i just bought a 2002 yamaha yz426f and the motor locked up on me. i took it to a dealer and they said the timming skipped and a valve broke and ruied the piston and damaged the crankcase. wondering if this is worth fixing. it was bought new in 2005 so it hasnt been rode to long. at the dealer they said these bikes have a poorly built motor is this true. is this bike not worth fixing and do they have to be rebuilt a lot. a could not find an engine for sale any where. also wodering if a wr426f motor would fit on my yz426f. i bought it for $2100 and only rode it twice before it locked up. it was a huge dissapointment for me and want to get back out ridding. any advice would be much appreciated. the dealer told me they wanted about $5000 to fix and i felt like crying like a baby.