Here's One For The Gurus.....

Has anyone on here ever replaced the valve stem seals on a KZ650/750 WITHOUT removing the head ???
I've done this on rocker arm type engines but I've never had to try it on a shim and bucket type engine. I know the valves sit down in the head quite a ways making it very difficult to get at the springs and keepers.
My very low mileage 650 has some of the inlet valve stem seals starting to go bad from old age and they are letting some oil go down the guides on the intakes, especially at highway speeds when I back off on the throttle suddenly. I don't want the intake valve stems and poppet tops getting all gunked up if I can prevent it.
Ideas anyone ?? Actual experience ?? Special tool(s) required ??
All contributions gratefully accepted.

Rick, I looked at this several years ago,I never did figure a way to get them off and back on without damaging the new seals.
the big issue was no room to work with the motor in the bike.
after looking at it for quite some time I just pulled the head and did a valve job, in the end it was worth it

I think one of the issues would be,compressing the springs again to get the keepers back into place?:blink:

I've never tried this,but I read(or heard)about someone stuffing the cylinder with thin rope,and then rotating that piston up,to keep the valve in place.
I HAVE done that on a 2-stroke engine,to keep it from turning over,while pulling the clutch off(snowmobile).

I don't know Rick...unless there's a safe way to reinstall the keepers,I'd just pull the head.You're going to be almost half way there anyways,aren't you?
If need be,I've got the proper spring-compressor,I could lend you.

Sandy, I figured a way to remove the springs, had a piece of tubing that had slots in it and a U shaped rod that went into the cam journels, it had a threaded rod and two nuts on it, you could wrench it down to change the springs, but it was way tight.
the valave would be held up by putting air in the cyl.

we did use this set up on a drag bike to change out the springs, but I never could figure out how to get in there to replace the seals

ive changed plenty of chevy valvesprings and seals over the years by pumping cylinder full of air and pulling them apart but everything is exposed on a v8 head.on a motorcycle head if it has enough miles to need seals it wouldnt hurt to check guides and have the seats and valves cleaned up anyway,id say pull the head.

i have to ask why any body would even want to do that it sounds like a good time to pull the top -end apart you must want to change the valve seals for a reason probably excess oil consumption it might just be a good time to do it the right way. if you could make up a tool that would fit down in the bucket bore how would you be able remove the springs and retainers with out chewing up the bucket bores. you must already have the cams out so pull the 12 headnuts and do it the right way . check the guides out and get the valve job done at the same time. this is important stuff so don't cut corners trying to save a penny.

Thanks for all the suggestions, gents, although some of you have apparently misunderstood my situation.
My 650 has ONLY ~4,000 miles TOTAL on the clock, soooo....
the valves and guides are fine and so is everything else.....except that the stem seals have probably died of old age. I do NOT want to pull the head unless absolutely necessary because then, honestly, a guy should pull the block and replace the base gasket at the same time. If you don't replace that old base gasket it is pretty much guaranteed to start leaking when you put everything back together. Keep in mind that the head and base gaskets are 30 years old. They don't leak now....and I want to keep 'em that way.
Back to my original problem: Sandy and BSKZ650 are on the right track. I've done the "Indian Rope Trick" before, Sandy, but pumping the cylinder up with 100 PSI air works a lot better. The big trick, I believe, is as BSKZ650 says with the specially designed tool to fit in the lifter pocket AND still leave some room to get the keepers out when the springs are depressed far enough. I need to have a good look at a naked 650 head and do some serious thinking on this.
Fortunately we have a lathe, MIG welder and other nice things at work for making special tools....and the boss is a machinist and also a pretty decent welder. This will be a good winter project methinks. If it all works out, there will be many pics taken for the education of all who might be interested.

Rick,

Back in the day, BMW sold a tool that let a tech change valve seals on the origional 2 valve K bikes. Using it involved removing the cams and bolting the tool in the place of cam bearing caps. As I remember from the service school, it used a threaded rod and adapter to compress the spring enough to get the keepers out and back in. After the spring came out a trick pair of pliers were used to pull the seal out. The tool was about $600 in 1985.

Good Luck,
Jon

Thank you for that, Jon. That's exactly the kind of info I need. It'll be an interesting tool to actually make....and then actually use. There will probably be some mods required but then that's the way of homebrew special tools.....
Design, build, use, modify, use....etc, etc.
Hopefully I won't need the special pliers because the hardest thing will be removing/installing the little circlip
that holds the seal in place. Cutting the old seal off SHOULD be fairly easy.....and pushing the new seal on SHOULD be fairly easy too. It's that darn circlip that will be the killer. Well, we'll see....

how about some of that high mileage motor oil thats supposed to swell seals up inolder motors?

Well, Plummen, to my mind stuff like that falls into the "overhaul in a can" school of thought.....but I know you're kidding me cuz you're smarter than that....right ??
Nope, this kind of thing has to be done properly. Anything less is just a bandaid, IMO, so I'll just have to buckle down and get 'er done. Should be an interesting process.
Film at 11.....or as soon as available....hopefully sometime in mid-November or thereabouts....

in the same time you fellas design and build a tool that may or may not work - more than once.

I could have:
the head off
de-carbon comb chambers
check all 8 guides remove bad ones replace and ream to size
de-carbon- clean-grind valves
grind seats
lap in final sealing surface
check seat pressures reinstall valves
replace 8 NEW seals
set valve lash
check deck for flat
wash and dry
drink beer.

reassembly is another half day. but never the same day(for me)


heating up the oven is the pain (smokes up the garage)

I know I have made it sound too easy but really the hardest part is buying /having the right tools and courage to break into your baby.
roller engines do not require a sterile clean surgery room as do plain bearing engines. Roller engines are very forgiving and filter the oil so well.

BESIDES KAWASAKI WOULD HAVE MADE THAT TOOL AND SOLD IT TO DEALERSHIPS IF IT WERE OF ANY VALUE TO THEIR PRODUCT

I spent 10 years working on Phoenix cop bikes did a lot of top ends.