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This post is asking what people think about the need to loosen the cam chain or leave it alone during valve clearance checks. I know this subject has been discussed but I was thinking of looking at it a bit differently that I am not sure anyone has talked about. Yes, some people say you need the tool to take the tension off the cam chain and others say you don't.

I say you don't and I have my thoughts to as why which others have not said why. I've done a lot of valve checks and never had to take tension off anything. If the Honda GL 1800s are within complete specifications as to torque values holding the cam shafts in place, then they can not move side to side or up and down or any other direction. This should also stay true if the journals are not worn causing slack in the cams as they sit and are torqued down. That being said, I don't see how a slack cam chain or a well adjusted cam chain would have any affect on the cam lobes spinning on top of the valve buckets. A cam chain that is not slack is not going to allow the lobe to ride higher nor if the cam chain is correct, it is not going to pull the cam shaft closer to the valve buckets for a tighter fit. That is just my opinion and that is why I don't believe in the extra effort to use a special tool to check valve clearance.

Any comments are appreciated with the exception of statements like: "The manual says..."
 

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Just say'n...I tried it BOTH ways. My results...it does, in fact, make a difference. Not smart enough to know all the Physics behind it all though.
 

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It makes about a 1/2 shim increment size, or about 1/2 a thousandth inch difference on some valves, some not. You have a 3 thouandth inch or 3 shim sizes where the valves are whithin spec, so chances are the minimal difference is not something to be overly concerned with, but for sure you need the tool to be able to change shims if you do find any out of spec.
 

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Others have tested it both ways. I recall most agree it makes little difference - not enough to warrant de-tensioning unless you suspect cam shaft bearing journals are worn which would allow the timing chain tension to move the cam enough create false readings - especially at the forward end of the engine closest to the drive sprockets.
 

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I posted about this recently and on my 06 with 45k on it there was little to no change with or without tension. I checked every valve both ways. I'm sure there is some reason Honda wants the tension off but my thinking is that the engine runs with the chain under tension so that running clearance is what counts
 

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I had mine checked at a dealer who services a lot of Goldwings.
I'm pretty sure they did not take tension off the cam chains.
All valves were still in spec at 54,000 miles.

Sent from my SM-G960U using Tapatalk
 

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Discussion Starter #7
I posted about this recently and on my 06 with 45k on it there was little to no change with or without tension. I checked every valve both ways. I'm sure there is some reason Honda wants the tension off but my thinking is that the engine runs with the chain under tension so that running clearance is what counts
I agree with you. Of all the replies, not one says why the tension should be released. One says a half of a thousands. Hmmm, that means .0005 and the valves can be off plus or minus .001 from intake of .006 or exhaust from .009. So if you measure .006 and think its off by .0005 then you are still within specs.
 

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Any comments are appreciated with the exception of statements like: "The manual says..."
Do you have a valve lash spec for cams under tension. If so you should be good ... do it that way !!!
 

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The reason it makes a difference is the oil clearnce of the machining specs. The tension, when there is no oil pressure pulls the front of the cam shaft inward on the oil in that clearane; chiefly on the front one or two valves. I have yet to check my 2018, but on the 2002 I checked both ways. There was a tiny difference, less than half of the increment of even the half step sized shims. If you are a "center spec fanatic", then it may make a little difference. If you are an "in spec is in spec and good enough type of person" it probably does not. I don't mind my clearance being a bit on the loose side of "within specification range"; but I reshim if "in spec" but on the tighter end of the range. Tight clearances shorten the dwell time of the valve faces upon the head seats where the heat transfer to the coolant occurs. The tool is handy to have, especially on right bank, if you have to remove the cam shaft for shim swaps.

prs
 
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