03 CRF450 Maintenance

[AndrewPA]

Hey all, I'm back on ATM after a few months hiatus, been having a blast with the new arrival to the family . 2025 Supercross (Lites ) Champ btw!

Anyway, I have an 03 CRF 450 and am wondering what engine maintenance I should be looking at. It does not have a huge amount of hours on it. I rode probably 10 times the first year, 15 times last year and 3 times this year. Of course, I realize riding style and abilty impacts wear and tear but essentially its not been thrashed.

I know I should be checking the valve clearances but what about valve and spring replacement themselves? Is it worth looking at new valves and springs ? If so what brand/type does anyone recommend? Also, do new valves require any sort of 'lapping'? I understand one does not grind/lap valves in the traditional sense, at least I believe you don't, but does anything need to be done in that regard assuming I go for new valves/springs? Any other things I need to be looking at and checking?

Thanks!

[VET393]

Follow the manual and keep the air filter clean and change the oil regular.
In my bike I replaced with Kibblewhite stainless valves. The bike always ran great and started good.

[AndrewPA]

Thanks Vet. I'm good with the 'regular' maintenance, oil/filter and all that but was after the specifics on the valves. Kibble huh? Thanks, I will check into that then.

[Woody_393]

I personally wouldn't worry about the valves until they go to Zero clearance.

Then go with RHC valves

BTW, you really should check your valves, it's easy and will let you know where they are at.

[VET393]

Thats what I did, only I had Eric Gorr do mine.

[Faded]

Check the valve clearance; this is going to be the two stroke equivalent off adding premix oil to the gas. With running the stock parts checking valve clearance after every 10 hours of run time would be a good conservative estimate offering a “safe bet” type of protection. The stock intake valves are two piece units made of Titanium that are welded where the valve stem meets the valve head. Titanium has a tendency to become elastic and stretch before it breaks so when you see your valve clearance require a shim size 3 sizes smaller (or more) to get valve clearance back in spec it’s time to seriously start looking into getting your head checked. Otherwise the alternative could possibly be broken intake valves and the excessive damage that comes with it.

If you’re planning on aftermarket valves/springs there are two names that really stand out for quality and durability; Kibblewhite and Ferrara. The Kibblewhite stuff can be had through Eric Gorr’s Forward Motion while the Ferrara bits can be obtained through Ron Hamp Cycle.

Another cost effective alternative is to run the stock Honda TRX steel intake valves with new stock springs although this doesn’t get you very far compared to the aftermarket alternatives.

The springs are the weak link in the stock set-up but once addressed, and combined with quality stainless steel valves, valve train life expectancy is increased almost ten-fold over that of the stock parts (estimated 300hrs).

With the steel and stainless steel valves you can lap them to the head, but results will vary and may have detrimental side effects. A good head job done by the above tuners will include a 3 angle valve job cut with a precision valve seat cutting tool called a Serdi. With a competent operator this insures a precision match between the valve and seat for optimal sealing of the combustion chamber. Lapping with Ti valves, stock or aftermarket, is a no-no.

If you can wait I have a DIY tool in the works that will help four stroke owners shed some real light on the condition of their engine…

[Satch0922]

Listen to WoodyC and Faded.....the are right on the money.

[AndrewPA]

Thanks for all the good advice everyone, lots to go on.

Appreciate it.