2003 yz450

I am considering trading an old nighthawk 700s for an 03 yz450. Are there any known problems i should look out for? Are the engines noisy? I ask that because i have a drz400 and it has always rattled a bit. Common problems? Thanks in advance.

Even though when compared with other dirt bikes the '03 YZ450 was an exceptionally reliable piece (mine went over 4 full years with nothing more than spark plugs, oil changes, and 3 timing chains for maintenance), there are things Yamaha upgrade on the '04 that do occasionally turn up as problems. 


The kick starter assembly was upgraded, as it had a tendency toward breaking internally, and this sometimes damages the crankcase.


The connecting rod bearing was upgrade to reduce problems with the roller cage breaking and locking the engine up. 


Neither of these was ever a "common" problem, just something that happens now and then.

I've heard you talk about the kick starter in other threads. Which part in particular is the problem - the shaft, gear or the pawl assembly? I plan to install a wr trans shortly and put a new rod / rod bearing in for safety and if I need to replace or inspect something in the kickstart assembly please let me know. Thanks for all the great advice / knowledge you give. Clay

Pretty much the whole thing as an assembly.  I'm not sure what the weak link in it was, but I have seen people report broken shafts, pawls, and gears.  The entire unit was upgraded around the time of the release of the '04 model, and even the kick crank itself was beefed up.  The original parts haven't been available for some time, and none of the individual pieces for the new one fit the old.

I love mine !! Bought it in a basket reassembled it with as many oem parts as needed .. threw away the auto tensor .. they fail ! if 4 stroke is loud and ticky buy a cam chain people neglect that as gen maintenance.. my 03 with stock water pump and stock rads got hot trail bashen   so i upgraded the water pump to high flow and gti over sized rads were like 80 bucks on ebay  .. change the oil keep eye on valves dont neglect maintenance should be a good bike and last a long time .. be shure to go over it with a fine tooth comb usually people rig stough to trade before it goes boom ..   

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