KZ750 noob engine disassembly - what work to do?

GLORY day!

I got a call from the shop today. The bump honed out. I need a new set of piston rings (original size), but that's pretty much it from here. They said they'll lap the valves, replace the valve guides and de-carbon the cylinders and possibly head?

So it sounds like I'm gonna get outta there with 3 hours of labor and some piston rings.

Does anyone have a recommendation for a good gasket sealer for these bikes? Can I go to any hardware store and get run of the mill gasket sealant from the auto department?

I'm still giddy about not needing to bore anything or replace any really expensive stuff. What a wonderful stroke of luck!

here ya go

kzrider.com/index.php?option=com_kunena&...mit=20&limitstart=80

Many thanks.

While they're doing that work I'm gonna try taking the oil pan off and seeing what I can see. I need to find that piston ring and see if I can wipe out some of the gunk that fell in when I took the block off.

Suggestions are welcome. I'll be searching the forums for the next half hour or so for tips on the best way to clean it out in there.

Edit: I found this:
kzrider.com/index.php?option=com_kunena&...ew&catid=2&id=210385

I pulled the oil pan off, gouging it pretty badly on the corner in the process (great). Now that I'm in there, I still can't find the piston ring piece. This is rapidly escalating in badness!

Here's a picture of the corner where I, like an idiot, used a steel screwdriver. It looks worse in the picture than in life, but I definitely gouged some aluminum. Do y'all think I need to replace this oil pan via ebay?

Considering the price of an oil pan gasket, I'm gonna try smoothing out the gouges and using some liquid gasket or gasket sealer or something on this chipped spot.

On the subject of the piston ring: I've really dug around in there (looking from the top and reaching in from the oil pan) and found nothing at all but dirt.

Is it a really terrible idea to put it back together and hope that, if the half piston ring is still in there, it'll settle into the pan? Is it more likely that it'll rattle around somewhere and destroy everything?

The dirt in there should just settle down and get filtered out, I assume?

my 4cyl 400 yes thats right, well it didnt come with a speedo or anything, iv got the engine into its seperate sections, i got too carried away in the moment with tools. haha

it can as a started bobber, bad i must say. how do i know the milage? the pistions look pretty clean a few bits of burny stuff but not alot and that cleans off great, any ideas?

staniel wrote:

GLORY day!

I got a call from the shop today. The bump honed out. I need a new set of piston rings (original size), but that's pretty much it from here. They said they'll lap the valves, replace the valve guides and de-carbon the cylinders and possibly head?

So it sounds like I'm gonna get outta there with 3 hours of labor and some piston rings.

Does anyone have a recommendation for a good gasket sealer for these bikes? Can I go to any hardware store and get run of the mill gasket sealant from the auto department?

I'm still giddy about not needing to bore anything or replace any really expensive stuff. What a wonderful stroke of luck!

i hate to be the bearer of bad news but once the valve guides get replaced you NEED to have valve seats reground ! as the everything is located off the guide. replace guides seats need to be reground lapping the valves after guide replacement is wasting your money. 2nd kz750 with 14,000miles or so should not need guides 900 / 1000 had more valve guide wear problems than 650 / 750 fours did. i just do not want you to be lead in the wrong direction.

DFIGPZ wrote:

i hate to be the bearer of bad news but once the valve guides get replaced you NEED to have valve seats reground !

Thank you for looking out for me! I did some thinking about this. I'm pretty sure all they're replacing is the valve seals. The mechanics at this shop are pretty sincere guys. I can't tell, though, if they're happy or mad that I took most of my engine apart and did all the easy work.

For the gouged oil pan I got some Permatex Ultra Copper gasket goo and I got some high temperature metal repair epoxy ("strength increases with heat!"). Once I get all the gaskets off, I'll clean it all out and put the repair goo on there and gently sand it smooth. (That is unless someone has a suggestion for me!)

And, finally, for the missing piston ring: I have really dug around in there. I got a telescoping magnet probe and poked it in from all angles. I peered in with a mirror-on-a-stick and I'm pretty sure I've seen almost every surface inside my engine and there's no piston ring to be found. If it did fall off, it was entirely HALF of a ring, and it's hard to believe it would just disappear in there.

now thats gona be hard to fix.lol.


it was ment to be an image ofmyne but i cant upload it

I got everything back yesterday. The mechanic suggested I test the valve clearances before putting it back together. That leaves these tasks:

Rock the bike back and forth with a magnet probe in the crank case and hope 1/3 of a piston ring shows up. (I have no idea where it could have gone at this point.)

Locate new piston wrist pin circlips (these are rare, for some reason).

Use a razor and gasket remover and patience to clean surfaces for generator gasket, oil pan gasket, base gasket.

Sandpaper oil pan smooth, seal it up with Permatex Ultra Black and an oil pan gasket and hope for the best.

Learn about valve clearances, then test them. Cry if they're no good.

Reassemble and hope I've cleaned off the gasket surfaces well enough.

well i need new gummed piston rings. on all 4. lol. and new gudgeonnpin circlips x8. lol. where the hell do i get these from and another thing... how do i get the two lower pistons to move up so i can get them off. lol.
oh and it needs to be honed...


??????

Ouch.

staniel wrote:

GLORY day!

I got a call from the shop today. The bump honed out. I need a new set of piston rings (original size), but that's pretty much it from here.

So, why do you need the cylinders honed if they have already honed them? Surely they didn't hone just one cylinder?

I'm pretty sure I have 4 sets of new standard 750 rings around here somewhere.

If you can't rotate the crank to move the pistons up then the cam chain is probably wedging the crank at the bottom. Pull the cam chain up.