Firstly - hello to all. I'm not just here to milk knowledge but will hope to pass on what I learn concisely. I have a question: Today I got into the guts of my 999S to give it the once-over. The bike has just under 10,000 miles on it with full main dealer service history; but if there's one thing I've learned over the years; it's that I like to make my own checks. That being the case - here are my measurements: Now I don't have the experience many of you have (that's why I'm on here) - so would like your interpretations of my results and what I ought to do. I believe that altering a closer shim will affect its' respective opening shim (and vice-versa). How can I accommodate for this? Many thanks for anybody's help in advance - I'm eager to learn, eager to do it right - and happy to listen! Best wishes, Rich
Looking at you actual measurements, they are all in tolerance. You don't need to adjust any of them. Adjusting a closer, won't affect the opening gap. Its always good practice to double check everything before you refit the covers though, but it shouldn't change.
Cheers Nelly, I guess that the shims at bottom limit have loads of life left in them? As for the one at 0.23mm - I'm wondering how much life that has left in it before it requires attention? I guess I can work on a worst-case scenario and work out the wear rate over the mileage done...
Based on that assumption, I guess we can work out the worst-case rate of wear for the closer which measures at 0.23mm 0.23-0.18 (measured - max. Assembly value) = 0.05mm 0.05mm / 10,000 (possible wear / mileage) = 0.000005mm per mile Difference between measured value and max. permissible value = 0.02mm 0.02mm / 0.000005 = 4000 miles. My maths is bloody awful but think this is right(?) However, the 0.23mm figure falls within the manufactured value so that might not have worn at all either(?!) Sod it, it's all going back together and I'll check on it in 4000 miles time!
To do that calculation properly, assuming linear wear rate, you'd need to work out the number of revs that have been accrued per mile...plus factor in the heat effects. Nasty job...still, good to see some logical thinking behind the "fuck it, put it back together!" decision!
Thanks guys - yep, new belts are being installed. Cheers for the advice - noted that Nelly knows his stuff! Rich
Don't forget, tappet clearances can go up and down (stem stretch / seat impaction / wear & tear) and if I remember correctly, the opening clearance must be "taken up" before the closing clearance is measured, adjusting one does not affect the other.
Once an engine has been used, there might be some carbon particles on the valve seats or there might not be depending on the way the bike has been ridden and the fuel settings, etc. If there are carbon particles present, they may make the closing clearances look a bit tight and the opening clearances look a bit wide. It would be a mistake to alter the shimming on this account, as the carbon might disappear again with later use. That's my opinion, anyway.
