Just checked my valve clearances and all but a couple of them are slightly (0.01 to 0.04) out of tolerance on the tight side called the guy who I bought the bike off and he admitted to not having done them in the 40,000 km that he put on the bike. I've pulled most of the shims, but they're all within 0.02-0.04 of each other, so could only get a couple of valves just barely back into tolerance, would much rather have some room to play with so I'm just going to replace the lot. I noticed the ones listed on ebay that were mentioned in one of the other threads, does anyone have any experience with them?

http://cgi.ebay.co.uk/16-x-VALVE-SHIMS- ... 35a6d61db0" onclick="window.open(this.href);return false;

I've also been thinking about pulling the heads off so I can take look at the bores, head and valves/seats. If I'm replacing all the shims then this would be the perfect time if the valves need a little bit of grinding so that seems like a good idea. Lets me catch any damage that my recent track day on the tight clearances might have done. Good for some peace of mind.

So, this leads me to my main concern: The Haynes manual makes a big deal about replacing the Rocker Shaft Plugs with new ones if you remove the rockers but I can't find a part number or listing for them anywhere. Would it be possible to just flip the rockers up and out of the way in order to remove the valves? Edit: This is possible and the easiest way to do it, just needs a piece of 4x2 to sit the head on while working on it.

Also, is there any trick with replacing the shims on the front bank, the rear bank was easy but the front took ages. I'm wondering if maybe it would just be easier to lift the cams, swap the shims and then drop the cams back in?

There is supposed to be a bit of room to slide the feeler gauge under the cam lobe easily, it shouldnt be tight. Are you sure you are measuring them correctly ?

If they are all the same it would suggest somebody has replaced them all. You may find running some fuel system cleaner through with the petrol may burn off any deposits on the valve seats and give a little more tolerance at the shim.

Yes you can lift the rockers up ,I have removed the shafts and rebuilt the heads using the old plugs,no problems for me.

@Old Painless: Sorry, should have been clearer about that. It wasn't that the clearances were 0.01-0.04mm, they were outside tolerance by that much. For example, most of my inlet valves were 0.08-0.12mm and exhaust valves were 0.17-0.21mm. This was checked with a set of imperial feeler gauges down to the nearest 0.0005" (0.013mm) by combining pairs of leaves and checking between the rocker arm and the shim itself. The 14 shims that I checked were mostly 2.22-2.28mm when measured with a set of digital calipers, but these combinations only let me get near the middle of the tolerance range on a couple of cylinders. I didn't check the last 2 exhaust valve shims on the front bank because it was a pretty grim job getting the other front cylinder's shims back in, my garage doesn't have particularly good light.

@hunter: Good to know, thanks! Did you use anything like loctite on the plugs or just put them in dry? Can you think of any reason why I would have to remove the rockers to pull and grind the valves?

I would try a metric feeler gauge and try again, you might be doing unnecessary work as your measuring is not accurate due to the difference between the metric and imperial gauges.

If your 0.01mm under and your measuring to 0.013mm tollerence ?

I'm probably wrong and your doing it just fine. Sorry to be pedantic.

It's all good, happy to have someone throwing ideas at me!

I'm measuring to a 0.013mm resolution, I should have said. If I could find a decent set of metric feeler gauges, believe me I would be using them. I've got 2 sets now and both are imperial, it's pretty horrific.

This is how it converts:
thousandths - mm
2.5 - 0.064
3.0 - 0.076
3.5 - 0.089
4.0 - 0.102
4.5 - 0.114
5.0 - 0.127
5.5 - 0.140
6.0 - 0.152
6.5 - 0.165
7.0 - 0.178
7.5 - 0.191
8.0 - 0.203
8.5 - 0.216
9.0 - 0.229

So 0.01 under means the 5.0 was a no-go while the 4.5 was a go, so the actual clearance is somewhere between 0.114-0.127... That valve could probably be considered still within tolerance, for sure. However the 0.04 under means 3.5 was a no-go while 3.0 was a go, or 0.076-0.089. Even an optimistic 0.088 is WAY outside tolerance

You could get metric feeler gauges from a thousand places on ebay or a local motor factors supplier. Google may be a good bet. Mine were £5 i think, better than a big mechanics bill, not that i have anything but the utmost respect for mechanics.

Mine wont do the exact minimum tolerance in the manual but they can get me within min/max spec well enough. A couple of hundredths over minimum is more than okay for me.

You must be doing a load of maths to find out what measurement you have got, then more to find out what you want and then more to see what you need to change. You have guts and determination if nothing else.

Thanks :) I'm an electrical engineer and my last job was mostly printed circuit board design, both of which require a lot of maths and a lot of bouncing between metric and imperial, depressingly enough.

I had another look for the gauges, they're about 20 pounds for a cheap unbranded set here, but it's a bastard to find someone who actually stocks them and will sell without an account. One of the ones listed shows the photo of the gauge marked in mm but from the imperial thickness leaves... Bah... Will just e-mail one of them and see what happens.

I got a set of feelers of flebay. draper ones, and they have both metric and imperial on. cost me £7.50 +pp.
I just lapped in the valves on my nc35 heads and left the rocker arms in. I just lay the head on its side and with somthing behind it to push against and it seemed fine. you just have to be careful not to get any grinding paste on/in the springs or the rocker shaft. And get a decent lapping in stick as i have tried 2 and both are shit.

Good advice skinnydog, cheers.

Got a nice set of metric feeler gauges in front of me now, found a set for the equivalent of 10 quid shipped from a new engineering supplies website in NZ... They also stock Mitutoyo calipers and micrometers, which I've always wanted a set of... Dangerous place to be looking at for too long...