Topic: 82 CB650 upper head noise

[ak58lp]

Hello. This my first post here as I didn't know this forum existed. I have just replaced a head gasket along with the 2 small O rings on my 1982 CB650 Nighthawk for an oil leak.

Everything went back together but I have the problem below. Can anyone offer some suggestions please?

After I adjusted the valves the other day I finally got the bike to start today, but the top end is very noisy. It sounds like valves or cam chain I believe as when I listen closely it’s all in the top end. Just in case I adjusted the cam chain nut again and it seems fine. Book procedure says to lossen adjuster nut, turn it over with hex end a few times then adjust nut again.

According to my book and an older online manual I found this is how it’s done.

-make sure the engine is cold

-use a spanner on the hex nut on the pulse generator assembly, turn the engine clockwise (forwards) until the extreme left cylinder #1 (shifter side) has risen to top dead center and align the “1.4 T” mark with the upper  index mark on the pulse generator. Make sure the No 1 piston is at TDC of the compression stroke. I confirmed this by taking the end spark plugs out and putting a pencil inside. Number 1 cylinder is higher than #4 or so it seems??

-Now #1 piston is now exactly at TDC and both valves are closed. Both valve clearances of No 1 cylinder can now be checked as can the inlet valve of No 3 cylinder and the exhaust valve of number 2.

-valve clearances are 0.002 in for the intake and .003 for the exhaust. Slide the feeler in and adjust the screw until you feel a slight bit of resistance. Adjust the locking nut and check again. This is a real PITA as the adjuster screw will turn with the nut when you tighten it up. I bought a deep socket and have put the screwdriver through the top holding the screw while I tighten the nut by turning the socket with a pair of channel lock pliers. Seems to work ok.

Now it says to rotate the engine one full 360 degree turn forward again and align the mark again. This should be TDC of the outermost piston number 4 (brake side).
-adjust both clearances here on #4 piston  and also the remaining valves, inlet #2 and exhaust #3.


I will double-check this again as soon as I can confirmation that this is correct.

-Do pistons 1 and 4 fire together and if so why is another full turn of the engine needed to check number 4 on it’s own.   

-Does it sound like I am doing this right? Also is piston number 4 the far left one and followed by 2,3 and 4 going from the shifter side over to the brake side?

- Could this be cam chain as the bike seems to run ok just very noisy?

Thanks in advance.

[cb650]

The plug also fires on TDC of the non compresion stroke too.    Did you remove the cylinders?

[ak58lp]

The plug also fires on TDC of the non compresion stroke too.    Did you remove the cylinders?

I did not remove the cylinders but relapped the valves so I had them out. There are two nuts on the cam chain adjuster and I assume the bottom one looks after the tension on the spring? Here is a post I found that sounds just like my issue.

http://forums.sohc4.net/index.php?topic=40828.0

"I found this method in a scanned article about CB650 maintenance. I will find it and attach it for download.
I agree that this sounds weird, but... short story - not long time after adjusting valves I heard too much klackety-klack. And i though - hmm, impossible, I did the valves, so it must be camchain. I did it the "manual" way, and noise is still there. gosh, that't the valves, I think, so tank down, covers out, and measuring.... All's perfect! So what the hell? Camchain? And out of pure desperation, i thought, what the hell, I will try it - the running method. So I put bike on idle, and rattle is there, I loosen the screw... gone! rattle was gone! So that was it  - weird, but worked for me.
My take on this is  - you have nothing to lose. I mean, if you will keep it at idle nothing critical will happen, in extreme case, just shut it down and set it properly. I say it's worth a try"

[cb650]

Did you remove the nut/bolt for the adjuster?

[ak58lp]

Did you remove the nut/bolt for the adjuster?

I never had the tensioner out of the engine the whole time. The only thing I did when I put the cam chain back in was to loosen the bottom nut and push back hard on the big spring/bow for the tensioner. While holding it in place I tightened the nut which kept the spring back away from the chain. This allowed me enough slack so I could get the chain and sprocket together. 
I double checked, and triple checked that the T 1.4 was dead on with the index pointer and the notch in the cam was pointing horizontal to the front of the engine as per the book. I even took a picture of both. The first time I had it one tooth out and readjusted so the cam sprocket bolts would go in and everything stayed aligned.

I just tried the bike now and loosened the bottom adjuster nut only while the bike was idling then turned it back in. No difference. 
Does the top nut do anything for the adjuster/spring as I never adjusted it, it is just tight now.

