There is NO WAY a stock Seca 2 will do 140. About 115-120, which isn't bad.
the difference is the Yamaha is better
The spark plug gap in a Yamaha Seca is 1/2. It can be easily obtained and is very affordable and likely to be replaced by the owner. It is a quick replacement.
about 60
Change the oil.
SAE 20W40 type SE motor oil for > 40deg F SAE 10W30 type SE motor oil for < 60deg F
Idle speed will vary from 600-1000 rpm.Idle speed will vary from 600-1000 rpm.
What are the valve clearances on a 2001 Yamaha grizzly 600?
a diagram
32HP
one
50
BS30