2007 - 450 Newbie Valve Question. Shim or Replace?


3 replies to this topic
  • thefickler

Posted May 06, 2013 - 06:59 AM

#1

Hey Guys,

I had a quick question about valves, and wondered if someone would be able to help me make a few decisions based on some valve spec. measurements.

I bought this '07 450f in the spring of last year. It needed some normal things replaced, and I really cleaned things up on it and the bike ran awesome last year. I checked the valves when I bought it, and they all were within spec. I did mostly trail riding last year, and the MX track once. I’d say probably 60 hours of riding all summer with the limited time I had.

Anyways, fast forward to this spring. I have gone to the track twice so far, and last week I wanted to check my valves to just make sure they’re ok. Well they are not ok. They have moved, and one has moved quite a bit. Basically I have one in need of help, and 2 that are right on the borderline of being out of spec. My question is, can and should I shim all of these? Or just do a whole new top end? I’m not sure how much of a gap you can shim for and be ok with.

I also added a picture showing my measurements from 2012, and 2013. Thanks for any insight guys,

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  • Valve Measurements.JPG


  • thefickler

Posted May 07, 2013 - 05:53 AM

#2

So I have some new information behind my issue, and it seems pretty interesting. I took the buckets and cams out yesterday to see what shims where in the bike, and none of them have any numbers on them. Does this mean that someone else has already shimmed this bike at some point?

Also I have added a couple pictures of my problem valve. The other valves are all the same color, in terms of oil etc that is inside the bucket and on top of the valve keepers and stem. But my problem valve (valve on the left side of the pics) seems to be black, almost like a sprak plug when its fouled, real sooty looking. I thought maybe I was leaking at the valve and blowing combustion up into that bucket through the guide, but my intake is spotless, so that doesn't make sense. I also seen that when looking at that valve face through the intake (where the carb would be) the problem valve face has a bunch of crap on it, while the other 2 intake faces look very clean from what I can see. I'm thinking I just need to pull the head and go from there.

So has anyone ever seen this?

Attached Thumbnails

  • P5060308.JPG
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  • NitrousR1

Posted May 11, 2013 - 06:22 AM

#3

You probably have a leaking valve seal on that valve. Do you notice any smoking when you first fire the bike up- a poof of white smoke on the first fire up- thats classic valve seal leakage.

As far as the clearances go, you can adjust them 1 time, next time the valves are out of spec-replace them and have the seats machined. These are titanium valves with a wear coating on them. once that coating wears off they will move pretty quick and you will be adjusting valves very often.
It sounds like this bike has some hours on these valves- not a bad idea to replace them and have seats cut. If you want to save some money you could adjust them into spec, this will be your first and only adjustment. if they go out of spec again-replace.

As far as the shims go, they were marked with their size when new, but that number can wear off over time. Measure each shim with a micrometer or caliper. Refer to your chart for the correct size and buy the Hotcams 9.48mm valve shim kit. Money well spent and you will need them later on.

  • thefickler

Posted May 13, 2013 - 09:48 AM

#4

Hey R1,

I dont have the puff of white smoke. I thought maybe it could be a valve seal as well, due to the one valve retainer and bucket having discolored oil on it. I had never seen that before when checking my valves, but Idon't see how the valve seal would change the clearance values. I do know that I do not have a leaking valve seal however. I ended up soaking the intake ports with some seafoam and carb. cleaner to try and get some of the deposits off of the valves. While I had the intake ports soaking, the volume of cleaner in the port never changed, or seeped past the valve seat. I also would expect the intake port in the head to be blackened by combustion coming back up and into the head on a leaky intake valve. My intake was as clean as could be. I had an old '72 Honda that had leaking intake valves, and it was pretty evident once u looked inside the intake ports.

I ended up cleaning the valves best as I could by soaking them and using air to blow the crap off. I then hit all the valves a few times to see if I could break free any carbon that may have been holding the valve open. I'm going to put my cams back on tonight, roll it over a few times by hand, and then re-check my clearances. If they have changed, then I will have a much better idea on what direction I'm going to take to fix the issue.

Thanks for the insight on the hotcams kit, I'll be picking one up.





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