If you truly want a 660 Raptor to last a long time, leave it stock or only piped and jetted.

 

it will run fine, its got the carillo in it, i take it your buying this used. fund out if that had they crank balanced when they put the new rod in, and if they did....what rpm did they balance it for. i will tell you why i would not buyt this bike. the ported intake valve to a +3 over? ive never even head this. a 727 runs really stong on +1 oversized valve. check into the valves and the rod before anything. compression on piston is safe also. find out who build all this stuff also.

 

Compression is good, the bike was built by mac racing out of salem, OR I had local yama shop look at it they said it was fine, the only strange thing that happened is when we started it up it blew carb boots of onece. That , plus sometimes when shut of makes "klunk" sound is that bad?

 

If it's an 01 Raptor, the carbs were more prone to blowing off due to the weak intake boot design. These boots were updated for 02 and work fine on an 01 bike. The true fix is richening up the idle circuit. That clunk sound is more than likely the counterbalancer coming to rest....all raptors have a small clunk upon shutdown.
Gary

 

but what about the size of those valves???

 

I would take it to another custom builder to have it checked. If the guys at the "local yamaha shop" were competent enough to check a builders work, he would be a builder and not a warranty guy. Having said that, I agree, what is the deal with the valves? Are you familiar with raptors/ Stock, slightly modded, modded, and heavily modded like the one your looking for? I ask only because I think YOU should have a baseline to compare to.