2005 YZ450 valve replacement


4 replies to this topic
  • ringstad

Posted February 09, 2012 - 08:12 AM

#1

A good friend of mine asked me to help him do a top end on a bike he just bought. He bought some new kibblewhite valves from an ebay store. We brought the head to a local machine shop and they touched the valve seats and matched the valves to their holes. We did the actual head assembly ourselves and I found that the outside valve clearances were off the charts. Ive been scratching my head and considered having the outside seats recut to make up the difference. At this point it appears we may have got two center valves and one outside valve and the machine shop didnt know any better and set it up with the longer valve in the center. I need to know whether the center valve is suppose to be longer than the outside valves because thats the setup we have now. These are kibblewhite white diamond valves and I have one valve that is 3.040" and two that are 3.000". Thanks in advance!!

  • grayracer513

Posted February 09, 2012 - 09:09 AM

#2

Or, maybe three center intakes? If it were one outer and two centers, I don't see how he could have set up the clearance on the center valve. If you have the original valves, compare the lengths. The center should be the shorter one. But 3mm? Something's not right.

I assume you are aware that stainless valves require heavier springs to match their weight (about 160-170% of the weight of the OEM Ti valves).

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  • ringstad

Posted February 09, 2012 - 10:19 AM

#3

Or, maybe three center intakes? If it were one outer and two centers, I don't see how he could have set up the clearance on the center valve. If you have the original valves, compare the lengths. The center should be the shorter one. But 3mm? Something's not right.

I assume you are aware that stainless valves require heavier springs to match their weight (about 160-170% of the weight of the OEM Ti valves).


Thanks for the reply!! First the machine shop didnt assemble the head to check clearance, we did that. They just said they matched up the valves to their holes. Unfortunately someone else tried replacing just one valve before I got involved and I think they got the wrong size then too. I measured the old ones and its confusing because theres three different sizes 3.004", 3.018", and 3.040". I have yet to see the original valve that was replaced to measure it but....

Not sure what you mean by the 3mm? But I've measured the new valves too and at this point the longer one is in the middle. So it sounds like I need another longer valve and swap them around with a 3.000" valve in the center.

As far as the springs go he did want to use the original oem springs to save some money but I was able to convince him he needed to get the spring kit too. So he got the matching springs, retainers, base washers, and seals. So I think we're ready to go if we could just get the other stuff figured out. Thanks again

  • grayracer513

Posted February 09, 2012 - 10:35 AM

#4

I misread 3.00 as the clearance you had.

KW makes intakes in 4 lengths. 3.040, 3.030, 3.00, and 2.990". I don't have the OEM OAL measurements handy, unfortuantely, but I thought there was more than .040 difference in the center and outers.

  • ringstad

Posted February 09, 2012 - 10:41 AM

#5

"3mm" was the clearance you had. Way out of range when the biggest shim you normally see in one is less than 2.0mm (#200). I assume you had some sort of shim in place when that measurement was taken.


My bad... I'm not explaining myself very good. The measurements I'm giving are the enitre valve length in inches.

The measured valve clearance are R: .033" and L: .030" and with the installed shims they dont make a shim big enough. Sorry I have to convert everything to inches because thats what I use in the shop.





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