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Old 09-24-2011, 10:01 PM   #16
bumbee800
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Quote:
Originally Posted by itsatdm View Post
These are not a shim on bucket or shim under bucket valve system. This is a conical "shim cap" that fits on top of the valve stem. The cam lobe connects to a following lever connected to the valve stem
Typically any wear tightens the valve clearance. I do not know how much wear occurs to the "cap" an I doubt they are measured and saved. They are cheap and would not bother with discards. I thought it important enough to have the dealer to do them to ensure warranty problems, though ther has been very little wear reported.
One end of the follower pivots on a shaft and the other end of the follower rest on top the valve stem. The cam lobe pushes down on the follower at some point in between the pivot and the valve stem. There fore you have 3 contact points. The pivot point that should never move, the cam lobe to follower and then the follower to the adjuster cap sitting on top the valve stem. The pivot point just rotates on a bearing and has very slow wear rate so take that out of the mix, The cam lobe to follower is metal to metal contact so it will wear only increasing valve clearance. The valve adjusting cap contacting the follower is metal to metal contact so it will wear only increasing valve clearance. The only way valve clearance can decrease is if something increases in length or grows in diameter and there is no way anything in this entire valve train increases in diameter or length they only decrease. There fore the valve clearance can only increase not decrease. The only possible way the valve clearance can increase is if the valve is pushed up further into the valve seat causing the valve stem to push up further into the valve train. Again if this is happening no adjustment in valve clearance will remedy that problem, the only fix is to put in harder valve seats.

bumbee800 screwed with this post 09-24-2011 at 11:12 PM
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Old 09-25-2011, 03:43 AM   #17
Snowy
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Bucket and shim???

facepalm

I swore I'd never buy another bike with bucket and shim adjustment again......


Time to trade.




Conical cap/bucket and shim......it aint locknut and screw. Therefore, it's a dickaround.
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Old 09-25-2011, 05:30 AM   #18
itsatdm
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Quote:
Originally Posted by bumbee800 View Post
One end of the follower pivots on a shaft and the other end of the follower rest on top the valve stem. The cam lobe pushes down on the follower at some point in between the pivot and the valve stem. There fore you have 3 contact points. The pivot point that should never move, the cam lobe to follower and then the follower to the adjuster cap sitting on top the valve stem. The pivot point just rotates on a bearing and has very slow wear rate so take that out of the mix, The cam lobe to follower is metal to metal contact so it will wear only increasing valve clearance. The valve adjusting cap contacting the follower is metal to metal contact so it will wear only increasing valve clearance. The only way valve clearance can decrease is if something increases in length or grows in diameter and there is no way anything in this entire valve train increases in diameter or length they only decrease. There fore the valve clearance can only increase not decrease. The only possible way the valve clearance can increase is if the valve is pushed up further into the valve seat causing the valve stem to push up further into the valve train. Again if this is happening no adjustment in valve clearance will remedy that problem, the only fix is to put in harder valve seats.

I have been doing my own valve checks for the last 14 years on two bikes with bucket and shim. 14 valves, 90,000 miles with numerous shim replacements and my experience has been different. Just did the first one on a KLX that had a recent upper end job, including the seats. Same story.

The 800 is not your typical bucket and shim design. Perhaps it should be called lever and cap. The warranty is up, so I will be doing my first on the bike and maybe your theory will be correct.
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Old 09-25-2011, 05:41 AM   #19
MikeMike
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Quote:
Originally Posted by bumbee800 View Post
There fore the valve clearance can only increase not decrease. The only possible way the valve clearance can increase is if the valve is pushed up further into the valve seat causing the valve stem to push up further into the valve train. Again if this is happening no adjustment in valve clearance will remedy that problem, the only fix is to put in harder valve seats.
You lost me there. Do you mean to say "The only possible way the valve clearance can DECREASE (instead of "increase") in the second sentence above?
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Old 09-25-2011, 11:57 AM   #20
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I am a rock when it comes to understanding how these things work, but at 88,000 miles two valves were too loose out of spec and were re-shimmed to bring them back in. This was the first time an adjustment had been made in the life of this machine which had been dealer maintained up to 36,000 miles. After 36k I figured it was good to go for a substantial amount of time, and I was correct. So as opposed to my R bikes, this F appears to get loose instead of tight. Is that normal? No idea. But just to comment on the OP's question, I wouldn't obsess over the valves with only 20k.
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Old 09-25-2011, 03:12 PM   #21
itsatdm
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Could be that they were not set to spec in the first place. Better to loose than to tight.

All parts wear. Cam lobe or wear on the follower would result in increase clearances.

The valves live in a pretty harsh environment. High temps, high RPM plus containing basically an explosion causes them to wear also. The valve seat is usually forced into the engine block over time, all would decrease clearances.

So it could go either way, but typically they decrease and fall within the range of normal, unless it happens in a short period of time or the engine loses compression.

I do not know if there is some peculiarity to this design, but in principal it appears very similar to my TDM 850 with its shim on the valve stem and the bucket being placed over it for the cam to ride on. The clearances always got smaller. Sounds like it wears like that design, as there was very little movement of clearances.
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itsatdm screwed with this post 09-25-2011 at 03:17 PM
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Old 09-28-2011, 11:32 PM   #22
bumbee800
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Originally Posted by MikeMike View Post
You lost me there. Do you mean to say "The only possible way the valve clearance can DECREASE (instead of "increase") in the second sentence above?
correct my bad. The only way the valve clearance can DECREASE is if the valve is pushed up further into valve train;

One mistake many people make when checking their valve clearance is checking the valve clearance when the engine is not completely cold. You should only check valve clearance after the engine has been sitting over night. You will see a decrease in valve clearance if you check your clearance when the engine is warm due to expansion. The other way you can get a false reading is checking the valve clearance slightly off of TDC which can also give you incorrect valve clearance.

I stand behind my own experience and common sense that the valve clearance will always increase with mileage due to wear between the cam lobes and cam followers.
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Old 09-29-2011, 07:18 AM   #23
uraberg
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I apologize, I was talking about shim under bucket type valve trains. I guess I need to look better at which subsection of the forum I post in...

In my experience, the clearances (of shim under bucket type systems) always decrease over time, mostly because of mild tuliping of the valve. The change this causes just seems to overshadow any wear on the valve stem, or the cam lobes.

In any case, my response was not appropriate for the thread.
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Old 10-28-2012, 10:36 AM   #24
JRWooden
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Quote:
Originally Posted by itsatdm View Post
I have been doing my own valve checks for the last 14 years on two bikes with bucket and shim. 14 valves, 90,000 miles with numerous shim replacements and my experience has been different. Just did the first one on a KLX that had a recent upper end job, including the seats. Same story.

The 800 is not your typical bucket and shim design. Perhaps it should be called lever and cap. The warranty is up, so I will be doing my first on the bike and maybe your theory will be correct.
Old thread I know, but ... I'm curious ...
What did you find in terms of lash increasing or decreasing on the 800?
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Old 10-28-2012, 10:17 PM   #25
Indy Unlimited
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39,500 miles and one of my exhaust valves is just slightly tighter than spec.
First time I have had to make an adjustment in all those miles. Very happy.
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Indy Unlimited screwed with this post 10-28-2012 at 10:23 PM
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