Top End Rebuild, need advice.

Okay, so my engine was leaking a lot of oil at the top end gaskets and tach drive gear, so i just decided to take the engine off the frame and replace the gaskets.


After reading my service manual a few times, and reading some posts on top end rebuilds on here, i'm feeling a bit intimidated by all that is involved.


I thought i could only buy the gaskets, tear the top end apart, replace gaskets, and torque back to specs. but i guess there's a lot more involved.


So from what i've read, i should check my pistons and rings while im in there and valve clearance. Is there anything else to look out for?


What if i just replace the gaskets/o-rings, slap and torque all that back together? Is it going to help any, be worse, or should i just rebuild the whole thing if im gonna bother opening it up?


I'm a bit sketched out because it's my only motorcycle, and it runs decent, i'm just loosing a lot of oil. i wouldn't want to run into more trouble (and extra $$$) taking it apart... as they say, if it works, dont fix it.

Its not hard to tear down and reassemble, but it ends up costing more then you think.

I tore mine down just for the hell of it and am now regretting it, should have done more testing first (my threads right below yours)

Its not that bad I actually enjoy doing it quite a bit. It also depends what model motorcycle you have and how many cylinders there are the check.
While your in there though you might as well check everything to name a few scored piston, scored cylinders, valve clearance, valve seals, wear on the cam, cam chain. chances are if it runs most of this stuff is fine. But you could narrow down the oil problem before tearing it apart, is the oil physically leaking out of the engine? or is it burning it?

yes, i've been following your thread and it's giving me second thoughts about starting the engine teardown ???


i know how to wrench things and i can definitely read instructions, but i've never opened and engine before.


As I've read on your thread, I was thinking bout the initial testing before tearing everything down but my engine works decent and it *SEEMS* like i have proper compression etc... It idles OKAY, starts on first kick after its warmed up. So really, besides squirting oil through the tach gear and some seepage through the top end gaskets, its fine and i 'd drive it around like that until i get some greenbacks to do a proper job on it. But it's a pain in the ass to keep clean and i always have to be on the lookout to make sure i don't run out of oil, specially on a long ride.


I would definitely not just tear it down for the "hell of it", it seems like a pretty big and costly job ;D


I guess the big question is: can i just change the gaskets and do the rest later, or is it going to hurt anything?


I know there are things i *SHOULD* do while i'm in there, but is it going to make it run any worse if i just change the gaskets and tear it down another time to rebuild/adjust the whole top end? I wouldnt be opening it at all if it wouldn't be for the oil mess and the paranoia of running out of oil or breaking something cause of improper lubing due to lack of oil.

foundation982 said:

But you could narrow down the oil problem before tearing it apart, is the oil physically leaking out of the engine? or is it burning it?

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It definitely leaks out of the engine through a few spots as you can see on this picture:

head cover gasket all around, head gasket on the right, and i think the base gasket is fine, but i'd probably change it too while i'm in there.


I dont think the bike is burning much oil if any as it is not smoking under normal running condition. ( it only does when the choke is on for some reason, my choke wont work properly and seems all f*&%ed up but that's for another topic.)


Oh and the bike is a 78 zuki GS750, should've said so, my bad.

try re-torque'ing everything 1st

Swapmeet Louie said:

try re-torque'ing everything 1st

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i was scared i had to since the engine is out, but i guess it would be the smart thing to do before investing and trying anything else.


is there a way of doing the top end job without removing the engine out of the frame?. my manual says it has to be taken out, and a friend of mine that worked on his old KZ 650 also said you cant pull out the head from the studs without the frame backbone interfering.


Definitely don't want to skip steps, but also not the kind of guy that likes to work for no reason ;D

Ratabilly said:

i was scared i had to since the engine is out, but i guess it would be the smart thing to do before investing and trying anything else.


is there a way of doing the top end job without removing the engine out of the frame?. my manual says it has to be taken out, and a friend of mine that worked on his old KZ 650 also said you cant pull out the head from the studs without the frame backbone interfering.


Definitely don't want to skip steps, but also not the kind of guy that likes to work for no reason ;D

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some bikes you can some bikes you can't depends on how the frame/engine is setup you should be able to judge if you can or not by looking at the clearance between the back bone and the engine head but my guess would be you can't. yeah it sucks getting engines in and out of frames multiple times, my cl350 is the biggest pain in the ass

I believe you can remove the cam covers and retorque everything though...? (while in the frame)

Swapmeet Louie said:

I believe you can remove the cam covers and retorque everything though...? (while in the frame)

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definitely, but the engine is out of the frame NOW. I have to put it back in to start it and and see if it still leaks, and if it does, looks like i'll have to take it out again :


ah well, you live you learn i guess.

ho-humm...

Advice thread is a little late.

Been there.

It's easier to work on the motor when it's on the bench although it is overkill for checking the torque.

GS motor you can do the complete top end in the frame.
It's easier to work on IN the frame as the motor doesn't roll around when your torquing stuff
You may not have to do base gasket as they 'glue down' really tight (if cylinder moves you will have to do it.
The oil leaks are probably 'o' rings around studs oil feed to cam, valve cover gasket is 'normal' when gasket wasn't changed at service
It's a pretty expensive gasket if I remember right? (haven't done for about 20 +yrs )
That is the easiest motor in the world to do a valve adjustment on, easier than screw and lock nut (just more expensive when you need to change shims)