I posted this on the Valve "Clearance Guide" sticky but I dont think anybody would have noticed it (as its sticky)

So here we go again ....

Ok so I have measured my valve clearances and “most” of my clearances are right on the lower edge, which is to say 0.12(IN) and 0.21(EX) respectively.

They are all technically in range, I get that. I don’t HAVE to change the shims because as I understand it these tolerances will get tighter over time i.e. fall out or range and become something like 0.11(IN) and 0.20(EX) possibly smaller.

However my though process goes like this:-

If I replace the shims on these values now with shims that are 0.05 thinner than the currently installed shims the clearances will become 0.17(IN) and 0.26(EX) which are still in range but with the advantage that the next time I check the clearances in another 10,000km time will they will (probably) give me clearances that have tightened up but are still in range.

This should mean:-
A) Next time it’s just a check clearances and leave alone  (Most likely)
B) If I leave as is for now there is a good chance that the clearances will fall below range before my next 10,000km. If I do it now they will be “optimal” all the way to the next service.

OK Guys go nuts, let’s hear your thoughts on my thoughts

If they are in spec, they are in spec. It all comes down to how OCD you are about them. Personally, I would change them. But that is because I already have shims on hand, and I'm already in there. Plus there is the peace of mind knowing that they are still probably in spec 8,000 km down the road.

Thanks vfrman, thats kind of the way I'm thinking.

It's apart already and I'm in no particular rush to put it back together, best to "do it right" for the sake of a few quids worth of shims.

Indeed. It's hard to put a price on peace of mind.

st22041967 wrote:Thanks vfrman, thats kind of the way I'm thinking.

It's apart already and I'm in no particular rush to put it back together, best to "do it right" for the sake of a few quids worth of shims.

yeah id change them if your in there too. and make a note of what is in where and dont loose it so you dont have to re-measure next time.

8000km isnt a great distance, i doubt theyd tighten up too severly.. even if they are very slightly tight you wont often cause any damage unless they get stupidly tight.

one of the bikes i bought had an inlet of 0.06mm when on that engine the minimum was 0.14.. was still running fine according to the previous owner but i get them all sorted out anyway.

i tend to set them towards to loose end if i have chioce of shims.. i believe Honda set them dead in the middle at the facotry.

Just as a follow up.

Bought shims from wemoto. Job was a pig and I dropped the shims many,many times. However rags and magnets in the correct places prevented disaster! So in summary Excellent value, correct sizes and quality service. Just spreading the love........

http://www.wemoto.com

Ok one last thing. How tight should the cylinder head cover bolts be (The ones that secure the valve covers and which go through large rubber washer/bushes)? The manual says 10Newtons but I'm actually scared to tighten them up that much as it seems very tight even before the torque wrench goes "click".

PS wrench is calibrated correctly.

this part (Number 7)

https://www.fowlersparts.co.uk/parts/view/90002ML0000

off hand i believe mine were torqued up to about 6nm

there shouldered bolts so just turn them till they stop and tighten a little by hand with a wrench and they will be fine.

only toqured last time as i had the torque wrench in hand from doign cams

That's what I thought, cheers neosophist