crf 450 question

02-08 all swap

06+ has the best seat material. The 07-08 heads have the smaller exhuast valves, but still interchangeable back to 02

You can buy new heads with new SS valvetrain installed for like $550 ready to bolt on.

No not at all.

The cheapest route is to use the 04 TRX SS Intake valves and springs, and stock exhaust valves and springs (stock is SS). :

Intakes:

Valve, In 14711-HP1-670 2 each $ 20.19 = $ 40.38
Valve spring, In 14751-MEB-670 2 each $ 6.57 = $ 13.14
Valve Stem Seal 12209-KL4-005 2 each $ 4.82 = $ 9.64
Cotters, Int 14781-MEB-670 4 each $ 2.87 = $ 11.48
Retainer, In 14771-HP1-670 2 each $ 4.69 = $ 9.38

If you choose to reuse the exhaust valves, I would change these items at a minimum:

14782-MEB-670 2EA Ex SPRINGS $ 5.76
14772-MEB-670 2EA Ex RETAINERS $ 4.43
14781-MAT-000 4EA Ex COTTERS $ 2.18
12209-GB4-682 2EA Ex SEALS $ 4.06

Of course, changing the exhaust valves would be recommended. If you do them as well, you will need:

14721-MEB-670 2EA Ex Valves $ 32.82

or 2007 and later:

14721-MEN-A00 2EA EX Valves $ 31.99


Prices are not current, but give you an idea.

Changing valves, make sure the seats get cut. Sure saves 1 big headache later. Vintage Bob