It may seem that way, but at least on those engines I have SEEN it, it happened. The valves are typically at 1200-1500 degrees. The cylinders are a mere 3-500 max. As I said, I am not sure about motorcycle engines, but for want of a properly attached flange, is it worth the risk?
Where I have seen it the most is in an air cooled engine. When I get back home, if you doubt me, I can post a pic of the last valve I removed. Though I do not have a pic of the exhaust flange that cracked to cause the problem. I have seen cylinders that cracked because the power was reduced too quickly, especially in rain, with no other problem! So, yes, temp changes can definitely crack a cylinder or a valve. -- You received this message because you are subscribed to the Google Groups "Nighthawk Motorcycle Lovers!" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/nighthawk_lovers. For more options, visit https://groups.google.com/d/optout.
