Valve Checks

Just started to do a service on an 03 model for a friend and the clearances on 3 off the valves were just within tolerance.

the LH inlet valve (when sat on bike) had no clearance whatsoever. this suggests to me that the valve could be pocketing in the seat.

just wondering if this is fairly normal on these motors

Yeah, pretty common. Basically it needs a valve job ASAP. New valves, springs, stem seals, retainers, locks and get the valve seats re-cut.

You can shim the one valve back to spec, but after a couple rides the clearance will be gone again.

i would suggest buying an 07 or 08 head for smaller exhaust valves. you would also have less downtime and still have your old head to rebuild for next time you have valve trouble.

for being an 03, a 07/08 head and valve components would be the best bet like fxrs said.. if you were to just rebuild the 03 head - cutting the valve seats, new guides that would put you close to the same price range as new head assembly.. plus the 07/08 has better porting, combustion chamber shape over the 03.. just my 2 cents..

you can reuse the stock exhaust valves and springs, they just don't go bad on these bikes...you can use stock intakes or stainless...new springs of course..i dont knwo why you would want to buy a whole new head...just have the old head exhausts touched up and the intakes re-cut etc

thanks for the advice, i will pass it on

you can reuse the stock exhaust valves and springs, they just don't go bad on these bikes...you can use stock intakes or stainless...new springs of course..i dont knwo why you would want to buy a whole new head...just have the old head exhausts touched up and the intakes re-cut etc

i was commenting if the seats and guides needed to be recut/replaced then the price of which will pretty much be in the same ballpark as a new head which comes complete with new seats/guides.. you just know for sure you are starting off with a clean complete straight head...

if you buy a new head you pay about the same price with less down time you also gain another head to recondition. when we want to

If the head needs guides and valve seat work, plus new valves and springs, you should look into a new head package that has the stainless valves, springs and Ti retainers.

New CRF450 Stainless valve head

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