What to do to a 2009 Yz450f with 200+ hours?

Hey guys!! I got a 09 yz450f which is an absolute beast and has been such a reliable bike. the bike still starts first kick most of the time and its been running pretty good. Its got a Drd exhaust and a jd jetting kit.

So i took it out the other day and ill be nest it was feeling a little sluggish, like it didnt feel as snappy but maybe it was just me. But i clean my air filter every ride and oil with filter every 8-10 hours.

So heres my question, what would you guys replace motor wise since i got this much time on this beast. I definately need to check the valves but would i gain any power by throwing a top end in it? BTW i already have all the parts needed to do a top end. But if my valves are in spec should i replace them? I heard the intakes are usually good to replace but im no that sure.

BTW i ride woods and im getting ready to race this season!! But hey thanks so much for your time and i hope i can get this bike running as good as new again

thanks and god bless!!!


Split cases and do bottom end bearings and seals. New crank assembly. Inspect all gears and shift forks. New piston/rings. New timing chain. New valve seats and seals. At minimum on the clutch side, clutch plates but may need basket,etc depending on wear.

Time for a new piston and wrings and wrist pin for sure. If the head is still in spec I don't think you have to re do the valves, now.

yeah im definately going to be putting a top end in this week for the weekend. But will i notice really any difference in the power? Like i know its a 450 haha. But if the valves are in spec should i just replace em>? or just leave them be?

A new piston should make a noticeable increase in power and compression. Make sure to follow the manual as exactly as you can.

Ok i threw the new top end and it is running awesome. BUt it seems like it is leaking a little oil by the ignition cover and the oil is by the bottom of the cylinder by the filler cap. I check the bolts and they are tight but would it be better to replace that case gasket? We torqued everything to the manuals specifications as well.

Dumb question, but is the o-ring still on the filler cap?

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