Question on KZ650 Cyclinders

wrote:

wrote:

The 550's have a history of wiping out crank/rod bearings.


 

Really, never heard about that before.  I have heard that when raced the 750’s would spin the mains under hard braking due to the oil pickup un-porting.  How do they fail?


Thanks
577nitro

Back in the day, when I was doing a fair share of buy-fix-flip'ing, I came across a couple Gpz550's with noisy cranks/rods, which research led me to believe, weren't super rare.  A quick archive search here turned up this thread.  

www.kzrider.com/forum/2-engine/238666-gp...obable-cause?start=0

wrote:

wrote:

The 550's have a history of wiping out crank/rod bearings.




 

Really, never heard about that before.  I have heard that when raced the 750’s would spin the mains under hard braking due to the oil pickup un-porting.  How do they fail?


Thanks
577nitro


 

Where did you get that info?

Have you ever looked at a 650/750 oil pan?? It has a cast in "wall" that is similar to the 900/1000 but a bit tighter to keep oil on the crank plus the 750 oiling system was improved over the 650 which is a high pressure system to start with.*****************************************************************************

1.  The info was from a guy who raced them back in the day and worked at a large Kawasaki dealer in CO.

2.  No I have not looked at one...but from your description it seems this dude didn't know shit from shineola.  Good thing he was a Kawasaki dealer employee.

Thanks for the information.

577nitro

wrote:

wrote:

I know the answer but I want to hear the why first.







 

And....????????






 

I don't know where your getting your information from but its incorrect.

The max a 650 liner can go too is 65mm (720cc) and then it is very thin as in "race" (.070" per side) The 750 (738cc) piston is 66mm stock.

The 650 liner is 68.5mm OD!!!!!!!!!!!!!

Your idea of increasing the wrist pin diameter is very dangerous to your project. Those type of modifications are generally used on race engines that don't see any miles, but feel free to modify away.

If you did the math you would find out the piston speed for that bore/stoke combination, along with that dodgy con rod mod is bound to have a catastrophic failure. That is why it is best to stick with proven overbore combinations that are sitting on the shelf.

There are many GPZ550 guys on here, been on here for donkeys ages. If it would be possible to go bigger it would have been accomplished already.... maybe 15 years ago.**************************************************************************************


Hey I was just asking questions here I'm the first to admit I know dick about the 650 cylinder sizes everything is a best guess based on what little info I had on hand.  

Didn't mean to offend anybody..just asking questions that's all. 

Thanks for the information, its all good stuff.  Sounds like the #3 bearing on the 550 has issues from the post I read from Corey.   

Thanks
577Nitro 

A Wiseco big bore kit would be COOL!  There is more than a few of those running around, so that's a good sign.  

wrote:

wrote:

wrote:

I know the answer but I want to hear the why first.









 

And....????????








 

I don't know where your getting your information from but its incorrect.

The max a 650 liner can go too is 65mm (720cc) and then it is very thin as in "race" (.070" per side) The 750 (738cc) piston is 66mm stock.

The 650 liner is 68.5mm OD!!!!!!!!!!!!!

Your idea of increasing the wrist pin diameter is very dangerous to your project. Those type of modifications are generally used on race engines that don't see any miles, but feel free to modify away.

If you did the math you would find out the piston speed for that bore/stoke combination, along with that dodgy con rod mod is bound to have a catastrophic failure. That is why it is best to stick with proven overbore combinations that are sitting on the shelf.

There are many GPZ550 guys on here, been on here for donkeys ages. If it would be possible to go bigger it would have been accomplished already.... maybe 15 years ago.**************************************************************************************


Hey I was just asking questions here I'm the first to admit I know dick about the 650 cylinder sizes everything is a best guess based on what little info I had on hand.  

Didn't mean to offend anybody..just asking questions that's all. 

Thanks for the information, its all good stuff.  Sounds like the #3 bearing on the 550 has issues from the post I read from Corey.   

