Valve adjustment help... Again.... I don't think I can math right.

As u/elkster88 said in the other thread, part of learning how to use a feeler gauge is developing a feel for tight, loose and nominal. That feel when using the go/no go method can throw off the end result if you get it wrong.

It would also help to know what you are using for measuring equipment.

  • What are the graduations on the feeler gauges you're using?
  • What are you using to confirm the size of the shims in place and being inserted? If you are using a caliper I'm going to say it's not accurate enough. Use a micrometer. Even a digital caliper likely only has a read out that reads to X.XX mm and the accuracy of that last decimal place is greatly influenced by your feel and use of it. A micrometer will have a higher resolution helping to minimize the tolerance of the measuring equipment and user influence.

Your math is right but you likely have a error in your feel and maybe measuring equipment and a tolerance stack adding up in your measurements. Also never trust the number printed on shims. It's not often the marking is wrong but it happens and once you get into bikes that have had multiple adjustments, some times by many people you may run into shims that have been dressed(ground, sanded) down to a thinner size to achieve the desired goal.

When you are making your initial measurements you need to also need to be mindful of the oil film on the valve train components. That oil film can add to your tolerance stack by changing the feel or gap. For instance on valve operated by rocker arms a seemingly tight valve can "loosen" up by pushing on the cam follower side of the rocker arm thereby squeezing out the oil between them. There is also a oil film on the buckets and shims that can slightly alter your measurements if you put the shim/bucket back in totally dry. If the cam is being pulled to access the shims, putting it back dry is a no no and you have to make sure it's properly torqued and seated before your remeasure.

/r/motorcycles Thread