Topic: head gasket and clutch issues

[ILYA]

So I recently got a 1979 CB750 Limited Edition on a trade, to compliment my '78 that I am working on restoring, and while I know that this one is not a SOHC, it is still very similar, and so I decided to post here... I took it for a spin the other day and now I have a couple of questions:

-1- Apparantly, one side of the head gasket is leaking tiny ammounts of oil (you can see the gasket saturated in oil, thats it)... it also isn't the smoothest running engine, it slightly revs up and down when riding, which I also attribute to the gasket leak... One question is how bad is it to ride around with such a gasket leak? Can something inside be getting damaged in ANY way (like because of the lower compression on that side or smth similar) If it is ok to lightly use for the time being, when does become damaging to the engine??? I will not have a chance to pull the engine for a little while, but I still am johnsin' to go riding around...

Am I correct that I have to pull the engine to change the gaskets? what else is usually recommended to do at the same time since everything will be taking apart?

-2- Another issue is the clutch... It only grabs at the very end of the lever... it seems to be adjusted right, as in the cable and the bottom lever move as soon as the handle-bar lever is depressed... however, the clutch itself does not engage (or is it dis-engage?) until the last quarter of the cable movement... I am not sure if its just 75% worn, or if something is misadjusted internally... any ideas? again, if the clutch needs replaced, anything else that should be done at the same time???

Thanks in advance for your insight, guys!

[shoemanII]

re:  the slight surging and possible relationship to the gasket leak, i'd do a quick compression check to be sure.  personally, i'm thinking float heights/carb cleaning but i'm just another faceless old-timer offering free advice.   

no opinion on whether or not your bike will go Boom! when riding around.  can happen anytime.

engine has to be pulled to change the head gasket on cb's up to 1978, due to insufficient clearance between valve cover and sub-frame.  am in the middle of this myself.  after the gaskets are done, was going to install new cam chain.  partsnmore had the ones with a masterlink, but now appears they only have endless ones.  need to split the cases to install, am going to can that idea.

you clutch cable may simply need to be adjusted per the owners manual, at the end opposite the hand lever.

good luck on this,
bobp

[ILYA]

hmm, i'd like to hear how long people have riden around with leaking head gaskets until any significant damage occured... i can see the gasket saturated in oil, so i am assuming that side will have lower compression, but i will check later on to be sure... the clutch cable seems to be adjusted correctly, is there something else to adjust? oh, and whats the big deal with splitting the cases??? i was considering doing that on my 78, should i not?

[bryanj]

Youre OK till liquid oil exits the gasket then stop.
DOHC heads come off in the frame BUT camchain setup is a ballsache and you need to VERY CAREFULLY read and understand the manual
Surging is nothing to do with leak, probably secret additive (SH1T) in the carbs and as long as the clutch disengages to change gear and does not slip when engaged there is nowt wrong

[ILYA]

- so, when the oil starts dripping/sipping, then what happens? what is the potential damage???

- i wonder what can be causing the surging? the bike is supposed to have had good maintanence, but I havent checked the plugs and stuff yet... by the way, this bike has 4-into-2 exhaust (from SS???) instead of the original 4-into-4, so could that potentially affect how smooth it runs? would the carbs need to be readjusted or rejetted or something similar?

- and, in general, where do the CB clutches usually grab? it seems like it would be sooner than the last quarter... i think what you are saying, dont change the clutch till it goes out, but i am trying to understand the mechanics of this setup, and also dont want to end up damaging anything like tranny gears due to hard shifts...