CRF 450 valve info. needed

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#1
After a lengthy read through the CRF valve issues here on DRN, I'm wanting to know if putting stiffer intake valve springs in, (such as Kibblewhites or R/D) would lengthen my service intervals for shimming intake valves?

Also, would having Ron Hamp or Kibblewhites softer seats be a wise investment as well?

I'm reading that stiffer intake springs, softer seats, and stainless steel valves (in addition to proper airbox/airfilter maintenance, oil changes, etc) are some combinations I can consider.

I have a brand new 04 CRF that hasn't been started and wanted to stay clear of the valve issues that my 03 had.

Any insight from you guys would greatly be appreciated as I'm learning about this 4 stroke world every from every thread I read.
 

Rich Rohrich

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#3
A couple of quick questions :

What type of riding and rpm will the engine see ?

What type of hours will the engine see per week?
 
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#4
Rich, I'm ashamed I didn't include that info.!

I race A class MX only in Indiana. The bike sees the upper end of the rpm range only, but I would say I don't overrev or downshift in mid-air. Not wanting to neglet top end maintenance and checks, but just make it longer prior to getting new parts.
 

Rich Rohrich

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#6
Sorry I didn't get back to this sooner, I sort of lost track of the thread over the holidays. :eek:

Kibblewhite has two different spring kits for the CRF now. For engines that have not been heavily modified then the current KPMI Kit #30-30190 which includes retainers, springs, keepers and collars works really well with the KPMI stainless steel valves. On a bike that is more heavily modified engine and being raced on a regular basis by a rider who is consistently running the bike in the upper RPM range Mike Perry from KPMI suggests using Kit# 30-30470 which also includes retainers, springs, keepers and collars.

Eric and I have installed a number of the 30-30190 kits with the KPMI stainless steel intake valves but don't have enough data on running these springs with the lighter OEM titanium valves to know for sure if it will have a positive affect on reliability.

I'll be e-mailing Mike Perry over the weekend so I'll see if he can shed any light on this, or maybe even drop in to add his comments to the thread. I'll get you an update by Monday.