Thanks
577Nitro 

 

I don't know how you took the !!!!!!   I only put it in there to match your ??????
Sorry if that came off as anything else other than playful and for sure no offense was intended or taken.

The OD I gave you is accurate, I have a liner sitting on my office desk.

With these KZ/GPZ bikes you can do almost anything, but there is a limit. With the 550 I know ZERO, but with the 650 its a different matter.

I think I have a picture of a 650 motor in a GPZ550 but admit I can't find it in my folders (probably mislabeled)

As far as the enlarging of the con rod small end, Kawasaki did not leave a lot of meat on those on the smaller engines, the exception being the 900/1000/1100 motors.

Is this project a whole bike or just a barrel? I see in the "projects" section you have a KZ650.

 

wrote:

A Wiseco big bore kit would be COOL!  There is more than a few of those running around, so that's a good sign.  

 

I agree,  I think this is the route I'm going to go for sure.   This is all going on a frame off 81 gpz550 restoration that's been in the works for years.   

I finally got all of pieces and time to assemble it.   I even found brand new oem nos coils...left and right from Thailand!  And it only took two weeks to get!   

 

The 650 is a new purchase, and I haven't really started anything on it yet, but I think it will eventually become a frame off.   I really think it's a cool bike, first 650 I've owed and just love the way it looks, the stance, eveything.   I've been looking for one for years but it seems all KZ's have dried up including the 650's.   My theory, which maybe full of beans, is that foreign buyers are buying up all the old classic aircooled bikes and shipping them overseas to collectors and custom bike builders.  First went the big bore and two strokes...now even the small and medium bore bikes.   Look on Craig's list and all you see are "Want to buy your old Kaw, Honda etc.." ads.

Right now I'm assembling my frame off 81 gpz550.  

577nitro 

 

wrote:

The 650 is a new purchase, and I haven't really started anything on it yet, but I think it will eventually become a frame off.   I really think it's a cool bike, first 650 I've owed and just love the way it looks, the stance, eveything.   I've been looking for one for years but it seems all KZ's have dried up including the 650's.   My theory, which maybe full of beans, is that foreign buyers are buying up all the old classic aircooled bikes and shipping them overseas to collectors and custom bike builders.  First went the big bore and two strokes...now even the small and medium bore bikes.   Look on Craig's list and all you see are "Want to buy your old Kaw, Honda etc.." ads.

Right now I'm assembling my frame off 81 gpz550.  

577nitro 


 

Your theory is correct but its been happening for over 10 years now.
We have a local summer swap meet here and I met one of those "buyers".
June of 2010 I had a conversation with a middle aged Japanese gentleman that was at the meet looking to buy in order : 73-75 Z1, early CB 750 Honda, and any Kawasaki 2 Stroke.
He said he had a container full of bikes at the Port in Montreal. He whipped out a 2 inch wad of hundreds, cash money on hand and more if required.
He specifically came to Canada to buy 2 strokes.
When I mentioned I was into KZ650 he was not interested, he kind of poo pooed them.
They are a very nice machine but they never had a cult following like some others.
They never really reached the cult status of bikes like the Z1 or CBX.
 

wrote:

wrote:

The 650 is a new purchase, and I haven't really started anything on it yet, but I think it will eventually become a frame off.   I really think it's a cool bike, first 650 I've owed and just love the way it looks, the stance, eveything.   I've been looking for one for years but it seems all KZ's have dried up including the 650's.   My theory, which maybe full of beans, is that foreign buyers are buying up all the old classic aircooled bikes and shipping them overseas to collectors and custom bike builders.  First went the big bore and two strokes...now even the small and medium bore bikes.   Look on Craig's list and all you see are "Want to buy your old Kaw, Honda etc.." ads.

Right now I'm assembling my frame off 81 gpz550.  

