Topic: HELP - how the $#%^@# do I remove a CB750K 1977 Valve Cover?

[Tim.]

I'm here with Chundy (don't ask) and we're trying to take the cylinder head off the bike - broken exhaust mounting boss.  I thought the valve cover would come off like my CB550's, but it doesn't.

What's the secret to removing the valve cover and then the cylinder head?

Thanks!  Light's fading so a quick answer would be welcomed!

[Lumbee]

...engine def has to come out of a CB750 before the valve cover will come off.  I've heard of people removing the engine bolts and letting the engine sit a little lower and removing it that way, but can't confirm...

[chundy]

Oh, tintin, we were one freakin bolt away from doing the engine drop and we backed out thinking this is rediculous.  Well is could have been a productive afternoon.  I will drop the engine tomorow, but I will need help putting it back in.  Aluminum welder here I come.

[Bobby]

Yep, that there motor gotta get out of the frame prior to removing any of the top end components.  Silly isn't it?  The CB750 is the ONLY bike I have owned that you have to pull the whole dang motor out just to replace a head gasket.

-Bobby

[chundy]

Is it possible to just loosen all bolts except the one pivot at the rear, and drop the engine forward a inch.  Or are we talking about a complete yank, for the love of God, please tell me I don't have to yank the entire engine.  If so that is just a reallt stupid design. 

[Bobby]

You can try that technique (I never had) but I still don't believe dropping an inch will much matter.  According to my Shop Manual, if you want to yank the head, the engine needs to be removed.  It's actually not that awful of a job and it gives you an opportunity to gussy up that old inline 4.

Sorry for the bad news.

-Bobby

[Tim.]

I keep telling Chundy all we need to do is cut off the top 1/3rd of the engine and make it what it should have been - a 500.

[frostypuck]

or...cut the frame pieces off, under the backbone, just below the coils. I saw one like that 6-7 years ago, but never found out why he did that. Obviously it was to facilitate removing the head, but anyone that has to remove/replace the head that much doesn't need to be modifying frames.
Chris in Boston

[Tim.]

Well, wouldn't it be fun if we got the valve cover off only to find we couldn't get the cylinder head off without removing the engine.

I'd imagine there's enough room above the studs to allow for this - can anyone confirm 100% on these different ideas?

So far we're at:

1) remove enough engine mounts (and don't forget the airbox mount to the frame) to allow engine to tilt forward and down allowing valve cover to clear valves and cam chain

2) hopefully there's enough room once the cover is removed to remove the cylinder head as well

Perhaps chum Chundy could take a pic of the reason we're doing all this in the first place .  If repairs could be made without removing the cylinder head, we'd avoid all this hassle, as compression and valves all seem good.

[frostypuck]

Remove the motor. It's easier than the other suggestions. Really. Especially since there's 2 of you. Just remember, drain the oil, after all the bolts are out, turn the whole bike over onto it's side, and lift the frame et al off the motor. Then just sit it somewhere with a block of wood under the oil filter cover to keep it from being too tippy.
Later,
Chris
Oh yeah, and in the words of the immortal Mr. Clymer..."installation is the reverse of removal" That slays me every time I read it. I needed a $22 book to tell me THAT!?!?!?

[cben750f0]

sorry to rain on the parade, but engine has to come out.... even when you want to retension the head after a 100km .. you have to take the motor out of the frame!!... its a pain , but one tht cant be avoided, i figured if by now noone can tell me that it can be done... it cant... sorry peace(pleace make me wrong )

[Terry in Australia]

 Yeah, all of the above Tim, rip the engine out. I've never re-torqued the head after 100 km though Ben, I just torque it down to 20 ft lbs, then leave it overnight and re-torque it in the morning, and I've never had a leaking head gasket. Cheers, Terry.

