Topic: 1982 cb 650 sc nighthawk valve question

[WFO]

Ok i replace a leaky gasket the one under the rocker arm assembly i put everything back together and adjust the valves (per the manual) checking twice i put the valve covers back on and fired her up ( she starts) only the 3 or the 4 cylinder valves are clacking like crazy so i shut her down and pulled the valve covers and checked the valve adjustments and they are spot on.

So i fire her up again and they are clacking away and prior to me replacing this gasket she ran like a sewing machine very little valve noise if any at all, my question is what could cause this new clacking and should it go away with a few miles on the total re adjustment?

[speedy gonzalais]

thats strange you say you fixed the gasket is the cam sitting flush on the head?

[WFO]

thats strange you say you fixed the gasket is the cam sitting flush on the head?

It better be i never removed the cam chain lol.

[speedy gonzalais]

ok is the rocker assembly sitting flush

[WFO]

ok is the rocker assembly sitting flush

Yep i checked that while i followed the torque proceedure per the manual it was like 21 screws it went on nicely.

[speedy gonzalais]

is the clacking continuous the only thing i can think of is maybe one of the valves is sticking other than that you may have set the tappets wrong and one last thing, is oil getting to that part of the cam?

[WFO]

is the clacking continuous the only thing i can think of is maybe one of the valves is sticking other than that you may have set the tappets wrong and one last thing, is oil getting to that part of the cam?

Ya i pulled the covers right away to see it oil was getting up top and it is and i went throught the tappet proceedure twice to make sure, the thing is the settings are .002 and .003 so there isn't a whole lot of difference but the sticky tappet could be it but i hate to think i have to take it apart again. 

[speedy gonzalais]

just pull the covers off crank the engine slowly untill all the valves have opened and closed do it a couple of times any sticky valves wont return till the piston comes back up, ur spot on with the gaps .002 in .003 out the engine needs to cold but u prob know that already. And are you putting the fila gauges between the camshaft and rockers ?

[WFO]

I will try to mess with it during football today and yes i used a feeler gauge.

[speedy gonzalais]

what i ment was are u putting it between the cam shaft and rockers also are u using a ring spanner and screw driver?

[Soos]

You might want to run with a higher exhaust clearance.

I do, and feel no loss in power. Can't remember the post on it, but it has to do with a common problem the '77/'78cb750 and all the SOHCcb650's share.

The valves if any that burn, are the exhaust valves, and the extra closed time with the extra clearance helps with that problem.

And as for clacking, I have noticed EVERY time I removed a head, and re-installed it, I get a bit of clacking of the valves.
It always went away in 50-100 miles.
I'm guessing from minor mis-alignment and it just takes time for the "new" positioning of the rockers takes a bit of time to wear in where it runs smoothly.

The only other thing to think of, are you 100% sure you didn't drop something in the head area?


l8r

[WFO]

Ok got it figured out the problem was with the shop manuals instructions as to where to set the timing mark to begin the tappet adjustment, per the manual it leaves the slide going up the lobe so when i set it when it cam around it had a little play ( clacking ). So i just placed the slide on the duration end and set it so it keeps that slide on the cam iam not sure what was going on or what i was doing wrong other than following the instructions to the letter i also turned it around another 360 and it still wouldn't line up correctly,ohhhhhh well it's back to running again and i got to try out my new sync gauge i didn't even have to adjust the carbs at all and the oil leak is finally gone ( i hate leaks).

The engine on this bike is suprisingly tight the previous PO took great care of it and iam continuing that and soos by running the exhaust clearence higher you mean use a smaller gauge?

[Soos]

Use clearances of 0.004 to 0.005 instead of 0.002-0.003 the book calls for.
So a thicker feeler gauge.

here are references to what hondaman is talking about with the extra valve clearance on the exhaust side.
good reading IMO.
http://forums.sohc4.net/index.php?topic=10543.0
And the many a times quoted post by hondaman himself.
It's worth reading the whole thing, as well as logs kept by a ex-honda tech showing a late 750 and a 650Z he had to fix the exhaust valves (the guides?) on.
http://forums.sohc4.net/index.php?topic=10540.0

l8r

[WFO]

Use clearances of 0.004 to 0.005 instead of 0.002-0.003 the book calls for.
So a thicker feeler gauge.

here are references to what hondaman is talking about with the extra valve clearance on the exhaust side.
good reading IMO.
http://forums.sohc4.net/index.php?topic=10543.0
And the many a times quoted post by hondaman himself.
It's worth reading the whole thing, as well as logs kept by a ex-honda tech showing a late 750 and a 650Z he had to fix the exhaust valves (the guides?) on.
http://forums.sohc4.net/index.php?topic=10540.0

l8r

Thanks soos i will look into it.


EDIT: damn that was a great read and i really like hondmans explaination very indepth, iam going to do it since iam very good at adjusting valves now  and i love the idea of my bike lasting longer.

[crazypj]

So, you did adjustment with crank 180 degrees out and valves on overlap?
PJ

[WFO]

The manual said:

Rotate the crankshaft clockwise and align the 1.4 T mark with the index mark. Make sure the number 1 piston is at TDC of the compression stroke ( both #1 rocker arms should have free play)

Measure the valve clearance yada yada yada


Recheck the valve clearance

Rotate the crankshaft ( 360 degrees) clockwise and align the 1.4 T mark with the index mark


adjust valves

[WFO]

So, you did adjustment with crank 180 degrees out and valves on overlap?
PJ

no..

[speedy gonzalais]

it sounds to me like u adjusted the wrong rockers

[WFO]

it sounds to me like u adjusted the wrong rockers

it runs great the manual shows which valves to adjust per crank rotation maybe i didn't explain what i did well enough.

[crazypj]

You watch intake rocker, it goes down, it comes up, you hit tdcc 1.4 and do either
cyl 1 intake&ex
cyl 2 ex
cyl 3 int
 OR
cyl 4 int&ex
cyl 3 ex
cyl 2 int
NB,
 TDCC=top dead center compression
 Still sounds like you did them on overlap, easily done when you follow manual too close
PJ