Author Topic: Something isn't right  (Read 847 times)

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Offline el pachuco

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Something isn't right
« on: May 01, 2016, 08:29:32 PM »
 I'm bringing a "75 CB750 back to life. It's got 14.5k miles on it but hasn't ran in decades. I drained the oil from the tank, engine and filter. Replaced the filter and gasket, washed the tank and hoses out with Varisol, resurfaced the aluminum washers between the tank and hoses, and replaced the O-rings between the hoses and the engine. Filled the tank with 3 Qts. of oil and kicked the engine over a dozen times. The oil level in the tank remained the same. Then, with the kill switch off, I hit the starter for about 10 seconds. Still, the oil level in the tank remained the same. So, I removed the spark plugs and hit the starter for another 10 seconds and the oil level doesn't move. No bubbling of the oil in the tank. No movement of any kind. And of course, the oil pressure light remains lit. Can someone please give me a clue as to why the oil isn't being drawn into the engine. The bike was being ridden when it was parked. All cylinders have good compression and all the plugs are uniform and normal in appearance, indicating it was a good running machine when last parked.

Offline CycleRanger

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Re: Something isn't right
« Reply #1 on: May 01, 2016, 08:37:13 PM »
Pull a couple of tappet covers and see if oil it getting to the top end.

Could be the oil pump is air locked.
You may have to pull the pan and prime it.
Do you have a copy of the Honda Shop Manual or Parts List for your bike? Get one here:
https://www.honda4fun.com/materiale/documentazione-tecnica
CB750K5        '79 XL250s     CL350K3
CB750K3        '76 XS650      '76 CJ360T

Offline el pachuco

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Re: Something isn't right
« Reply #2 on: May 01, 2016, 08:44:38 PM »
How would I go about priming the pump?

Offline CycleRanger

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Re: Something isn't right
« Reply #3 on: May 01, 2016, 08:55:10 PM »
Unfortunately it usually involves removing the pump, but you're not there yet.
The other thing to verify is that your pressure switch is working properly.
I suspect your problem may have something to do with your work on the hoses.
I'm not sure if solvent would damage the inner liner on the oil lines or not but if it caused the rubber to swell
it may be preventing oil from getting to the engine.

But I'm just totally guessing, it could be none of those things. ;)
Do you have a copy of the Honda Shop Manual or Parts List for your bike? Get one here:
https://www.honda4fun.com/materiale/documentazione-tecnica
CB750K5        '79 XL250s     CL350K3
CB750K3        '76 XS650      '76 CJ360T

Offline Terry in Australia

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Re: Something isn't right
« Reply #4 on: May 01, 2016, 08:57:28 PM »
With the bike on it's side stand, remove the oil galley plug above the ignition points, and using whatever works best for you, pump as much oil in as you can, and replace the plug. 

Then remove the #4 inlet valve inspection cover, and pump lots of oil in there, too. Now take the spark plugs out to reduce the effort, and kick/spin your engine over until your light goes off.

Even better, get a mechanical oil pressure gauge that permanently fills the place where the oil galley plug was, and never trust a 40 year old oil pressure switch. Cheers, Terry. ;D
I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline CycleRanger

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Re: Something isn't right
« Reply #5 on: May 01, 2016, 09:00:22 PM »
Yeah, good call Terry.
Replace those o-rings on those plugs while you're there.
Do you have a copy of the Honda Shop Manual or Parts List for your bike? Get one here:
https://www.honda4fun.com/materiale/documentazione-tecnica
CB750K5        '79 XL250s     CL350K3
CB750K3        '76 XS650      '76 CJ360T

Offline el pachuco

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Re: Something isn't right
« Reply #6 on: May 01, 2016, 09:48:06 PM »
I poured 1 1/2 Qts in the valve inspection hole and cranked on it for another 10 seconds. It did change the tank's level a bit. Then I pulled the gauge plug and there was fresh oil. So, I suppose my next step is to install carbs and a pressure gauge. Then letter rip

Offline Terry in Australia

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Re: Something isn't right
« Reply #7 on: May 01, 2016, 11:00:57 PM »
Looks good mate, check your oil level before you letter rip, you don't want to be blowing any oil seals because there's too much oil in your injun.....;D
I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline el pachuco

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Re: Something isn't right
« Reply #8 on: May 02, 2016, 08:10:40 AM »
 Resting much easier now. I removed the pressure gauge plug and bumped the starter. The slightest of starter bump floods the passage with copious amounts of oil. There is no doubt the pump is now primed and working as it should be. Thank you all for your help.

Offline Terry in Australia

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Re: Something isn't right
« Reply #9 on: May 02, 2016, 12:43:20 PM »
Good job mate, post some pics. Cheers, Terry. ;D
I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)