Hi Guys, I'm currently attempting to do the valve adjustments on my hypermotard 796 however I've run into an issue. How do you hold the valve to prevent it from falling into the cylinder whilst removing the closer shims? I initially tried to secure it with safety wire however the valve would just slip through whilst depressing the rocker so I decided to purchase a set of forceps to use as per the CA Cycleworks video, I got the forceps through the post today and attempted to use them to hold the valve however I can't get an angle on the valve stem. If I were to remove the belts and set the piston to TDC would that prevent the valve from falling too far into the cylinder? Cheers!
You must always have cylinder you are working on at TDC then there is no chance of a valve falling in. The valves will fall down until they touch the piston crown but that will be too far to allow the shim to be moved down far enough to get the half rings out. I use a pair of forceps with a 45 degree crank at jaws to hold the valve. There is bit of a knack to it but it gets easier with practice.
I always do valve adjustments with the belts off, that way not only can you use the piston to 'hold' the valve but you can feel how tight 'tight' is when setting tight closer clearances. But apart from all that it makes the job easier as you don't need to keep turning the engine...
I read somewhere that feeding string through the plug hole and then gently bring ing the piston up till it stops holds the valves in place
I took the belts off again last night as I couldn't see myself getting any forceps to work for the tight space. I tested spinning the cam around and was surprised at how much tension the desmo springs give, I needed two hands to rotate the cam and even then it was quite difficult. I know that my closers aren't binding right now as they're both at 0.06mm clearance, I presume if they're binding after the adjustment the cam would be near impossible to rotate? Unfortunately I don't have time to do the rest of the adjustment right now but thank you for the help everybody!
The springs are actually quite strong. The beauty of having no belts is that you can check exactly how tight that closer gap is: You have measured 0.06mm so, if you put a 0.06mm feeler in the measuring gap, thus taking up the closer clearance, then the whilst rotating the cam by hand you will feel it bind. If it doesn't bind then your clearance is more than 0.06mm, alternatively it may bind at 0.05mm etc. - You won't feel this by turning the engine with the belts fitted.
Ah that seems like a fantastic method, I'm always a bit sceptical about my feeler gauge measuring skills so this'll definitely help give me more confidence. Thank you!
Reading this in the light of day (and not straight after having finished a bottle of wine) to feel closer drag you would also need to take up the opener clearance first, (unless you can get a feeler into closer rocker/cam interface?) so if closer is 0.06mm and opener is 0.1mm then you'd need the 0.16 feeler to make it tight. E.g. I have a spare S4 head on the bench to which I've just fitted a valve/cam, not worried about clearances being to spec so I've stuck in the first shims that came to hand and I have 0.22mm opener and 0.30 when rocker loaded = 0.08 closer. If I turn it with the 0.22mm feeler in it, it is tight when opener is on the cam but no tighter when the closer is on the cam, if I stick a 0.30 in it then it is tight all the while, a 0.25 makes it tight during opening and just starting to feel tighter on closing. I like to be able to feel that the closer is as close to 0 as possible without binding but also to know how close (within reason), and definitely no more than 0.05mm. I'm not suggesting it's how to set clearances but I find it useful as a double-check, especially for the occasions where you measure one reading and then get a slightly different number when double-checking it.
