Z1OwnersClub GB

Back in the pre-meltdown days I was having problems with the shims in my Z1R after lightly grinding the valves took the clearances below tollerance.

I needed some 1.90's but all the previously mentioned Yamahaha sources for this size had de-listed them (Kawasaki only list them down to 2.00).

Several folk spoke of grinding down shims and PaulJ kindly sent me three that had already been ground; albeit not to the 1.90 I needed so I could try a bit more grinding myself.

Errr.... nice idea but it didn't work.

Trying to grind the shims further using grinding paste on a glass sheet (to keep it all flat) does pretty much bugger all (yes I was working on the previous ground side!). After half an hours effort I had managed to clean up the grinding marks on one shim but made naff all difference to the thickness.

So; unless you have access to some mechanical surfacing grinding kit; don't bother trying to do it by hand.

What did I end up doing? Tipping the valves as suggested by Jerry(?) and detailed in the workshop manual got them back into the range where normal shims could be used.

Rufflel, a good point, however, before getting all your valves "tipped", it a good idea to check them in the head with cams to see you do not have to put a 300 (3mm) or greater shim in!

This check is carried out by assembling buckets and valves without springs, with say a 200 (2mm) shim in place and measuring the clearance, whilst apply pressure (by hand) on the valve head to the cam. Then measure the gap.

I say this, merely because, I once sent a set of valves to be faced & tipped and the machinist was a bit ambitious and machines too much off. Resulting in two things.... too bigger shims required and tops of valve collet had to be relieved. I now say, take a bare minimum off the tip.
RegardZ.

Good advice. I took about 0.2-0.3 off each valve so the ones that needed 1.90 went
to needing ~2.20's.

The workshop manual gives a minimum distance twixt the top of the valve and the
collett groove and I was well over that.

My big lesson learnt is that you should do a 'dry' build of the head on the bench
and check the cleanrances before bolting everything back onto the bike.