How f***** am I?

Hi guys,

I am going to attempt to revive this thread as this summer my head gasket leak has gotten bad enough again that I can justify taking the head off again... it'll only be the third time I've done it in six years!

I am starting to suspect that the head is warped because new gaskets only seem to slow the leak until it gets worse again, btu that will be a problem for when I get it off.

I figured if thats gonna happen I might as well replace the two idler gears, the roller and the timing chain guide while I am in there. A long time ago, I found a fella who was making solid metal idler gears to replace the exorbitantly expensive NOS ones with the rubber in them. A precursory google search yielded nothing, so was hoping you guys might be able to point me in the right direction and jog my memory a bit. 

Whatever you do DO NOT have the head skimmed until you have checked that the cams will spin free when bolted back in the head on the bench with the valves etc removed .
Some of these heads develop a slight twist in their free state which straightens out once bolted back on.
If one of these "twisted" heads is skimmed the twist will remain in the cam journals when the head is refitted which will cause the cams to bind and destroy the shells etc.
 

   

Not one leak since!

You can still find the Liska style sprockets, tensioner, and top idler at KZZone.  The front guide looks to still be available from Z1Enterprises. 
Retro-motorcycles on Ebay has the front cam chain guide,small rubber damper blocks for the sprockets and for the lower roller.  KZZone has a handy diagram for reference.

zed1015 wrote:

Whatever you do DO NOT have the head skimmed until you have checked that the cams will spin free when bolted back in the head on the bench with the valves etc removed .
Some of these heads develop a slight twist in their free state which straightens out once bolted back on.
If one of these "twisted" heads is skimmed the twist will remain in the cam journals when the head is refitted which will cause the cams to bind and destroy the shells etc.

 

Very interesting observation.

Mama Kaw specs a test in the Z1 White Manual for "warp" (less than .25mm / 0.010 in.) with the suggestion to replace the head if warp exceeds the service limit.  Uh huh...

If a head was determined to have a warp / twist in its free state, does that mean it's not a candidate to be skimmed?  If skimming is possible, how would the machinist set up or jig the head?  Are the cams stiff enough to straighten the head sufficiently for skimming if they're bolted into their positions?

Good Ridin'
slmjim & Z1BEBE

slmjim+Z1BEBE wrote:

Very interesting observation.

Mama Kaw specs a test in the Z1 White Manual for "warp" (less than .25mm / 0.010 in.) with the suggestion to replace the head if warp exceeds the service limit.  Uh huh...

 Are the cams stiff enough to straighten the head sufficiently for skimming if they're bolted into their positions?

Good Ridin'
slmjim & Z1BEBE

The manual suggests replacing a warped head for the same reason.
If the head is warped then so is the cam journal alignment so they don't even mention skimming because the warp will remain in the journals. 
The cams won't pull the head straight or rectify the twist though. 
To skim one it would have to be bolted down on a thick precision ground steel fixture plate to pull it straight.
At a guess the plate would have to be a couple of inch thick and utilise all of the 32 m6 holes for the cam cover and cam caps which should be enough to do the job.
I've often thought of making a jig for this job to see if it would work but the cost of the plate alone was in the high hundreds and buying replacement heads was a cheaper option.