yz250f Athena questions

[norwegn]

I am thinking of putting the Athena 290 kit on my 05 yz250f. The questions I can't seem to find answers on are:
1) If I put the 290 kit on, do I have to upgrade the valves and springs as well?
2) If I don't, how reliable will the motor be?

I am not a hardcore racer by any means, only 4-6 times on a good year. I just like to ride 1-2 times per week if i can. I am just worried about having the motor grenade on me.

Thanks for any help you can provide.

 

[steve125]

http://dirtrider.net/forums3/showthread.php?t=124155

 

[Rich Rohrich]

I am thinking of putting the Athena 290 kit on my 05 yz250f. The questions I can't seem to find answers on are:
1) If I put the 290 kit on, do I have to upgrade the valves and springs as well?

If they are worn YES,

2) If I don't, how reliable will the motor be?

If the valves and springs are worn the engine will be unreliable regardless of the size of the bore. If you don't have a lot of hours on the engine then valves and springs should be fine.

290 kits will make more power at lower rpm, so they tend to last longer than comparable OEM parts, and tend to be easier on the valvetrain due to the lower sustained rpm.