Valve clearances

[yorkie_chris]

Did a few bits on melodys curvy on sunday, checked clearances and all were within spec except for the front right exhaust valve, this showed less that 0.2mm but more than 0.15mm.
So, I would say this is worth changing the shim so as not to risk the valve, anyone think otherwise?
How much will a shim be?

Chris

[Sid Squid]

Do it.

About £5-£7 depending on who sells it to you.

Read me.

[yorkie_chris]

Right oh, dizzyblonde has a proper tensioner holding tool which makes life so much easier so shouldn't be too much trouble.
Any common pitfalls?

Originally Posted by yorkie_chris

Right oh, dizzyblonde has a proper tensioner holding tool which makes life so much easier so shouldn't be too much trouble.
Any common pitfalls?

How far 'in spec' were the others? I'd be inclined to replace them all whilst you are in there ... take them out to near max spec (largest gap) that way the job won't need doing again for ... well lets face it, the bike is already what 8 years old?!?! so probably ever (in Melody's ownership)

[rictus01]

Originally Posted by Blue_SV650S

How far 'in spec' were the others? I'd be inclined to replace them all whilst you are in there ... take them out to near max spec (largest gap) that way the job won't need doing again ... well lets face it, the bike is already what 8 years old?!?! so probably ever (in Melody's ownership)

whilst exhaust valve gaps do tend to close, inlets valves tend to open with wear, so setting them to the widest isn't wise.

Cheers Mark.

Originally Posted by rictus01

whilst exhaust valve gaps do tend to close, inlets valves tend to open with wear, so setting them to the widest isn't wise.

Cheers Mark.

are you sure?? How does that work?!!?

[yorkie_chris]

Inlet valves run cold (if CVH escorts are anything to go by) so the valvetrain wears more than the seats do, opening the clearances.

I only did a loose check i.e a 0.2 gauge fit, a 0.3 didn't (exhaust valves) so not a clue what the rest are at with regards to how far each way they are

Originally Posted by yorkie_chris

Inlet valves run cold (if CVH escorts are anything to go by) so the valvetrain wears more than the seats do, opening the clearances.

I only did a loose check i.e a 0.2 gauge fit, a 0.3 didn't (exhaust valves) so not a clue what the rest are at with regards to how far each way they are

Still not convinced ... surely what causes the wear is the valves smacking into the head ... and the inlets have higher lift ... sure the heat of the ex might accelerate wear, but the inlets still get a hammering ...

I have done quite a few bike valve clearances over the years ... and I have NEVER had a gap go LARGER than spec (inlet or exhaust) ... not since days of tappets anyway ... well with the exception of when I have a bent valve ... that gap was pretty big!!

I suggest someone do a bit of googlefu to confirm or deny the allegation that gaps get larger (on bucket and shim OHC) ... I am not convinced that is the case - if for no other reason than through observation ...

[yorkie_chris]

I'm not too fussed either way, if I bother with more than 1 shim then I'll set them to the middle of their adjustment as they can go both ways.
Have seen them go tight and loose so will hedge my bets and put them halfway, if a little loose as thats the safer bet.

[rictus01]

Originally Posted by Blue_SV650S

...

yes it's right, whether you're convinced or not , understanding the thermal dynamic wear pattern on the different valve trains explains it quite logically, look it up, and I have seen valve gaps greater than spec.

but then you do post for effect, so it doesn't surprise me.

Cheers Mark.