bottom end

so I've got the top end of this thing off, (78 KZ650B ) the cams dont look like they have much wear at all. Valves are .003 - .004. So now I am going to pull the bottom end to look at it. (why, cuz I just bought this and want to see exactly what I have, and it needs a starter clutch anyway)

So once I pull the crank, even if the bearings look good should I plastigauge them and see how much clearance there is?? Rods get plasti too right??

all my 2 strokers have the segmented crank with ball bearings. To me plain bearings seem to be a step backwards. I know it eliminates having special crank tooling and a special service manual just for the freekin crank, but anyone care to make some intelligent comments here about why plain bearings?

they are better above 10,000 or so rpms when roller bearings become sliders,but i dont spend much time above 10,000 rpms anyway!:laugh:

i guess the fact this web site stays getting new old kawi riders 36 yrs after selling the first z-1 and some are still riding around on the 36 year old crank bearings(i am) with no problems is reason..jzanutto wrote:

so I've got the top end of this thing off, (78 KZ650B) the cams dont look like they have much wear at all. Valves are .003 - .004. So now I am going to pull the bottom end to look at it. (why, cuz I just bought this and want to see exactly what I have, and it needs a starter clutch anyway)

So once I pull the crank, even if the bearings look good should I plastigauge them and see how much clearance there is?? Rods get plasti too right??

all my 2 strokers have the segmented crank with ball bearings. To me plain bearings seem to be a step backwards. I know it eliminates having special crank tooling and a special service manual just for the freekin crank, but anyone care to make some intelligent comments here about why plain bearings?

I don't know how many miles you have on the engine, but hey as long as you have it apart go for it. As far as why they use standard bearings instead of rollers, I don't really know for sure but I'd have to say its got something to do with the fact that they have oil injected into them through the crankshaft unlike 2-strokes. This allows them to uses standard bearings which are light, have tighter clearances with less maintenance, and are alot easier to replace. Thats just my opinion though.

well should I plastigauge while its apart?? I have to lift the crank out to get the new timing chain in anyway.

also, does that big mesh drive chain wear at all?

yeah check em as long as youve got the caps out,you can measure the primary chain for stretch also.

that primary chain looks expensive

expensive ? bwahahahaha ! welcome to the world of motorcycling.

According to the book, you measure the slack in the primary chain while it is mounted in much the same way you check the drive chain slack. The FSM gives 27mm as the service limit. These chains are pretty tough, they were used on numerous 650 and 750 models, so unless yours has very high milage or was run with dirty oil it is probably ok. The good news is if you do need one they are still listed as "Active" on the Kawasaki site (probably because they were still in use as late as 2005 on the ZR750H5). Ron Ayers lists the price as $186.58 but Z1 may be able to beat that. Ed

jzanutto wrote:

well should I plastigauge while its apart?? I have to lift the crank out to get the new timing chain in anyway.

I would. New bearings would be really easy to install while it's open.

jzanutto wrote:

also, does that big mesh drive chain wear at all?

It shouldn't wear much. I think it's swimming in oil when it runs.

ok its out and half apart. this thing looks pretty clean inside so far. I was able to stick my finger down and feel some play in that primary chain, but I will officially measure it when I get it split apart.

I just pulled the oil pan and measured the play in the primary drive mesh chain. It's still well within limits