KZ650 cafe-racer

With all components in place I just checked gearbox fitment:

 

 

 

And then installed the transmission in the upper half of the crankcase. Both halves of the engine case were ready to be joined…

 

 

 

Did you replace the primary Chain Gazzz ?   If so, where did you get it ?
Engine looks great, clean enough to serve dinner on...!

Thank you!

I considered all possible sources of primary chain and it turned out that the best option is Japan Webike.

I think many KZ650, KZ750, GPZ750 and Zephyr 750 owners, who overhaul engines of their bikes have questions if the primary chain needs to be replaced. This part is expensive, so no wonder that thinking about this issue may not be easy. Kawasaki KZ650,KZ750 and GPZ750 books say that the service limit for chain slack is 27mm.

It seems to be clear: if the service limit is achieved or exceeded, the chain has to be replaced.  However, the chain itself looks to be tough and “lifetime” lasting. With high mileage it may become noisy, however, I’ve never heard about cases of broken primary chain.  For example, my own Zephyr 750 has mileage close to 100K kilometers and it still runs the original primary chain. In fact there is information available about motorcycles with 160K  and more kilometers that still have no trouble with the primary chain. Well, I decided to dig deeper into this matter.

Kawasaki Zephyr 750 and ZR7  engines share part number of primary chain with KZ650-750 as both are their direct descendants.

First thing, I took a look into ZR7 factory service manuals. I wasn’t surprised not finding any information on primary chains there, because the Kawasaki ZR7 engine is equipped with the tensioner.

Some time ago I received the newest of available editions of the Factory Service manual for Zephyr 750 (part number 99924-1138-03, printed in 1997). As I already mentioned, Zephyr 750 has the same part number for the primary chain as its predecessor: KZ650 and KZ750. And similarly to them Zephyr has no primary chain tensioner. So, information provided by the aforementioned factory service manual may be considered as the final word of mother Kawasaki about primary chains of 650-750 KZ-s, GPZs and Zephyrs.

Now guess what service limit Zephyr 750 newest factory manual states for primary chain?

Drum roll….

Answer: none. There is no service limit for primary chain slack and the procedure of its measuring is completely and totally absent. The only indication of issues with the primary chain I found was in troubleshooting where it was said that if there is extensive noise, the primary chain has to be replaced.

So it looks like Kawasaki decided that the primary chain for our engines lasts as long as it isn’t too noisy for the ears of motorcycle owner. But sure, it’s up to you to make the final decision. If you are building a fancy and looking-like-new engine I’d rather recommend replacing the primary chain while you are still sorting out the engine. Doing it later may end up in additional expenses like gaskets, O-rings and so on.

Hi Gazz, thanks for that, I'd found webike was about the most reasonable priced around too. My bike has over 100'000 on the engine and it doesn't look like it was "user friendly" miles, the engine has been rebuilt at some stage but it wasn't done very well. Did you know that the CB900f Boldors use the same primary chain ? I expect that with the smaller power out put of the 750 that they would be plenty tough. I've also looked at a few low mile primary chains for sale and that seems to be a cheaper way to get a "better" chain, one member here did exactly that. I've been looking for a new cam chain as well, i recently found out that DID still make chains for our bikes, they have an SCA-0412-SV150, and also a slightly stronger SCR-0412-SV150, they both claim to last up to 3 times longer with proper maintenance . The 750 cam chain is the same as the 1996 to 2006 Suzuki bandit, the 1988 to 1992 CBR1000F and the XJ900s diversion from 1995 -2003.....

Yea, I know about the Honda CB900 primary chain (13610-438-004).  Personally I have doubts about if it’s stronger than the KZ chain. I think it’s more likely Honda decided that such a chain (equipped with a tensioner, by the way) is enough for 900ccm engine. But it’s only my guess. As for the facts: the number of plates in every column of the CB chain is identical to those of KZ: 9-8. Thickness of the plates seems to be identical too. Therefore, the only way to get the answer for the question about these chains' strength is to lay both of them side to side and make measurements.

  The Honda primary chain used to be cheaper than Kawasaki chain, so no wonder it was in demand among Kawasaki owners. However, nowadays there is a clear issue with the Honda CB900 Bol D’or primary chain which makes it less desirable.  These days Honda genuine chain is “is no longer available” from most of the suppliers and there are too many not only non OEM but completely “noname” products on market. Some sellers state that “product is as good as OEM” or “Made in Japan”. And the fact is: a lot of low quality products were sold and still are on sale under those mottos…

  The prices of CB900 primary chains that still have OEM packaging to prove their origin are mostly equal or higher than that of KZ from Webike. Therefore, personally I voted for the OEM Kawasaki primary chain. It lasts long enough to be worth every dollar thrown in it.

  As for the D.I.D timing chains. I like them, however they are more expensive than OEM chains.  I used a DID 05T-118lE roller timing chain for KZ650 and DID  SCA-0412-SV146LE chain in my Honda CB750 project. I also have a Hiwo DID SCA-0412-SV150LE timing chain for Kawasaki Zephyr 750 in my stash of parts.

Any way to add the ZR7 tensioner to a 650/750?

The tensioner is built-in the ZR-7 lower engine case.  It is part of it.                  ...and Kawi added it  to 'civilize' the air cooled engine noise against the liquid cooled Suzzi SV650, the reason for the ZR-7 existence,  until the Versys 650 was developed. 

Any way to add the ZR7 tensioner to a 650/750?

I have never dismantled a ZR7 engine, but as I was interested in the question of the tensioner I dug up as much information as was available. And it turned out that the only way to get tensioner is to use the complete ZR7 bottom.

Upper half of the ZR7 engine case has two additional mount points for the upper primary chain guide. Lower half is even more heavily modified: not only mount points were added but a whole new protrusion in front of the lower case (where Zephyr and KZ have none).  It is also not uncommon for primary chain tensioners to be not only spring operated but also have oil feed. However, in the case of ZR7 I couldn't say for sure if it has oil feed or not.

I had no time for photo shooting  when I was applying sealant on crankcase contact surfaces. So next photos I took were those of the engine case already assembled, with all bolts torqued to specs.


 

 

 

My next task was pistons and cylinders. First thing I installed new original plugs into the bottom of the cylinder block.

 

 

 

Wiseco forged pistons look as always fancy.