pan underneath the engine, If you've not worked on this and it was previously ok then you should be safe to start it if the level is high enough in the oil tank to make sure it has a good supply.
BUT worth turning it over first with the spark plugs removed and watching the oil light to make sure it gets pressure first before refitting the plugs and running it.
Let us know how you get on.
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I tried turning the engine over with the spark plugs out but the oil still didn't pass through. So I think I should look deeper into the pump to see what happening. Cheers for the advice, a lot of help.
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I tried turning the engine over with the spark plugs out but the oil still didn't pass through. So I think I should look deeper into the pump to see what happening. Cheers for the advice, a lot of help.
did / does the oil pressure light stay on ?? or go out when you spin the motor ??
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if i remember right, it stayed on
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I had the same thing on a rebuilt engine I didn't prime the pump and it wouldn't circulate oil ,
I had to take the pump off and fill it with oil and put it back on and it worked ok after that ;) cheers Mick.
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You can always remove the stopper valve cover,(2 bolts) let valve move slightly till oil flows, then retighten. Bleeds the pump through. Worked on a couple of bikes for me. Easier than removing the pump.
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This link may help you get your head round the oil circuit / pump...
http://cb750k2.honda4.nl/lubrication-system/lubrication-system.html
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I have to say guys I have never primed a pump ever.The last bike I have just finished sat for 2 years and oil light went out in seconds after starting.What I have done to help which I dont know if it helps was to lay her over and fill the main gallery with oil.Cant think of any thing else
Cheers
Bitsa
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Perfect, I'll give it ago and post how it goes
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Harry
Dont run her for long if the oil light does not go off after 10 secs STOP
Cheers
Bitsa
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If I remember right when I first ran my F1 i put the bulk of the oil in the oil tank and the rest in the engine through the rockers, even so it took quite some time for the pump to take suction, plugs out until the oil light went out.
Cheers
Dennis
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;) i think its time too bite the bullet put the plugs in and fire it up if there is any damage or wear you will hear it just keep the revs down till the oil light goes out, if it still don't go out the engine is shagged anyways, no lose no gain, if it was fine before then its no worries, tip a load of oil in the camshaft just to give it a bit of lube if the oil light is still on after a minute or two , its time for a tear down .
some of my bikes don't get fired up for weeks,it surprises me how long it takes for the oil lights to go off on some of them
these bikes just ain't new anymore ;)