TDC / Valve Adjustment Questions

 Weather permitting, will be doing valve adjustment this weekend (2006 Honda
Shadow 600).  First time.  Ever.

Questions:

a)My mental model is that the crankshaft probably goes around twice while
the camshaft goes around once?  Correct?

b)What is the easiest way for me to determine TDC on the compression stroke?

There are marks on the flywheel or crankshaft for positioning, but I'm
guessing that lining up the mark gives me a 50/50 as to compression stroke
or exhaust stroke.

What is the easiest way to tell compression stroke and exhaust stroke apart?
Should I watch the valves as I rotate the crankshaft?  Or is there some real
easy way that I'm not aware of?

The Lizard

 

At TDC on compression, both intake and exhaust valves will have some
clearance.

 George R. Young wrote:


Yes, as long as neither is out of adjustment on the tight side, but the
principle is correct.

--
sjs

 

One would hope :-)


--
Beav

VN 750
Zed 1000
OMF# 19

 wrote:


Not all engines set the valves at TDC.  Make sure the specs are for TDC or
whatever marking is correct.  Some like my Kaw set by aligning marks on the cam
sprockets with the head surface which is definitely not TDC for either of the
valves checked at that point.  In any case, when the piston is at TDC on the
compression stroke, you should have clearance in both the intake and exhaust
valves.  If it is the exhaust stroke, one or both the valves will be at least
partially open with no clearance.  You can probably observe this as you rotate
the crank.  I suspect you have little experience using a clearance guage (feeler
guage).  It takes a bit of experience to get the "feel" of a correctly set
valve.  I suggest you use either a go/no go guage or two separate ones.  Using
this method while get you an accurate setting.  The correct setting should slip
in nicely.  The next thicker one should not go in.  You should be well within
any specs doing that.  The worst case for setting valve is not enouigh clearance
which may result in a leaky valve or not enough on-seat time for proper cooling
which may result in a burned valve.  A valve too loose may result in noticeable
reduced power and fuel economy but is preferred to being too tight since excess
valve noise is usually the biggest offense of being too loose.  I suggest you
check the clearance with the go/no go method before changing any setting.  If it
passes that, don't screw around with something that you may make worse by
adjusting.

Good luck

Lugnut