Re: Valve Clearances

[Eric Sheley <eric@xxxxxxxxxx>]

 ><< If the valve is loosing clearance then the seat must be moving
 >further toward the cam.  If that is the case then the head itself is the
 >problem.

At 02:02 AM 07/13/1999 -0400, TrmpetDave@xxxxxxx wrote:

 >I thought that a little tightening of the valves was normal in a new engine,
 >due to expected wear and tear, which is why the first valve clearance check
 >should be done fairly early in a high performance engine, which most
 >motorcycles have. Thinner shims, where required should cure it.

Dave,

You are correct in your statement that a little tightening of the valves is 
expected as the valves bed in (not so much wear and tear as a settling in). 
Once thinner shims are installed you should be all set until the next check 
where you would expect to find only a minor difference if any.

For all,

The problem that I see with our compilation of data at 6000 miles (or 
somewhere close to that) is that we are recording data that really doesn't 
tell us anything about the motor in question. We are taking 1 piece of data 
and from that we are assuming the beginning data and attempting to predict 
a result at some point in the future. Take a point on a piece of paper and 
see how many lines you can draw at different angles that go through that 
point (should be a lot more than one!). Now try the same thing with two 
points (drawing a line that goes through both) ..... It's rather crude 
example I know, but I hope you can see the point.

The first thing that we have to know is where the clearances were when the 
bike was delivered. As we don't know, we can't make any intelligent 
conclusions at 6000 miles other than whether they are currently out of spec 
or not. Also we cannot predict where the clearances will be at the 
recommended 12000 mile check. Just because a valve has the minimum .10 mm 
clearance at 6000 miles, we cannot say that it will be any different at 
12000. For all we know the bike was delivered with minimum clearance or 
dropped to .10 in the first 500 miles and hasn't moved any more in the 
following 5500 miles .......

Please don't get me wrong - I am not saying that there is not a problem 
here - I am only saying that we are reading far too much into a single 
piece of data.

Unless I have a performance problem (or hear a problem), I will wait to see 
what happens at 12000.

- - Eric




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