Hi Jake,

It's usually pretty easy to tell... you're suddenly down 1/4 the
usual horsepower.

You can determine which cylinder it is by pulling off spark plug
wires until you identify the one that has no effect on the engine
when you remove it. Once you verify that it isn't a spark or fuel
flow issue you can test compression to know for certain what's going on.

CHT will climb MUCH faster than oil temps. It's not hard to get the
heads up to 450 on a hill at 65MPH if you've been cruising at 65 for
a while. Oil temp will typically lag the CHT for several minutes
before catching up, so unless it's a long hill the oil temp gauge may
not even notice, even if the CHT is well into the red zone.

Happy Trails,

Greg Potts
1973/74/77/79 Westfakia "Bob The Tomato
www.pottsfamily.ca

On 25-Jan-07, at 8:38 AM, Jake Beaulieu wrote:

> So what are the symptoms of a popped valve seat on an air cooled
> engine?
>
> For those of you that have both an oil temp gauge and an cylinder head
> temp (CHT) gauge installed on an air cooled motor; do the temperatures
> track eachother closely?  Some argue that the oil temp should be kept
> below 225, if my oil temp gauge never exceeds this limit does that
> pretty
> much guarntee that the cylinder head never exceeds, say 400.  Or
> can the
> CHT be too high while the oil remains at an acceptable temp, or
> vice versa
> for that matter?
>
> jake
> 82 AC Westy