Z1 head camshaft tunnel line boring specs

Hi new to the group and getting used to navigation. I am after anyone who has the specs to have the camshaft tunnel line bored or previous post from Larry C on how to get over the dilemma of swapped lost original mating caps and now  with some spare caps , the cam locks solid so this is where I am. Thanks in advance 

Only my opinion but I'm not sure what you are suggesting is possible for the following reasons

• To the best of my knowledge nobody produces oversize/undersize bearing shells for these motors 
• it is not uncommon for these heads to twist slightly when removed (which rights itself when torqued down on the motor) so clamping it to a boring table may not truly replicate it's rest position on the motor

Have you installed the cams with the head torqued down in situ and do they still lock up ?

When rebuilding an engine, like an old american V8, the main bearings can be "Line Bored" to resize the block/main bearing caps.  This involves first skimming a few thousands of material off the caps, then reboring the bearing saddles with a special, and expensive machine.  No doubt, Kawasaki has a special machine they developed for boring those cam bores, but trying to replicate that would be challenging for sure.  

I remember some old posts by Jay from APE, where he warned against big decking cuts off a cylinder head in an attempt to straighten a warped head.  While you can remove material and true up the deck surface and make it flat again, he said on heads like this, the cam bores will be off as well, and there is no reasonable way to fix those.  For that reason, he said that badly warped heads should be first straightened in a press, and only after it's returned to reasonable straightness, should it be decked.

Bottom line, if the cam binds due to having the wrong caps, you got a problem on your hands.  Steve posted many long videos on how he went about trying to save a head that were missing caps (or something to this effect.)  The simplest path would be to buy a new head.

Too bad you see all those head on ebay without caps. Sellers think they can sell the head and caps separately 

Nessism wrote:

When rebuilding an engine, like an old american V8, the main bearings can be "Line Bored" to resize the block/main bearing caps.  This involves first skimming a few thousands of material off the caps, then reboring the bearing saddles with a special, and expensive machine.  No doubt, Kawasaki has a special machine they developed for boring those cam bores, but trying to replicate that would be challenging for sure.  

I remember some old posts by Jay from APE, where he warned against big decking cuts off a cylinder head in an attempt to straighten a warped head.  While you can remove material and true up the deck surface and make it flat again, he said on heads like this, the cam bores will be off as well, and there is no reasonable way to fix those.  For that reason, he said that badly warped heads should be first straightened in a press, and only after it's returned to reasonable straightness, should it be decked.

Bottom line, if the cam binds due to having the wrong caps, you got a problem on your hands.  Steve posted many long videos on how he went about trying to save a head that were missing caps (or something to this effect.)  The simplest path would be to buy a new head.

Absolutely agree, line boring in the car world is quite common as manufacturers produce a range of under/over sized bearings. This allows the removal of material to rectify "ovality" etc and then the fitting of a thicker bearing to compensate for the removed material - in this case I am not aware of any options for cam bearing dimensions

Cra-z1 wrote:

Too bad you see all those head on ebay without caps. Sellers think they can sell the head and caps separately 

Same as crankcase half's for motors with "shell bearing" cranks - same scenario

Odd caps can be used but you need the head bolted down on the block or surface plate, a bucket full of spare caps , a bore gauge and know what you are doing.
Any numbered cap can be used in positions 2 and 4 but 1 and 3 must use a either a 1 or 3 cap as these control cam end float.
Any adjustments must be confined to the caps only and not the head.


 

zed1015 wrote:

Odd caps can be used but you need the head bolted down on the block or surface plate, a bucket full of spare caps , a bore gauge and know what you are doing.
Any numbered cap can be used in positions 2 and 4 but 1 and 3 must use a either a 1 or 3 cap as these control cam end float.
Any adjustments must be confined to the caps only and not the head.



