kz650 1978 Q/A

In process of rebuilding engine. Cases split and I have bunch of questions

1. What is this white stuff on bolts? Is that a factory thread locker? I don't see any indication of someone being in engine yet but I do see engine assembled with white paint-like sealant. there is even runs. See on picture, some of it is next to crank on areas not even needed. What's interesting - left side bolts have a lot of it on threads and right side bolts - none. So, what should I use for reassembly and do I need any thread locker on bolts?

2. Any suggestion on gasket /seal/oring kits to take care of everything?

3. I am going to go through all the checks listed in factory manual (gaps, sizes, etc). However, any specific places to look at while in there?

4. Clutch basket/gear has some play. Is that by design or need to do something about it?

5. What is the typical crank life? From my "ballpark" checking - it looks very good for 26k miles. Will measure but no difference between individual rods or.. Should I even think about rod bearings and main bearings on crank?

6. Should I think about bearings in secondary/other shafts? Or those last long time? What about main chain?

7. I did screw up removing flywheel. I did remove bolt. I did try screwing rod (part of ball joint splitter tool) to push on crank - no way. Then I used 2 jaw puller. And still don't work. But I did crack magnets because puller pushed on sides. Special tool on order. Just not sure how this going to work because it's there tight..

On topic #4 - the clutch basket has six rubber dampers between the gear and the basket itself. You can drill out the factory rivets to disassemble it and replace the bushings (there’s a guy that makes them for about $50 for 6), but it won’t take up 100% of the free play (in my experience).

#1 The white residue looks like the remnants of 40+ year old ThreeBond case sealer to me. It was very thin, and at the time probably still applied with a brush, I usually used my trigger finger. No factory thread locker on bolts.
#2 The concensus on the Forum seems to be use Genuine Kawasaki gaskets when possible, they do not come as a kit, but need to be ordered individually
#5 IMO at 26K miles you should have insignificant wear on main and rod bearings if the bike was properly maintained. You can do a quick check of clearances with Plastigauge.

#7 hopefully the special tool for rotor removal will work for you, it is designed to thread into the rotor and push on the end of the crankshaft without damaging it.

Mike

I have an engine completely disassembled right now.

1 - Probably engine case sealer.

2 - For base and head gaskets, use OEM. For the rest it doesn't matter much. Use 3 bond to seal your cases. Spread thinly.

3 - Check everything mentioned in the manual. Consider replacing your timing chain if you plan to put a lot of miles on the bike.

4 - Check your gear backlash. I think the book has a spec.

5 - Check the journal bearings.

6 - For roller bearings...any play or noise means replace.

7 - Do what the manual recommends. Use the special tool, when it is screwed in far enough to contact the end of your crankshaft you need to tap on the end with a hammer while continuing to tighten the special tool. It worked for me.

On the larger bikes, you can use the rear axle instead of the special tool to remove the flywheel.

Replacing the clutch hub dampers and those in the secondary shaft sprocket is recommended. You may want to look through the build thread linked in my signature for more details.

Nessism wrote: Replacing the clutch hub dampers and those in the secondary shaft sprocket is recommended. You may want to look through the build thread linked in my signature for more details.

Getting those from turbosteve. Do you know if secondary shaft ones available from someone?

I noticed you welded clutch back. I’d rather go this way vs tapping etc. any concern with heat damage during weld? Or you cooled after each bolt?

No eBay APP ID and/or Cert ID defined in Kunena configurationDoth this kit look legit? Cheap than aftermarket kits

Welding was done part way around each rivet and then moving to the next. I'm not sure how many steps the welder used but at least two, but maybe more. He used silicon bronze filler which melts at low temp too.

Regarding that gasket kit, stay clear. They were a Kawasaki aftermarket kit so in theory they should be decent, but they haven't been made for 35 years and the gaskets are sure to be hard and crumbly. I know this because I bought one and it was completely degraded. Had to return it for a refund.

Nessism wrote: Welding was done part way around each rivet and then moving to the next. I'm not sure how many steps the welder used but at least two, but maybe more. He used silicon bronze filler which melts at low temp too.

Regarding that gasket kit, stay clear. They were a Kawasaki aftermarket kit so in theory they should be decent, but they haven't been made for 35 years and the gaskets are sure to be hard and crumbly. I know this because I bought one and it was completely degraded. Had to return it for a refund.

Will try to weld fast and cool each one

For gaskets, this kit is not Kawasaki then? Or some kind of 2nd grade kit? If it is Kawasaki then any individual gaskets will be just as bad, no?

Interesting gasket kit. Kawasaki must have made and sold kits at some point. If you look on the bottom left corner....the yellow sticker...there is no computer code on it, which means it is pre-1990's or thereabouts. I haven't ordered any gaskets for my engine rebuild yet, but when I do I'll order via Partzilla or go directly to a Kawasaki dealer. Again...I will only order the head gasket and the base gasket OEM. I'm fine with jobber gaskets for the rest of the build.

Hi

The only good after market gasket kits I'm aware of are by Vesrah from Japan. They've been around for donkeys years and I've used them a number of times. I also know a couple of bike mechanics and parts suppliers localy who recommend them. You could still use a genuine head gasket, but to be honest, I can't fault the Vesrah ones.

When rebuilding it I would have a close look at the starter clutch. From personal experience it seems to be a weak spot and often wears out. Not a problem if you've got a kick start! Thats part the reason I fitted a 650 kick start to my 750 when I rebuilt it, although the main reason is I just like kicking an engine into life!