Just a quick question regarding the valve clearance settings. is it better to adjust the valve clearance to the tighter side or the loose side of the specification range?

You'll get many different views and opinions on this on this one I'm sure!

For me personally, I always set them at the looser end of the range. Why? Because valves clearances close up over time and a tight valve is much more damaging than a loose one, so I like to give a little room for this. Plus, with screw and lock nut adjusters, I always find that no matter how hard you try to hold the screw while you tighten the lock nut, it'll always nip up a fraction further than you had it set.

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Great. But why then would others adjust to the tighter end of the range? As far as I can see this would be counter productive, not only potentially damaging but also shorten the adjustment period?
Are there performance benefits? Again common sense tells me the opposite would be true as the capacity would be reduced?

I guess one might err on the tighter side of the acceptable range because of wanting a quiet, less "tappety" engine. The risk is, as you suggest, that as the valve seats regress, they will become over-tight sooner as there is no room, or spare capacity to allow for this.

Anywhere within tolerance will not be detrimental to performance, only if the motor runs outside the clearance range will issues occur.

Some of the symptoms associated with tight valves:

They won't close properly, resulting in loss of compression and power and there is a risk of burnt/melted exhaust valves and engine damage. Poor starting and rough running, particularly at tick-over. Worse economy. The top end will run quiet.

Some of the symptoms associated with loose valves:

The valves won't open fully, so exhaust gases won't be scavenged properly on the exhaust stroke and a full charge of fuel/air may not be drawn in on the induction stroke, all meaning a loss of power. Poor running at higher revs. Worse economy. The top end will be noisy.

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I remember reading somewhere that it is possible to adjust the exhaust valve clearance without removing the radiator or draining the radiator. How is this possible?

Undo the radiator mounts & move it forward leave the coolant pipes on & cooling system full no need to drain it.

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My 04 XTX
Stage 1 & 2 DNA filters / Kev fuel mod / snorkel mod / Drilled air box mod / Engine breather mod / Fork Spacer mod / 15w fork oil /
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My 07 XTX
Raptor 700 cylinder 102mm / Modified Crank Case to take a 105mm Raptor Cylinder / 11:1 102mm JE Raptor piston / Stage 1 Raptor Hot Cam / Ported head / Colder Spark Plug / +2mm Throttle body / DNA stage 1 & 2 filters / Modified Air Box / Snorkel removed / Worry Brothers stage 2 filter cover / 6mm & 8mm Bolts Replaced with Titanium Bolts / Recovered seat in Black / O2 Eliminator /

My 09 XTX
59HP at the rear wheel / Stage 2 Raptor Hot Cam / DNA stage 3 Air Box / Carbon Can Exhausts / Modified Exhaust Link Pipes / PCIII With Custom Fuel Map / Wideband Commander O2 Data logger / LCD100 Dyno Jet display & fuel adjuster / 2500 OHM HT lead instead of a 10K OHM XT lead / Extra Coolant Cooler / Protaper Fat Bars / Tail Tidy With LED Tail Light / OKE Protection Knobs / LED indicators / AIS blocked / Modified rear sprocket rubbers / Rear Foot Pegs removed / 09 ECU With 02 Sensor Changed To A 06 ECU / Complete wiring harnes Changed from 09 to 04 / Home made LED resistor flasher / Hole drilled in the fuel tank filler neck to allow quicker filling / Modified Bar End Weights / Progressive front fork springs, 15W fork oil, forks lowered 25mm, used XTR rear links lowering the rear 20mm, rear spring one click stiffer / Changed front & rear guards from blue to black / 47T rear sprocket / Speedo Healer V4.0 / Kev throttle cam mod / Throttle grip mod / The new 2010 O2 sensor mod is out, works a treat, The new 2012 O2 Controller is out, PM me for details

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+1 No need to remove radiator on the Z as Kev says. There is enough flexibility in the hoses to get the room you need, but you do need to be fairly dextrous!

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Managed to get it done in the dark with a torch. Not without event though, one of my sprocket cover bolts broke of in the hole.
The hardest thing was getting the feel for the clearance with the feeler, and I'm still not sure if it's correct or not. The clearance seemed way out on both the intake and exhaust

I think I have over loosened my exhaust valves. The power output is okay but there is a clear tapping noise coming from the engine.
I'm i okay to leave as is?

This is doing my head in, I really can't be sure if the sound was there before or if it is an okay sound.

How are things now? Has it settled in or are you still concerned?

I'd just like to ask what your mileage is? And what prompted you to do the clearances.

I'm at 14,500 miles now and i know for a FACT that valve clearances weren't done by my dealer at my 12,000 mile service (but they should have been!).
So I'm thinking of doing it myself... probably this week if I order new O-rings.

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