The bike runs fine and does not miss at all so it makes me think the valves are set correct otherwise would it not sputter and backfire?

The only thing I noticed is that (I have no idea if it was like that before) that there is a bit of oil blow by on the right side top bolt that holds the rockers in place? It has an alen key hex head on it. My book says this is a small bolt that looks a bit like a carb drain screw with an O ring on it. I think I have one of these green Orings in my gasket set.

Thanks CB650.

[cb650]

I wonder if when you set it for the clearance to remove the cam if it didnt hang up.  Try pushing in on the adjuster while its loose.
Dont know what else to tell you.  Sounds like you have it all covered.   The rocker shaft is a easy fix.  turn engine so that rocker is off the cam and then you can undo the allen head and replace the o ring.

[ak58lp]

I'll give that a try next but I'm sure I heard it snap in place after I had it all together. I don't know what else to try either unless I take off the rocker cover again and inspect the cam chain, rockers etc. Don't really want to loosen the 22 bolts again.

[ak58lp]

The plug also fires on TDC of the non compresion stroke too.    Did you remove the cylinders?

Keep in mind this is also my first attempt at adjusting valves. Is there a sure fire way to make sure I am setting the valves for TDC of piston 1 and not 4?
This is what I find very confusing. The book (Haynes) says to bring cylinder 1 to TDC and make sure the index mark is correct (index mark is easy to set). Then adjust both valves and then roll it over 360 degrees. Would piston 1 and 4 not be in the same position again.




Sorry but I need a good understanding of the procedure as this may be the problem??

Please let me know if the valves are out, would I not have a sputtering bike?

[cb650]

Yes the pistons will be but not the valves.    Cam rotates 1/2 speed of crank.   At #1 TDC on the compression stroke both valves will be closed ( lobes of the cam should pointing down) next revolution when the piston is TDC the exhaust will be closing and the intake will be opening.
I'm surprised none else has replied.

[ak58lp]

Thanks CB. I will doublecheck the cam lobes tonight and verify where they are. This is one thing as I mentioned that was not clear to me. That will verify the #1 cylinder valves for me I hope.

I think we are on the right track and I really appreciate the help. It's very frustrating when all I have is a book and my limited knowledge. I have learned a lot but I just want to get the beast running.

It's my wife's bike....enough said.  

[ak58lp]

Yes the pistons will be but not the valves.    Cam rotates 1/2 speed of crank.   At #1 TDC on the compression stroke both valves will be closed ( lobes of the cam should pointing down) next revolution when the piston is TDC the exhaust will be closing and the intake will be opening.
I'm surprised none else has replied.

Well I think I figured it out CB by your plain english explanation. I brought the index timer to 1.4 T and pulled off both outer valve covers. One piston has to be at TDC right?

Sure enough both cam lobes were heading down in the motor on cylinder #1 (shifter side) and the valves had way too much free play.
Piston #4 (rear brake side) had the exhaust cam just starting to lift and both valvles there were adjusted to spec.

So it seems I had it bass akwards.

PLease verify the pics and confirm my suspicions. Then I will readjust properly tomorrow night.

Sorry not large pics.

Index marker

[ak58lp]

Cylinder 4 showing cam moving up, not TDC. These valves are tightened to spec..wrong I believe.

Next pic is cylinder #1 (shifter side) which looks like cam lobes are pointing down and this should be at TDC. These valves have lots of free play. Also wrong! So in a nutshell cylinder 1 should have both valves adjusted to spec (along with proper ones for 2 & 3), then rotate the engine 360 and #4 should be TDC. Adjust both valves on that one and then remainders on 2 & 3.

[bollingball]

I use a compression gauge screw it in #1 far left Cly. while sitting on bike.(facing forward ) turn engine over by hand slowly as soon as you see the needle start to move stop. now look at the timing mark you should not have past it yet take the slack out of the kicker and start bumping the kicker lightly with your fist until the timing mark is lined up. Now you know #1 is at TDC on COMPRESSION stroke Now you can set #1. repeat for #4 or just rotate crank 360.

[ak58lp]

Well I feel like a jackass, as I had the valve timing all wrong as noted above. I've never done them before so go figure.   
Set all valves to spec on the the right cylinders at TDC and it's so much better.

Here I thought it was cam chain or something worse all along. Thanks everyone and especially CB650 for setting me straight.