info needed on an 03 yz450f

7 replies to this topic
  • 2-stroker

Posted July 18, 2008 - 06:31 AM


hi, im selling my 125 smoker and looking at a 2003 yz450f. can you give me the good and bad on this year and some stuff i should look for on the bike? the guy said it has low hours and the valves are in spec. but doesnt know the exact hours. it is bone stock btw. also im goin to run a compression check on it, what should the gauge read in PSI. heres a link to the bike:http://delaware.crai.../744833887.html

  • grayracer513

Posted July 18, 2008 - 06:38 AM


You can't run an effective old school compression check on any engine such as the YZ450 that is equipped with automatic decompression. If you did, you would only see about 100-130 pounds. Besides, if it were a manually decompressed 426, for instance, most people can't kick them through a full compression stroke.

What you need is a leak down test.

  • 2-stroker

Posted July 18, 2008 - 06:51 AM


well i cant do a leak down, so what should i do then? just take the chances and buy it?

  • grayracer513

Posted July 18, 2008 - 07:45 AM


If the compression stroke feels solid against the kick starter, and the engine doesn't quickly leak through it when you hold pressure on the crank, it's probably OK for now.

The '03 was an essentially very solid bike with an uncommon level of reliability. Even though I have come to take it somewhat for granted, I still find myself amazed by how well the YZ450 holds up, considering what they do. Mine had well over 375 hours on it when I sold it, and never had any more than a timing chain replaced for maintenance. But, they are not indestructible.

Ask your seller how often he changes oil, oil filters, and cleans his air filter. The correct answers would be no less than every third ride, filter with each change, and air filter AT LEAST every second ride. Ask when the steering head and rear linkages were last greased. Has the timing chain ever been replaced?

If you can ride the bike any distance safely, check that it will stay in all four gears under a load. If it jerks or skips in one gear only, pass it up or get a fat discount.

The '03 was a very snappy engine. It's low speed power delivery was so abrupt that people were saying that it was too much like a two stroke, and found it hard to manage. It's not that bad, but there's some truth to it. A heavier flywheel helps this.

The '03 has a smaller rod bearing than the later models, and while they are definitely not weak, they do very occasionally break the bearing cage, which locks the rod. There is no way to see this coming.

The '03 was the last year the YZ's had the 46mm fork. The '04 had an open bath 48 that is now used on the WR, and the '05 had the first of the twin chamber KYB's. The '03 fork is not the best, and not equal to any Showa fork the same year, but they aren't awful, and you can work with them

They are lighter and more nimble than a 426, but less so than an '06. Overall, for the right price, they can be a pretty good buy.

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  • 2-stroker

Posted July 18, 2008 - 08:01 AM


yea the guy said he will take 1800. if it looks really nice ill give him 1800, but if its not what i expected ill try and get him down to 1600.

  • 2-stroker

Posted July 18, 2008 - 08:20 AM


i just called the guy, he said he only rode it about 4 times, changed oil twice along with filter. cleaned air filter every ride. he races his 2-stroke and seems to know what hes talking about. said he greased all the bearings, i didnt even get to ask him if he did he just told me. i might head dows there to look at it sunday.

  • Ga450owner

Posted July 18, 2008 - 10:05 AM


Wow it must be 03 week..........look at all recent 03 threads past 2 days..for more info.

  • lluks252

Posted July 18, 2008 - 04:47 PM


Ya I bought my 2003 YZ450F for 2,000 with 50 hours, 2 sets of plastics (blue & retro yellow) Hinson clutch, White Brothers top triple clamp, & front forks are tuned by an expert around here that owns his own tracks called EURO Raceway

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