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Discussion Starter #1
i just got an 03 yz450, and i was wondering if there are any weak points on these bikes? an wondering how hard i can be on the bike...etc
 

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suspension is soft, brakes need upgrading (if you haven't yet), needs exhaust system for smoother power, gearing- 14/41 since it has a 4 speed.

Oiling to the clutch needs improving. I had my basket drilled out for more oil flow.

I got on a dynojet 50.3 rear wheel hp and 34lb ft of tq.

Wish it was street legal. Fun bike though. I use mine for track days as a dedicated track bike.

Good luck!
 

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i just got an 03 yz450, and i was wondering if there are any weak points on these bikes? an wondering how hard i can be on the bike...etc

be as hard as you want on it. its an MX bike its kinda intedned to take some abuse.

as rev said SM valving is a good idea

the 03s are supposed to be 'the year' for the 450 motors...they have evidentally been 'detuning' the hit out of it and making it smoother in years since...

If your hotstart works now, pull it apart and do a super light coat of anti-sieze on the plunger...the difference in metals can sieze the plunger into it (either open or closed or partial)

Honestly on thumpertalk they have a good 4 stroke YZ section that covers alot of probs/questions...and anything that greyracer says, listen to...hes smart
 

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and abuse they like. I've heard about the '03's being the "ONEs".
 

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Im new to the oiling prob you talk about...the only problem Iv ever had with clutch is super mega hella chatter when we practised starts for 20mins straight...i let it cool down for 30mins and after that it felt brand new...


and for full honesty...the hot start plunger on mine siezed and the flywheel came apart. thats the ONLY probls Iv had in two years. everybody else has to work on their stuff consitently before race/track days..I change my oil every other track day (or before each race day) and clean my air filter. Thats it.

obviously tires and brakes and chain lube/adjust because they go quickly....

its been a rock for me I love it
 

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the newer models had more holes in the clutch basket in order to flow more oil to the clutch and improve the wet clutch. (I'm pulling it out of my butt right now as to why I drilled more holes.) I really did it because I thought more oil is better to flow through the clutch. I know on ThumperTalk the guys there were doing this and I beat my bike up on track days.

Changed the clutch out and replaced them with stock plates and clutches but added stiffer springs. No issues.

Like you, solid as a rock. I did swap out the hot-start plug with a metal one. I also, rebuilt the water pump-JustInCase. F-it, might as well I thought.

Not one issue on this bike. I'm afraid to ever let it go since it has been so bullet proof.
 

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Not one issue on this bike. I'm afraid to ever let it go since it has been so bullet proof.
ditto...about 3 weks ago I almost traded it for a KTM450sxf with some expensive SM parts (and chassis felt badass) but didnt becuase I like the yam motor better...gonna work on my yami chassis and jam out with my clam out...!
 

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that is the nice thing about SM specific "race" bikes. The suspension is there and imo, that is the most expensive part of the process when converting a dirt bike over.

I was thinking of selling my YZsumo and getting a Husky 450SMR. I'm waiting for the price to fall on the '08 before doing this. Maybe in the fall.

I will not buy a KTM for SM. See them at my tracks with problems when consistently run hard in a season. Too much maintenance, imo. Not a katoom kinda guy either. Italian or Japanese no in between.
 

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Discussion Starter #9
i appreciate it guys thats what i was wonderin basically, i gotta damn good bike, used to be mark burkharts old bike street legal now dude said it dynoed a little over 60, i know its a beast, i gotta put some pilot power races on it slicks aint the best for road. but its alot of fun.
 

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Man, 60 rear wheel hp from a 450 is silly. That is awesome. I almost kill myself with 50rear wheel hp on the track. I can't imagine my 450 with close to 60+ at the wheels.

I love mine.
 

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Discussion Starter #11
yeah its alot of fun i like it better than my old sportbike
 
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