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Discussion Starter #1
Here is a short video that shows just how small the valve/tappet tolerance is for the Yamaha Star Venture 1854 cc V-Twin engines and just how thin the feeler gauge is and the gauge is at the upper side of the allowable valve/tappet tolerance.

https://youtu.be/rkNDeoiQpyg
 

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COOL and very very well done Sir!! I do find it interesting that Star Yamaha found a way to give such a wide tolerance on the valve adjustment on this new bike. As you stated in the video, "15 thou" (.015) to 0 is a very wide range of adjustment, it seems like the valve train would be really noisy at that gap - WAY COOL they found a way for this not to be so. My childhood was filled with riding the mid 90's small Honda 4 strokes which also had screw type adjusters on the rockers and those were all 3 thou (.003) on the lash and they got really loud if out past 5 thou. It seems like with hydraulic lifters Star Yamaha would have actually run the lash as close to 0 as possible but a wide tolerance like that will certainly come in handy cause, as I remember from helping my Dad adjust those early Honda valves, holding that adjustment screw in place to maintain adjustment while tightening down the locking nut can really be tricky and 3 thou is not much elbow room, 15 thou of tolerance should make the valve adjustment job really easy!!!!!
I enjoyed the video, THANK YOU!!
 

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Discussion Starter #4 (Edited)
COOL and very very well done Sir!! I do find it interesting that Star Yamaha found a way to give such a wide tolerance on the valve adjustment on this new bike. As you stated in the video, "15 thou" (.015) to 0 is a very wide range of adjustment, it seems like the valve train would be really noisy at that gap - WAY COOL they found a way for this not to be so. My childhood was filled with riding the mid 90's small Honda 4 strokes which also had screw type adjusters on the rockers and those were all 3 thou (.003) on the lash and they got really loud if out past 5 thou. It seems like with hydraulic lifters Star Yamaha would have actually run the lash as close to 0 as possible but a wide tolerance like that will certainly come in handy cause, as I remember from helping my Dad adjust those early Honda valves, holding that adjustment screw in place to maintain adjustment while tightening down the locking nut can really be tricky and 3 thou is not much elbow room, 15 thou of tolerance should make the valve adjustment job really easy!!!!!
I enjoyed the video, THANK YOU!!
The correct spec is 0.0015 which is actually ten thousands if you look up the definitions. So that was my mistake.
 

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The correct spec is 0.0015 which is actually ten thousands if you look up the definitions. So that was my mistake.
Things could have changed in the last 25 years but according to my school math teacher, .001 is 1 thousandths of an inch and .0005 is a 1/2 of a thousandths of an inch so .0015 would be 1 and 1/2 thousandths. Ten thousandths in decimal is .010 and, if the factory top tolerance for the valve opening is .0015 then adjusting them to 10 thousandths would be putting you to over 5 times to wide :surprise: - probably not good:eek:.
 

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Discussion Starter #6 (Edited)
Here is the definition on how to read and write in American English 0.0015, the farther to the right you go of the decimal point the smaller the clearance, I did not mean the clearance was ten thousandth as you read it, I was trying to say that the 0.0015 is in ten thousandth see below:



How to write out number 0.0015, (US) American English words converted (spelled out), text written using letters


Convert 0.0015 to (US) American English words:
lowercase:

fifteen ten-thousandth

~ or, simpler ~

zero point zero zero one five



So the clearance spec would be 0.0015 or fifteen ten-thousandth for the feeler gauge.

The maximum clearance spec is 0.0016 or sixteen ten-thousandth.

The farther to the right of the decimal point the more confusing it gets when trying to write it out.

To make it simple the valve lash is considered within spec if it is 0 to 0.0016.

The smallest feeler gauge I can find goes down to 0.0015 so that is just under the maximum tolerance so if you are anywhere between 0 to 0.0016 (sixteen ten-thousandth) you can button up the top end and call it good to go.
 

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Discussion Starter #7
This is a snip on checking the valves.

As a rule, if you can’t get a .001” or .0015” between any rocker arm finger and its valve stem, you can call it “zero” and stop there. When in doubt (or if you’re feeling particularly critical),
whichever valve in a valve-pair shows clearance, loosen the lock-nut on the adjustable finger and back out the adjuster screw until it clears the valve stem. Then screw it back in with finger-tip effort until it contacts the valve stem again and then retighten the lock-nut. By doing that, as long as the adjuster doesn’t turn while tightening the lock-nut, you’re setting both valves on that rocker arm to zero-lash. Now turn the engine to TDC-compression stroke on the other cylinder and repeat the valve check/adjustment process.
 
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