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Discussion Starter #1
I was wondering what the shims look like. Since it seems from what I have read here that the adjustment is always necessary to increase the clearance then would it be possible to remove material from the shims themselves to make same adjustment? This would allow the adjustment to be precisely made to the maximum clearance, thus providing more consistency between the valves.

Material could be removed from the side of the shim that sits on the valve head, not the side that is subject to wear from the tip of the rocker arm.

Before you go off on a litany of criticism, know that this is a method that has been used for decades, dating back to long before WW2, where the actual end of the valve stem was ground to get the proper tolerance.

The thinking behind this question is due to the fact that valve clearances seem to close with wear and 2-4 thousandths of clearance could fairly easily be achieved with careful (very careful) removal of material from the valve head side of the shim. Also would allow clearance to be precisely set at maximum while shim choices would always be somewhat of a compromise.

regards
Badger
 

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The shims look like button cells (the -ve side on both sides).

If you wanted to remove material, it would be possible - but by grinding (using a surface grinder, after preparing a mild steel holder to seat the shims in it) the same, as the material is extremely hard.

I prepared fresh shims out of 100 x 7.5mm die pins using this technique as the dealership (or to be more accurate, Honda India) had NO idea as to when they would be available. BTW, the OD of the shims is 7.45mm.
 

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Discussion Starter #3
Thanks arn. I was actually thinking of using a fine oil stone, so heat would not be an issue. Time would not be an issue for me as my priority would be to get the clearance to the maximum acceptable on every valve, exactly the same.

It has been my experience that in many cases once everything has settled in and the wear pattern is developed an adjustment would last a considerable time.

I adjusted the valves in my 1973 Alfa Romeo GTV, which required the removal of both cams after measurement of clearance, then replacement of the shims between the buckets (which directly contacted the cam) and the valve stem. 100,000 miles later the tolerances had closed exactly .001 inch on every valve. They had not been done until 59,000 miles when I first did the adjustment.

regards
Badger
 

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That might work pretty well. The only question would be how deep the hardening goes through the surface and even how critical it is to have a hardened surface facing the valve which probably has very little relative movement. You may also find that you can trade a couple of the shims locations to make the adjustment so as to only have to polish a couple.
 

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I think the material would have to be properly hardened through and through, as any softness would allow the shim to deform laterally and ultimately get jammed in the seat itself, apart from changing dimension vertically as well.

Labour being cheap here, the shims cost only about $1.5 to make (the die pin cost $2), and they've performed without any problems for about 8000km now. I believe Honda prices them here at about $5.

Given a choice I'd rather pick them up at the dealership, does not seem worth the time to do the running around :p

@sendler: The shims I had on the bike had quite a significant size variation between them.
 

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Discussion Starter #6
The dealer here is a 25 mile round trip. As difficult as the valve adjustment seems to be, I am not sure I could trust them to do it properly. I ride my bike very conservatively and the wear should be relatively minor, but I want to be in a position where when I start the process I know I can finish it without waiting for parts, only to find I have to choose between too much and too little as far as clearance. Also to a level of precision that a commission tech probably would not approach.

The job does not scare me in the least especially after reading Sendler's excellent post, but my hands are 61 years old and I can't snatch flies out of the air the way I used to. I think I will wait until 5k, after changing the oil to Amsoil synthetic (motorcycle specific) oil at 3k which is coming up soon. Might do it earlier if I do not get to 5k before next summer. Rode it today at just above freezing and my gear worked fine, so it will probably be a few months before I hit 5k.

At 2700 miles I can really feel the bike starting to shift and run nicely, and I want both of you, arn and Sendler to know I appreciate your time and excellent advice. On the depth of the hardening on the shims. I am almost certain it is at least .010-015 inch and possibly deeper, since the material removed should never exceed .005 inch then I really don't see that as a problem. Even if the head of the valve did work some wear against the bottom of the shim, that would actually increase the clearance, which would offset the normal wear induced reduction in clearance. Since the shim is in constant contact with the valve head then there would be no "hammering" between the parts and with no relative movement (shim to valve head) there should be not any real issues there.

regards
Badger
 
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