SOHC.co.uk Forums > CB750
Problem with initial valve adjustment after rebuild
leadnavel:
Thanks for your assistance guys it’s been a massive help. Sorry for the delay with the update I’m in the middle of a house move and the other half (we’ll the other 3/4) had other plans for me.
Long story short… I’ve got flow to the camshaft/holders and top end gubbins, the problem appeared to be an air lock.
Short story long… I disconnected the oil hoses from the oil tank (my engine is still on the bench connected to the oil tank) to have a look to see if there was a problem. There wasn’t any oil in return pipe but the feed pipe was full. I took both hoses off and blew them through, they were clear.
I removed the oil pump, all three ‘O’ rings present and correct. The ‘stopper valve’ was also working OK. I immersed the pump assembly in engine oil
Oil Pump
https://youtube.com/shorts/WYfMHacZ3iM?feature=share
Oil Leak stopper valve
https://youtube.com/shorts/D7f3qYA43BQ?feature=share
turned the sprocket by hand and saw lots of air bubbles coming from the pump feed holes. After 5 minutes of turning I did notice the bubbles had mostly stopped and I that there was more resistance when turning the sprocket. I then removed the pump assembly from the oil bath, trying not to turn it or hassle it too much then I let it sit for a while raised up above and off the screen at the bottom, about 10mins, only a small amount of oil drained out. I replaced the pump assembly and only had to kick it over 7 times before oil started to show in the hole in the oil filter housing, result!
I did toy with the idea of using Vasoline Smoothoperator when I initially serviced the oil pump but wasn’t confident I could do it correctly, in hindsight I probably should’ve gone this route.
I then fitted the clutch basket and connected an oil pressure gauge to the outlet where the oil pressure gauge is fitted and turned the engine over using the starter motor pressure came up to 40psi after about 5-10 seconds.
Pressure Test
https://youtube.com/shorts/l6NEGcQ0b0o
Thanks again guys for taking the time to offer your assistance it is really much appreciated it's gotten me a whole lot closer to finishing the project.
philward:
Wish I'd seen this post earlier - I had problems on the 1st of 3 750 rebuilds I've done but on the subsequent 2 used the vaseline method and oil presure almost instantly
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