[chundy]

Thanks, a tonne.  As always this site, and it's members are very helpful, as well as humorous.  I will be draining her, dropping her (softly), and getting her apart.  I truly needed an excuse to clean the motor, replace some gaskets and oil seals.  Just as a side note, and funny one, the picture I am using came from an article that I found while googling my predictiment.  A guy racing a 750 lost a piece of his tach cable in the head and it basically shredded the inside of the entire valve train before the bike stopped.  So an oldimer came to hie rescue with this old bike that had been sitting in a field for 8 years with stuff growing in it.  They to needed to found themselves in my situation, however rather then taking the motor out, the just hacked the frame to bits.  Good times.  I'll be sure to take some pics and post em up.  If nothing else it should be funny, me with my back blown out from wrestling this bad boy onto 4X4's.  TinTin, leave your mobile on in case I fall and can't get up.
thanks again all.
PS here is the link to the mentioned article
 http://www.motorcyclistonline.com/flashback/122_9704_cardiac/

[carsholduptraffic]

all i can add is that the motor is 80kg. and getting it back in is as much of a bastard as getting it out. watch your fingers. about a 3 beer job.

[cben750f0]

rap some rags round the frame, protect you and the frame...peace

[mrbreeze]

Well you know what Larry (the Cable Guy) says....GITTTERRR DONE!!!!! ........But Hey Now..... Lets not go whackin' into a perfectly good frame to change a gasket.What are you going to do? Go get a new a frame every time you need to work on the top end? Like The other posters said....When your top end is off...do as much as possible.Mine runs good now but if I had to have it off....It sure would make it easier to polish the aluminum valve cover! Hope you do it right and get it back on the road though!......MRBREEZE ....ps(GITTTERRRR DONE)

[Lumbee]

...yep the 750 mill is about 2 bills.  I heard a guy say he has removed and put the motor back in by himself.  I call BS...what do you guys think?

[kghost]

Well that guy I would not want to meet in a dark alley.

Hey, I'm 6'3'' and about 230lb. Been lifting heavy thinks all my life. Not a light weight. I can lift one but stick it in the frame? No way I could do that without mangling the paint or worse.

[Gordon]

...yep the 750 mill is about 2 bills.  I heard a guy say he has removed and put the motor back in by himself.  I call BS...what do you guys think?

Well, I'm 5' 7" and about 140lbs soaking wet, and I did it by myself.  It required a complicated system involving a floor jack, a scissors jack, an empty milk crate and a block of wood, plus several shop rags to protect the frame.  So, in conclusion, it is possible, but not fun. 

[Geeto67]

A good trick taught to me by the hondachopper guys for when you are by yourself and need to pull the engine is to put the bike down on it's side (on top of some heavy duty blankets) then undoing the engine bolts and sliding the frame off the other side of the engine (it will still be heavy but not as much as the motor). I have tried this trick and it works, only I tilted the engine on to a rolling cart (on its right side) which got it up a few feet off the floor so I didn't have to tilt it as much. Just go slow and you'll get everything sorted out. To put the engine back in the frame you do the same thing in reverse, put it back on its side and slip the frame over it, bolt it in place and stand the bike up.

[kghost]

Yeah, I've done that trick with bare frames. Just can't pick up the engine and stick it in without block and tackle

[Terry in Australia]

Ahh you're such a bunch of girls! To remove the engine I just pick the bike up and shake that sucker right out, (I've found it pretty easy if you first remove the tank and exhaust and loosen all the engine mounting bolts, but don't tell my bro's, or they'll all laff at me) and to reinstall the engine I need to be extra careful, so as not to scratch the paint I use BOTH hands to lift it, ha ha! Cheers, Terry.

[Tim.]

Take the bolts out, find a tall hill, and you're done.

[smithrelo]

Terry in Australia!!!   I take offense - GIRLS would never do this.  

We buy 550's so we don't have to do all this macho "take the motor out" stuff...hahaha.

Anyway, I think this post cured me of ever wanting a 750, as I am the handy, dandy mechanical person in this marriage and I don't think I want to pull engines...ever!

Linda

[Terry in Australia]

Terry in Australia!!!   I take offense - GIRLS would never do this.  
Linda

Linda, my apologies again, I know, girls are too smart to be pulling engines out, me on the other hand, at 6'4" and 260 pounds am big enough, ugly enough, and dumb enough to do it on my own. My wife, at 120 pounds and 5'2", would rather "supervise", ha ha! Cheers, Terry.