Z1OwnersClub GB

Can anyone identify the pistons ?
The numbers dont seem to be Wiseco

Stuart
shims are under bucket on unitrack heads so it is correct
unusual to see broken shims
I had a smashed shim on a Z1 engine recently and a badly fitting bucket caused it
it would not compress when cam lobe struck it so something had to give and the shim shattered

paul doran wrote:unusual to see broken shims

I read somewhere (maybe on this forum?) that some people ground old shims down to a smaller size rather than buying new ones, and this was likely to effect their "hardness" and cause them to break.
Could be the cause, or an old wive's tale?!

I had a similar problem on my ELR, the stripped threads were over come by getting an engineering co. to install brass/bronze stud then mill flat and driil and tap to m6.

The lack of compression on mine was turned out to be partly down to a cracked valve guide, all guides then got replaced and head rebuilt with HD A.P.E springs as it gives me the optiom of hotter cams in future if i desire or deemed needed.

Just a thought ..... have they used the correct valve spring retainers for the shim under bucket ?
I believe they are different to the shim over bucket ones and maybe that broke the shims
I will stand corrected if that is not the case that they are different