1982 KZ550 C3 Engine Rebuild

I am currently in the process of doing a top end rebuild on a 1982 KZ550 C3 LTD and I would like to make a general progress / questions thread about it. I am the third owner after having purchased it for 800 from a family member. The bike itself has anywhere from 30k to 45k miles as it is currently on its 4th tachometer. It has been laid over / wrecked 3 times by the previous owner, who fixed it just enough to be rideable. I am not looking to fully restore it, just to make it reliable again and get it back as close to factory as possible. I would also like to say from the outset that am not looking to ever get my money out of this. I know anything I spend on it will be gone forever.

I have a factory service manual for the bike, it is a reprinted and bound version from RepairManual.com (pics below) as I was having a difficult time finding an original. This one seems to be just as good as what it was copied from so it works for me.

I also have a second 1982 kz550 c3 that is still mostly intact to pull parts from. I found this one listed on craigslist for $150, with the caveat that there is no title, and someone has pulled the ignition and seat lock. The guy selling it said he went to buy a scooter from someone and they had the KZ sitting in a corner of their barn so he picked it up to sell it on craigslist. It has license plates on it and was last registered 20 years ago so it was a perfect parts bike.

Here is where I am at now:
Last rode it in May 2015 to move it to a new house I am renting. It was running rough and had been for a while before that.

The carbs have been rebuilt with new gaskets, o-rings, and screws. Upon pulling the carbs I discover that 2 out of 4 choke flaps were gone so I replaced all of the choke slides with the set from the second bike as the hinges on the remaining two look like they were ready to break. I need to double check the float level on #2 but other than that they are ready to go back on. I have a carb sync kit and will do that once they are back on. I have brand new carb holders and carb intake boots ready to go on as well.

I have replaced all of the gaskets on the transmission cover so it no longer leaks around the shifter and secondary shaft.

I did a compression test on each cylinder and was unable to get a reading over 80 psi on any of them, this is hot reading with oil added to the cylinders.

I have also checked the valve clearances, the exhaust valve range from .10 to .13 mm, the intakes however are .06 and under .04 for the other three valves so they will need to be redone when possible.

I have pulled the cylinder head and cylinder assembly, and that is where I am at now. I have discovered that one piston ring is missing a large section. Other than that I need to get a plan together to measure clearances, clean parts, and get replacement gaskets, o-rings, and hard parts as necessary.

Factory Service Manual


Before the seat cover replacement (It got a lot worse shortly after this was taken):


New seat cover:


Before transmission cover gaskets / o-rings:


After:


Current Conditions:



TODO:

• Remove valves, replace and lap as necessary
• Clean cylinder head
• Clean cylinder assembly
• Clean engine block
• Clean pistons
• Check clearances on pistons / cylinders and figure it out from there
• Replace triple tree / forks using set from other bike, as one fork has a rusty spot and stripped bolt
• Fork seals on replacement set
• Install LED flasher module, all bulbs have been replaced, just need the module now.
• Use exhaust from other bike as it isn't as rusty / damaged by previous owner
• Replace air box as previous owner drilled holes in it (for performance reasons :S)
• Replace front sprocket and chain

My shopping list

This is what I have come up with so far, I will add and remove as necessary.

Well with a broken ring and that poor of compression you may want to plasti gauge and check bearings while its open. That's pretty poor compression, I believe the service limit is 150psi. There are online versions of the 550 Kaw FSM and see Loudvx 's profile or post signature for links to all things 550 and a FSM. The choke flaps got eaten in the motor and may be causing some of you problems. They are pretty soft and from what I have read usually do not cause a catastrophic problem, but they could. Where's the oil leak? While your at it check out my 81 550 Update thread. I have been bringing a low mileage one back from the dead after it had been sitting outside for 10 years+. Welcome R

online versions of the 550 Kaw FSM and see Loudvx 's profile

I purchased the FSM when loadvx's hosting disappeared, but I decided I would rather get a physical copy as my laptop doesn't take kindly to dirt and oil.

Where's the oil leak

The oil leak was from around the shifter as seen in the photo above, it wasn't readily apparent at first due to the build up of chain lube and dirt.

plasti gauge and check bearings

I have now watched this platiguage video on Youtube and will look into it. One question I have is to remove the connecting rods / bearings, do I need to pull the engine or do I have access from the bottom? My FSM doesn't go further than piston heads with the engine installed.

I was thinking cam bearings as the pistons and valves are where the compression is at. If your cams bearings are worn and out of spec no valve adjustment will compensate for the worn bearings and compression will be lost because the cams won't actuate valves correctly. The bottom end is not under compression and is vented to the atmosphere via the breather to prevent pressurization and gasket failure. I think you could get the rods out but IMO to do proper crank bearing inspection and measurement and rod installation the engine should come out to fully remove the oil pan. Smarter folks than me on here though Do pics, I'll be watching. R

The 550 runs the cams on the head. No bearing inserts.

Assuming you don't have any knocking noises from the bottom end, a top end refresh should fix you up. Good plan on getting the cylinder and pistons measured up. If you have more than .001" out of round or taper in the bores the cylinder is done. Also, no more than .004" piston to cylinder clearance. If it all checks out then run a 240 grit flex hone down the cylinders to break the glaze and install new OEM rings.

For the head, pull the valves and inspect everything there too. A light seat cutting and valve faceing will go a long way. And be sure to tell your builder to kiss the valve stems too, just a few thousands should do.

Cleaning the cylinder head with a Harbor Freight soda blaster:

Check the valves for possible nicks on the seats. Sometimes a choke flap will get caught in a valve. I don't know how, but they usually make it through without the owner even knowing. Still seems impossible.

The site is back up for now. But I'm not sure how permanent it will be. I'm testing the Amazon server, which is free for awhile. We'll see how much they actually charge after the free trial. I urge everyone to download and save on their computer. It's the only way to know the info will be available.

Here is the current shopping list as I can't seem to edit the other one. I have picked up the Z1 full kit, which somehow ended up costing $1 less than just the top end kit. I have decided that I am going to pull the head on the other bike and use it instead, as there is a lot of pitting on one cylinder die to ingesting a choke flap. There is also some damage around the top of the piston on the same cylinder.

I have one of these: K&L Supply MC25 Metric Engine Stand arriving today for the rebuild.

Progress

Now the fun begins. I have some vids of the same processes in my thread 1981 KZ550 Update.

While it's open, definitely replace the main crank seals, that's the only reason I cracked mine. The seal had rust damage on the ignition side. And all seals too for that matte. Those man seals are likely compressed and will not seal up if used again. Flywheel has to come to replace the other seal. I don't know what ya have a for a flywheel holder, but my valve spring compressor worked perfectly. Good job and continued good luck!.

R