motorcycles: Is it a mistake to buy a 1998 Harley Davidson Dyna with the 1340 Evolution motor rather than buying new?

1340 Evo motors are very good engines. I prefer them with big bore kits on them for torque though. Whether if buying a 98 is a good idea would depend on it's shape. A properly taken care of bike should give you many miles of service. Twin cams do run hot, but it's not that big a deal unless you sit in traffic a lot. A bigger issue is that early twin cams had problems with cam chain tensioners when the motors started getting high miles on them. A tensioner failure would cause the motor to grenade.

age? Doesnt matter. My daily ride right now is a 1971 FLH Electra Glide.

It will depend on the bike. You are talking about a bike older than many of the people that could legally ride it.

Yes

And doesn't matter the year of the HD

"Could the 1998 Dyna be a reliable runner?"

It could be. It could also be an utterly unreliable dog.

And that's the risk you take, when you are buying any bike that's almost 20 years old (not just Harleys...)

There's still a lot of those engines on the road.

How many miles on that bike? What's the price?

The 1340 Evo was a good engine. If it was taken care of you should be able to ride that about without issue.

Since u asking here, will NOT matter either way.

Running hot doesn't matter in Reality of HD