Cb750 cam chain noise

The Calvary is here your in good hands now...

Engine is cold and no I forgot to test with throttle open, choke was open. Will redo test and update everyone with new numbers shortly.

Carbs have been rejetted to fit 4-1 exhaust with cycle x slip on cone muffler and velocity stacks with screen no foam filter. 80 pilots and 122.5 1,4 cylinders 2,3 have 125 mains

Carbs are all in sync using motion pro Mercury manometer.

Everything was great until I adjusted cam chain tension due to it being very noisy. That's when oil started spraying out of exhaust. I followed the Manuel loosened front cam chain nut while running at idle and retightened did same procedure on rear two nuts.

So I don't know from doing that would cause this Monstrosity.

Using the lighter oil wouldn't cause this would it?

Well here they are everyone, shit is all over the place.

Compression check was on a cold bike, choke open and full throttle and ran off starter motor. :'(

As far as valve check, did each cyclinder with lobes facing away from each other.

With those specs wouldn't that mean the valves are opening to far and allowing oil to pass through, or possible carbon build up on valve seats?

I'm going crazy, think I bought someone's else mistake.

The only way oil is getting into your cylinders via the valves is through worn out stem seals and valve guides. If you have unburned oil coming out your exhaust, chances are strong you need to do a valve job / new seals. Bottom line is on a 40 year old bike, anything rubber is suspect, especially if it hasn't been run regularly to keep the rubber pliable with oil.

Low mileage is not always a good thing on an old bike.

The compression results could easily be caused by leaky valves. Only way to know 100% is to do a proper leak-down test to see where you have leaks.

Otherwise, get the head off, have a valve job done with new seals and put it back on. A new head gasket and time is all you lose by doing that, if it turns out you need to get into the engine for a top-end rebuild (new rings / hone minimum).

Compression even cold is still low or not correct. the valve shim .13mm is fat and .06mm is tight so for the most part your running loose on all but #4 I cant help but think if you had it running good with no oil before the pipe and carb mods then the cam chain adjustment that the rings are fine and you just need to dial things back in, first off Get the valve shims dialed in but don't push the tight side of 0.08mm... Do a static timing chain adjustment per the manual, not a running adjustment.

Or what Tim said... You could do a rude leak down with the compression tester if its a quick disconnect type with a shrader valve, if it's as bad as you say that air will make noise under the valve cover and run down fairly fast.

Ok my question now is how to do a leak down test, that is new to me. Is there another forum explaining this

Blacklisted_kolasa said:

Ok my question now is how to do a leak down test, that is new to me. Is there another forum explaining this

Click to expand...

Basically the same as the compression test but takes more time... you need to be TDC compression stroke each cylinder add air to the cylinder via plug hole I just use 100psi for reference should hold for 5 minutes to 90psi to pass. This is a very rude test method not any NHRA or F1 shit so basically if you are watching the gquge drop it failed, if it holds 100-89 its decent. you may be able to get a tester on loan also or the cheap ones are idk 50-100 bucks but I would just spend the money and get the top end done.

I have a 82 750 nighthawk motor with no electrical, will this swap into my fram no problem and use all same electrical component ?

I know all cb 79 to 83 are just not sure about the night Hawks

I know this thing has good compression and valves, just not sure about the electrical and mounting.

Just seems like the easier route to go and whole lot cheaper. Then I can always put this motor on the back burner.

Not sure of the motor mounts on the 82, I know the cases changed by then, no kick start added an oil cooler some other things... you might to a search for "CB750 1979-1982 motor swap" and read up on what shows up.