Topic: Cant get valve cover back on

[crazypj]

Depending on actual model and engine capacity, thats a completely different animal.
The hydraulic tappets work well as long as they get clean oil of correct viscosity but dirty oil  or dirt in motor  almost instantly trashes them in my experience. Honda used Hydraulics on DOHC 550 and 750's, I'm not a fan of either

[Remcod]

Yes my cbx also has them. This because the topic starter says it’s a 82 nighthawk

[DaveBarbier]

No, the '82 650 is a SOHC4 just like our other bikes with regular tappets and rockers riding on the cam.

Only different thing is the way you measure valve clearance. That's measured between the cam lobe and the rocker face instead of the tappet and top of the valve stem.

[juntjoo]

thanks for all the info. So I did the rubber band thing(is it correct?), tho I've no clue how these rubber bands will combat the mysterious force that's keeping this cover down, but it's still not completely flush. I must have misunderstood their purpose. I'm at TDC. BTW, is that on the T or in between the T and the F?

So I'm guessing either I warped the cover taking it off by incorrect bolt pattern or or they just warp naturally over 35+ years or they're supposed to fit with some spring tension.

what should I do next? Tighten down slowly? I'll wait for confirmation on this and work on something else...

[TwoTired]

I'm no 650 expert.  But your pics show the tappet adjusters all the way in rather than all the way out.   Wouldn't this force all the valves to open as you are installed the cover?  You'd be fighting the valve spring forces to do this.

However, more risky, is if one or more adjusters were lined up on the side of the valve stem instead of directly on top.  Then as you tighten the cover down the adjusters place side pressure on the valve stem (They are not vertical but the cover goes down vertical) and the stems bend rather than open into the chamber.  That is an expensive lesson on maintenance procedures for this bike.  (Replacing valves and valve guides)  Bent valve stems prevent or retard valve closure and lead to loss of compression.

The CB500/550 manual has a service warning about this.


Good luck!

[juntjoo]

Remove valve cover.
 Remove tappet covers.
 Loosen lock nuts on adjusters and back them out a good bit.
 Use rubber bands on each set of rockers to hold them up. #1 intake to #1 exhaust. The rubber band will lift up on the rockers. Repeat for other three. Have all four sets held up.
 Set #1 piston at TDC, just to ease in initial valve adjustment. Confirm that the notch on the end of the cam is correct.
 Install valve cover. You may have to tap *LIGHTLY* with a rubber hammer to seat it on the locating dowels.
 Install screws/bolts and torque correctly.
 Remove rubber bands.
 Tighten the adjusters by hand until they're loose on the cam lobes.
 Adjust first 4 rockers.
Rotate engine and adjust next 4.
 Rotate engine again and double check your work.

am I lifting the rockers where they meet the lobes or the or valve stems?

[strynboen]

at the valve stems..it only there it can give problems

(think the Photo vas give a falce idea..)

[juntjoo]

my brain still can't figure out though how this force of rubber bands is going to counteract any force that's keeping this cover off the head. they're free to move upwards where the lobes are pointed up and contact them. I'm wondering if this trick is for a different cylinder head.

[juntjoo]

at the valve stems..it only there it can give problems

(think the Photo vas give a falce idea..)

Okay, thanks.

Okay, I'm gonna do it. fingers crossed. it's all on you guys. I'm not to blame. if I destroy my valves expect a bill! wish me luck!

[strynboen]

the rubber bands do nothing to the cover..it holds the rockers so they not kolodides vith the valve stems...så you vill not feel any differences..,,but the valvet vil not be bend..

[DaveBarbier]

We think the reason that your cover isn't going down all the way is because the tappets (the screws that are screwed into the rocker that touch the top of the valve) are hitting the valves at an angle. The rubber bands just hold the rockers up away from the valve tips.

Also, the cover will not sit flush when you just place it on the head. Spring pressure holds it up. You need to screw it down. AS LONG AS THE TAPPETS ARE NOT HITTING THE VALVES LIKE THE PICTURE TWOTIRED POSTED.

TDC for 1&4 is when the T hash mark lines up with the stationary mark on the engine case.

[juntjoo]

the rubber bands do nothing to the cover..it holds the rockers so they not kolodides vith the valve stems...så you vill not feel any differences..,,but the valvet vil not be bend..

thanks. okay, what do you think? should I tighten down the bolts? Am I in TDC? As you can see there is more than a millimeter there.  doesn't look like warpage as each side, front and back have equal space(separately) so it's just tilted really. Adjusting nuts out. Rubber bands holding tappets off valves(or not since we have a gap? ).

TDC? https://imgur.com/a/BM0TX

valve cover gap https://imgur.com/a/ky4Io

[juntjoo]

oh never mind! figured out it was the adjusting screws that needed to be backed out.  I was just loosening the nuts not understanding how they worked. oops. excuse the noob lol.

thanks again for all the help.

[juntjoo]

I do gotta ask tho, since we're dealing with hundredths of an inch with the valve cleatances, how do you exactly get TDC?
is it just that area where the pistons rest? or right over T or right next to it in between the T and F? Im going to guess there is a range of about a half inch where the valves hold themselves right? 

[juntjoo]

We think the reason that your cover isn't going down all the way is because the tappets (the screws that are screwed into the rocker that touch the top of the valve) are hitting the valves at an angle. The rubber bands just hold the rockers up away from the valve tips.

Also, the cover will not sit flush when you just place it on the head. Spring pressure holds it up. You need to screw it down. AS LONG AS THE TAPPETS ARE NOT HITTING THE VALVES LIKE THE PICTURE TWOTIRED POSTED.

TDC for 1&4 is when the T hash mark lines up with the stationary mark on the engine case.

thank you. just got your message. okay i didn't see that mark above the T. and as I just mentioned I figured out exactly how the whole mechanism works and backed the screws out, not just the nuts. this weeknwas the 1st time I ever dealt with these adjusting screw/nut pairs, in the valves and carburetor sync screws. humans can be pretty smart.

ps. the cover sits flush with screws totally backed out