check list

[motogandy3]

what all do i have to buy if i am getting ready to rebuild my 03 450... i just have a wierd feeling that its about to go out so i need to start saving... i just want what the norm. is....

thanx,

john

[PK]

It depends on how many hours you have. If it's a bucket load of hours, I would go full tilt.

New crank & bearings/seals (you can measure the play on the crank so yours may not need it if it's still in limits)

piston & rings

timing chain

intake valves & seats(the exhaust valves are stainless steel, shouldn't worry about those)

I can't think of much else. Anyone else?

[TapptOut]

plus all the stuff that is normal to change if you havent done that already

Chains, Sprokets, etc.

[grayracer513]

intake valves & seats(the exhaust valves are stainless steel, shouldn't worry about those)

All 5 valves are Titanium in the YZF's starting withe 2001. Prior to that, they were stainless steel.

The seats will not need to be replaced, although they should be re-ground (not cut, at least not the finishing pass), and normally don't need more than a very light touch up.

The guides should be checked, but are probably OK.

The list for the head should include all 5 valves, all 5 springs, and valve guide seals. Machine work as necessary.

New rings, new piston (unless it's absolutely perfect, and it might be), and check the cylinder for wear. Refinish or replace the cylinder as needed.

Check the crank carefully. The '03's had a very occasional problem with rod bearings, so be critical. Check the wear on the crank sprocket. If you're going to open the cases, replace the main bearings, and check all the trans bearings and replace any that are suspicious.

Inspect the oil pump; both halves.

Replace every seal that you can. Otherwise, just check over the whole thing for signs of wear

[PK]

Grey is right. I'm use to working on my wife's old POS CRF250. The exhaust valves on that thing were stainless. I guess if the YZ broke more often I would have remembered that. ?

[grayracer513]

I guess if the YZ broke more often I would have remembered that.

? Yeah, too bad, huh?

[Ga426owner]

The 03 is pretty bullet proof...depending on # of hrs...tear it all down and check the valves and valve seats for wear. See above notes for servicing.

You can plan on replacing piston, rings, cam chain and cam chain tensioner at the least to freshen it up....

When I did my 03 recently it had surprisingly little valve train wear....at over 125hrs....yamaha dependability!

I added a 470 kit and full hinson with Top end and it feels like new...only with more grunt ?