 

Knew you would have the definitive answer 

I'm still using the "Junk Head" I bought for $20. I got it for the valves, lifter cups and other things. It came without caps. I went back and found some but they wouldn't work as they were. A friend told me of a R22 head he had where he had the same problem. He honed them to make them fit. With that in mind I set out to do the same thing. One was too far out so I couldn't use it. Clay said he had a J head that was too far gone so he offered to send me one to see if it would fit. It did and I asked him if he had another so he sent me another one. As it turned out 1 and 4 were close enough to hone to size but 2 and 3 would only work if fitted backwards. The specs. are .001-.006 so with a Plasti gauge I honed them to fit. While I was at it I ported the head to clean out the casting marks and slag plus the shelves around the inside of the valve seats. Just a clean up and matched the ID's of the intake manifolds. I worked on here and there over a few months until it was done. Being the head I had on the bike needed a complete overhaul I switched them and what a difference. The bike came ALIVE.   I had a problem with the spark plug threads but that's another story. It ran so well the clutch started slipping in 2nd gear on hard takeoff. Just a little cleanup porting was a good move. 
So it can be done and I figured all I had to lose was time and a $20 junk head. 
I'm still using it today with my new 1075 kit installed and I'm RIDING THE PISS OUT OF IT.
Steve
. 

www.kzrider.com/forum/2-engine/619036-an...tion?start=12#885778

SWest wrote:

So it can be done and I figured all I had to lose was time and a $20 junk head. 
I'm still using it today with my new 1075 kit installed and I'm RIDING THE PISS OUT OF IT.

Steve
. 
 

Steve I've gotta say it sounds like you got lucky with that one but it's not a solution I would advise anyone else to follow (what you do with your own is your business) We have all stripped motors and found things that make us wonder how they were still running !!!
Unless you honed it on a milling table I'm not sure how you maintained the hone at 90 degree's on 2 axis ?? So although the cam to bearing clearance may be in spec I don't see how there can be even clamping force on the back of the bearing shells so it's a bit of a lottery !!!
In answer to your retorical question regarding "what did I have to lose except a $20 head" if it spins a cam bearing and seizes a cam then along with your $20 head you will lose your 1075 kit when it makes love to the valves that are stuck open

Wookie58 wrote:

SWest wrote:

So it can be done and I figured all I had to lose was time and a $20 junk head. 
I'm still using it today with my new 1075 kit installed and I'm RIDING THE PISS OUT OF IT.

Steve
. 

 

Steve I've gotta say it sounds like you got lucky with that one but it's not a solution I would advise anyone else to follow (what you do with your own is your business) We have all stripped motors and found things that make us wonder how they were still running !!!
Unless you honed it on a milling table I'm not sure how you maintained the hone at 90 degree's on 2 axis ?? So although the cam to bearing clearance may be in spec I don't see how there can be even clamping force on the back of the bearing shells so it's a bit of a lottery !!!
In answer to your retorical question regarding "what did I have to lose except a $20 head" if it spins a cam bearing and seizes a cam then along with your $20 head you will lose your 1075 kit when it makes love to the valves that are stuck open

I had been watching it closely for a year before I installed the 1075 kit. This has been done before with success on other motors. Granted the caps must be close or it wouldn't work. My friend Jeff has a shop and has done lots of things others wouldn't even try. I wouldn't suggest buying a head without matching caps and fitting them would be a crap shoot but it can be done obviously. 
BTW the wear patterns on the shell bearings are identical to the ones on my old head. I still plan on rebuilding it with larger valves or even J valves that are shorter than the KZ valves. With what I've learned I will put into the old head and keep RIDING THE PISS OUT OF IT, 
Steve

History is a guy had a Jaffa and an A. Jaffa when he got it had a blasted head on black motor. So thinking head was reconditioned. I bought the A off him in boxes and have restored to final engine assemble. The Jaffa tolerances app entry were on the loose side 008 but was advised to run with it. The A is hard tight with the caps torqued down. I can fathom that the previous builder had used the original A head on the Jaffa with the Jaffa cam caps thereby causing this problem now as his caps were way loose and mine now tight. He has since written the Jaffa off and wheel chair bound so not able to do cap swap.