Valve Clearance questions

[Kev1R]

Bike 1978 Z1000 A2
Checked valve clearances and shims yesterday all are 0.05 to 0.10 as per the manual.
A lot of advice on here suggests aiming for slightly higher setting -

Q1– Does having the valve clearance nearer to .15 affect engine efficiency in any way?
(In my mind I see a greater gap means the valves are not pushed opened as far)
or is this simply to avoid making adjustments so often.

Q2 – One of my shims is 3.15. I understand the biggest shim size (that Kawasaki do) is 3.20. What happens after you reach the largest size - will this mean some work on the cylinder head?

Also - Does the club still do the shim exchange?

Many thanks

[zapo]

Kev,
Regarding Q2.
Over time the valve clearances reduce, so you have to put thinner shims in ..... not thicker ones.
In other words when the time comes, you will need a 310 or 305 - not a 320

Cheers

[zed1015]

The 0.05mm to 0.10mm figures are the old obsolete specs which were ammended to 0.10mm to 0.15mm due to instances of valve seat burning.
Never let them go below 0.10mm or set them at 0.10mm .
You must set them as close to 0.15mm as possible and if the next shim size takes you slightly above to 0.16mm - 0.17mm that's ok.
The wider clearances won't effect performance but the tighter ones risk valve damage and poor peformance when hot.
The clearances CLOSE UP over time not open so your 315 shim will need replaceing with a THINNER one if the clearance is too tight.

[Kev1R]

Thanks gents for tidying up my muddled thinking and also clarifying the background to the widely recommended higher clearances.
Now I just need to get 5 shims as 3 can be swapped around !

Cheers
Kevin

[Skid Mark]

While on the topic, will a wider gap at the time of lapping in new valves or after a rebuild result in the valves bedding in, where as when checking existing clearance there should be no significant change over short term?

[zed1015]

While on the topic, will a wider gap at the time of lapping in new valves or after a rebuild result in the valves bedding in, where as when checking existing clearance there should be no significant change over short term?

Regardless of the gap, new, recut or freshly lapped valves will settle slightly once run and should be re- checked after a few miles.

[Skid Mark]

While on the topic, will a wider gap at the time of lapping in new valves or after a rebuild result in the valves bedding in, where as when checking existing clearance there should be no significant change over short term?

Regardless of the gap, new, recut or freshly lapped valves will settle slightly once run and should be re- checked after a few miles.

Thank you, I should have been clearer it was the bedding in after tampering with valves I needed clarity on.