Valve Seal replacement

Well, I'm getting up the nerve to tackle replacing my valve seals. I already have a valve cover gasket. I still need to get a head gasket and the valve seals (need to call Z1).

Anyway, I just wanted to ask some of the folks with more experience:

What other work should I be doing while I have the head off.
Am I going to have to take the engine out to get the head off?
Do I have to take the jugs off and replace that gasket as well (read that somewhere)?

Bike is a 1980 kz1000 G1 classic with ~31,000 miles.

I have a home made valve spring compression tool my dad welded up for me. I have been reading the other thread about trying to remove the valve springs without taking the head out, but it doesn't seem to address these questions.

thanks.

Dale

with 30,000 miles onthe clock id suggest pulling the jugs and checking pistons and bores also.ifeverything checks out id do a hone and ring job while youre in there.ive seen more than 1 motor with a new valve job that finished off the old tired rings from new found sealing in combustion chamber ! id do the usual ,guides and seals and a good valve job while its apart and a timing chain and related stuff .then you can ride another 30,000 without worrying about motorB)

At minimum, lap the valves.

You don't have to pull the engine to get the head off.

After the head is off: you can rotate the pistons down and measure cylinder wear with an inside micrometer. Measure the top of the cylinder (where the rings can't reach) and a couple of inches down where it would have wear.

I doubt you need a ring job at 30k, but it's easy to measure.

If you're going to measure the cylinder, measure it front to rear as that's where it wears.
The majority of the wear will be on the front of the cylinder (on the twins, the rear of the cylinder will wear), and that's also where you'll see the worst scoring on the piston (if you see any).

On the fours, the front is the thrust face, on the twins it's the rear.

I would agree to check everything while you have it apart, no sense in having to go back into it after a few miles, fix it right the first time,

Just another question (right now).

I understand most of what you suggested, but why do you need to hone the cylinders when you replace the rings?

does it have to do with creating a better pressure seal?

makes it easier for the rings to seat themselves with the rough surface

If you've got the head off, you for darn sure should pull the block off and replace the base gasket. It WILL leak if it's the original gasket or hasn't been replaced in 10 years or so. Trust me on this.
All the other posters are absolutely correct about checking for ring wear and cylinder ovality as well as valve stem wear, guide wear etc etc.
If you've gone this far (pulling the head off) you'd be absolutely foolish not to check everything out thoroughly.
Replace/fix what needs to be replaced/fixed if it measures
at or close to the limits....and replace the cam chain on general principles.
If you're planning on keeping the bike for the forseeable future, anything less is false economy.....especially if it's a daily rider.
My .02....

Just get a top end gasket kit from Z1. It has everything you will need except the base gasket. If there is no indication of oil leaking from the base gasket, I would leave it alone. An original base gasket is a major PITA to remove. However, when you remove the head, the cylinders may lift up with the head which means you will need to change the base gasket....chris3

the reason for the honing, it deglazes the cyl and the cross hatch pattern is needed to allow the new rings to seat,or seal, if you dont do this, you will burn oil big time

There is some good advise in this thread but if I were contemplating this work, I would either do EVERYTHING that can be done or just do the valve stem oil seals. If you do the valve stem oil seals, i suggest you check compression first. If compression is within service spec, just pull the head, disassemble, change the seals and do some clean up with a wire brush wheel on a drill or Dremel tool. Carefully inspect your plug thread holes and repair while the head is off, if needed. That is about ALL I would do. I wouldn't pull the cylinder if the compression is good.

If I did EVERYTHING, I would remove the cylinder and measure the piston to bore clearance. You will need T bore gauges and a digital caliper and you make NINE measurements... at three depths and three angles to determine if the bores are round or have ovalled.

If you have oval bores or the piston to bore clearance is out of spec, you will need oversized pistons and a re-bore/hone. If the cylinder bores are round and within spec, re-ring/hone.

I would replace ALL the cam chain stuff at this point... rollers/guides and idler assembly and the chain itself.

I would consider sending the head off for new guides and a valve job (which would include new seals and cleaning).

You can see that the valve seal replacement itself will cost only a few bucks and a couple hours where the full top end rebuild could get expensive but would completely renew the top end of your engine. The cost can't be easily estimated until you get into the engine because a re-ring/hone will cost $100 while the new pistons and re-boring job will cost quite a bit more...

Once again, thanks to everyone for their comments. I have done a compression check and all cylinders are between 145 and 155, (checked cold) so that is not really an issue.

I'll have to think about what I have time and money for at this point. I don't really ride it hard enough to put it under a lot of stress and I need to be able to ride it as long as possible this year because my son started driving and it's a lot more convenient to let him drive one of our cars to school, but that means I'm on 2 wheels so my wife can have the other car.

I'll think about it and let you all know how it turns out.

Thanks again.