577nitro 



 

Your theory is correct but its been happening for over 10 years now.
We have a local summer swap meet here and I met one of those "buyers".
June of 2010 I had a conversation with a middle aged Japanese gentleman that was at the meet looking to buy in order : 73-75 Z1, early CB 750 Honda, and any Kawasaki 2 Stroke.
He said he had a container full of bikes at the Port in Montreal. He whipped out a 2 inch wad of hundreds, cash money on hand and more if required.
He specifically came to Canada to buy 2 strokes.
When I mentioned I was into KZ650 he was not interested, he kind of poo pooed them.
They are a very nice machine but they never had a cult following like some others.
They never really reached the cult status of bikes like the Z1 or CBX.

 

Back in the '90's we used to have two gentlemen from Germany that came over every fall to all the dealerships around the Chicagoland area. We used to call them Hans and Hans. They came with a briefcase full of cash. They were after new and used parts for Kawasaki triples, Z1's to Kz1000's, and CB750's.  Not some much for whole bikes unless they were a steal!!!! They knew their Kawasaki parts and their prices. Stock exhausts, and air boxes they would pay big bucks for!!! Every take off exhausts we had hanging in the service department they wanted. They always wanted a package deal for them. Our dealership in the wintertime always had a cash flow problem. So we loved to see Hans and Hans with their briefcase of ca$h!!!! 

wrote:

The 650 is a new purchase, and I haven't really started anything on it yet, but I think it will eventually become a frame off.   I really think it's a cool bike, first 650 I've owed and just love the way it looks, the stance, eveything.   I've been looking for one for years but it seems all KZ's have dried up including the 650's.   My theory, which maybe full of beans, is that foreign buyers are buying up all the old classic aircooled bikes and shipping them overseas to collectors and custom bike builders.  First went the big bore and two strokes...now even the small and medium bore bikes.   Look on Craig's list and all you see are "Want to buy your old Kaw, Honda etc.." ads.

Right now I'm assembling my frame off 81 gpz550.  

577nitro 





 

Your theory is correct but its been happening for over 10 years now.
We have a local summer swap meet here and I met one of those "buyers".
June of 2010 I had a conversation with a middle aged Japanese gentleman that was at the meet looking to buy in order : 73-75 Z1, early CB 750 Honda, and any Kawasaki 2 Stroke.
He said he had a container full of bikes at the Port in Montreal. He whipped out a 2 inch wad of hundreds, cash money on hand and more if required.
He specifically came to Canada to buy 2 strokes.
When I mentioned I was into KZ650 he was not interested, he kind of poo pooed them.
They are a very nice machine but they never had a cult following like some others.
They never really reached the cult status of bikes like the Z1 or CBX.
****************************************************************************

Well that explains the shortage of used bikes.   I haven't seen a two-stroke of any kind for sale in a long time.    I just picked up a 72 H2 barn find from a friend two months ago...took two years to finally get him to sell it to me.  It's really rough but eveything is there and you can get any part for it...which I guess is a testament to the collector craze for them.   I got two spare engines with it as well.   The H2 is novel but not a rider as its just too damn valueable as a collector bike, same with my old RZ race bike.  However, my 650 is going to be riden a bunch...its a mini Z1!     I say we don't tell anybody how great they are and maybe they will remain available and affordable!   I did see that Kawasaki has introduced a kz650 retro now, which I think looks awesome!   I love the green paint on it.

Keep them a secret!  



 

I might have to elaborate on my story about the "disappearing" bikes.
Its been way more than 12 years as I confirmed with a friend of mine and he mentioned that same Japanese guy had been showing up at the swap meet for 6 years prior to that conversation.

In Japan they were mandated to only have up to 750cc bikes even though they were exporting the Z1.

I know I am also a culprit in my locality. After that conversation I bought up every used/basket case KZ650 within a 2 hours drive that was less than $250 (now own 7 of them)
Now you can't find a runner for less than $2K

The great American Z drain has been going on since the early 90's at least. UK & Europe have been importing, especially early Z's and triples, by the container load. There are several companies doing this in the UK that have been around for 20+ years.
They have been a source for parts/spares well known to the clubs. There are probably more US import 900's on UK roads than UK bikes.