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Lifter bucket dented

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I found an old thread when searching, but my problem is a bit different.

 

IMAG0594.jpg

 

Picture in post shows right lifter bucket with circular dent.

 

What can cause a circular dent in the top of a lifter bucket on a 2006 CRF250x? I previously shimmed valves at about 33 hours and everything looked fine. The bike was getting hard to start at 58 hours, so I checked valves and found the dented lifter bucket, and slight flat spot on cam lobe (sorry no pic of cam). The valve clearance was tight, under .004". I went ahead and shimmed the valves to proper clearance and the bike is running great.

 

2006 CRF250X

Athena 280 Cylinder

Athena Top End kit (60 hours)

Hot Cams Stage 2

Pro X SS Valves/guides/springs (60 Hours)

Hot Cams Bottom End (120 hours)

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hard to say, is the bore the bucket rides in damaged at all? If the bore is clean, it's possible the cam lobe had some imperfections to create this. the buckets do rotate in the bore, cam lobe has a slight angle to it to promote turning of the bucket. I can't see the pic well enough to see how deep the dent is, can you measure it? was a shim left out?

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The dent is almost the shim thickness. The shim was in place when I removed the bucket. I picked up another bucket today and plan to install it with proper shim tomorrow. I'll check the bore then. The rotation makes sense. An imperfection on the edge of the cam lobe could hammer out the circle.
My local race shop gave me a bucket and offered me a used stage 2 cam for about half cost of new one. I'm gonna run the new bucket for a few hours with flat spot cam and see what happens. Probably end up adding the used cam if I see same problem later on. I sure don't want to get a brand new cam and add a flat spot it.

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It sounds like its time for a valve job. You didnt say what size shim you put in it or what size was in it before you last shimmed it.

A lot of times when a bucket gets wiped out its because the cam lobe stays in contact with the bucket and there is no longer any clearance. 

Why are you going to run a different bucket using the same cam with a "flat spot" in it?

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@TDW
Because I'm cheap, would be the short answer.

I'm not sure what the shim was when I installed it, but it was .061 when it came out. I'll measure the dent in the cam bucket and report back. It may not be as deep as it looks. Keeping a record of shims in the future is a good idea though. I'll measure the shims when I remove my cam and put the record inside the shim kit box.

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For the center of the shim to collapse inward like that often is an indicator that there was no shim or support between the center of the bucket and the tip of the valve stem. So if there is a worn retainer or cotter issue, and like what was already mentioned the clearance went away the cam just stays in contact in the bucket surface and damage occurs. Thats why doing a valve job now may save you money and cause less damage overall.

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Is there a way of knowing if there is an issue with the valve without removing the head? I've never removed the head before and not sure what the process is. I had the Pro-X SS valve kit installed 60 hours ago. There shouldn't be a problem, but things can happen.

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2 hours ago, SquareAce said:

Is there a way of knowing if there is an issue with the valve without removing the head? I've never removed the head before and not sure what the process is. I had the Pro-X SS valve kit installed 60 hours ago. There shouldn't be a problem, but things can happen.

Here is a good link for checking and adjusting the valves,

If you have a owners manual it has good info about removing and installing the cylinder head. Otherwise with the head installed you are probably limited to visually inspecting the retainers and might be able to see something wrong after removing both buckets and doing some comparing from side to side. You would be able to see the tip of the valve stems and if all the cotters are in place at least.

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The cotters are in place and I can see the tip of the valve stem, but don't see anything different from left valve. I decided to change out the dented bucket for a good used one I got for free. The cam lobe doesn't look that bad, so I reinstalled it. The dented bucket and new bucket measured the same from bottom edge to center on inside. The dent on the bucket measures .006" from top.

I somehow got the bike out of time putting it back together and will have to take it all back apart tomorrow. I'm a bout one more mistake or mishap away from the funny farm.

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Well good luck and be sure to get the clearances in spec!

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Is there a way of knowing if there is an issue with the valve without removing the head?


Yes. A leakdown test can provide useful info. I'm not positive, but I think some auto parts stores may loan them. Plenty of good You tube videos depict the procedure.

Good luck!
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I can't get proper clearance with the new bucket. I put the dented bucket back on and it runs great. I plan to do a complete top end and valves in the near future, but gonna run like is for now.

I was able to get the bike timed properly after a bit of trial and error. The stage 2 hot cam has incorrect timing marks that do not line up with the top of the head. I already new this and always mark the timing chain and cam sprocket with a sharpie. This time the chain slipped on the bottom sprocket and the marks I made were clearly in the wrong location.

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I would highly recommend NOT running that bucket or damaged cam. If the cam is losing material, it's making its way through every part of the lubrication system, bearings, etc. and you're going to have a lot more headaches in the near future. 

 

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@redhurricane
That's good advice. I rebuilt bottom end 120 hours ago and that's a huge expense. The cam seems to be dented into a flat spot. The deformation is very slight, but apparently enough to dent the bucket.

I will follow your advice and throw in a used one before hitting the woods again. Seventy bucks will sure be better than the alternative. National Enduro comes to town in November and I plan to have the bike in tip top shape by then.

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