邮件翻译

Mark and Leigh,

We have recently had intermittent issues with exhaust valve guide wear on our 80cc synchronous generator engine. The videos mentioned below simply show someone wiggling the valve on worn engines like a loose tooth by grabbing the valve face with the valve extended out from the seat about an inch just to confirm the discussion. We have been building this otherwise robust engine for several years, so customer service feels that something has changed. The problem is not occurring on every engine, so I assume various customer duty cycles, maintenance, materials variations and so on could be contributing. I have found samples of new assemblies with max design clearance (.003 inch) but none that are beyond tolerance. I gave Joyce a sample worn head which she carried for discussion in China.

针对80cc发动机气门导管的磨损问题，我们已经陆续讨论过几次。附件中的视频，表明了气门导管存在磨损的现象。这款机器我们已经生产了好几年，现在出现问题，售后服务人员以为有什么东西发生了变化。但并不是每一台发动机上都存在这个问题，所以我考虑了诸多可能引起问题的原因，如顾客的使用周期，维修，材料的变化等等。我看了新装的最大间隙为（0.003英寸）的样品，但是这些样品都在公差允许范围内。我将一个磨损的汽缸盖交给了Joyce，送回中国讨论。

Please note the messages below and let us or YF know if you have any immediate suggestions or comments. They may be on the right track by changing the supplier and material spec, but I don’t know any of the details. Leigh, you may be able to learn more on your trip.

如果你们有什么建议，请告知我或者耀锋。耀锋通过更换供应商或者材料来解决这个问题也许是正确的，但我并不知晓其中的细节。Leigh，你也许可以通过你的访问了解更多的细节。

Another fact to keep in mind. Mitsubishi builds a similar engine but has a passage that helps take oil from the breather on the intake side of the head and distributes it to the exhaust side on top of the valve guide. The passage is formed by a groove in the aluminum head and bordered by an extension of the head gasket and a stamped metal shield. The metal shield is like an extension of the washer under the intake

valve spring. About 3 years ago we had to eliminate this feature due to a patent issue (attached). The factory did a limited number of 500 hour durability tests and concluded we should be ok. This field experience might be telling us something different or else something else has changed. Regardless, we know going in that we may be suffering some reduced lubrication that must have also affected Mitsubishi. I’m wondering if we can accomplish the same thing by running a small diameter tube from down in the intake side breather and route it over to the exhaust side, or do some other distribution trick to avoid the patent. Anyway, we could do some thermocouple studies or other research to learn what is going on and learn if new features can help. In the meantime, YF will be testing a new guide material.

另外要注意的是，三菱制造了一款类似的发动机，但是他们的发动机有个辅助通道，将位于汽缸盖进气端的呼吸管内的机油转移到排气门导管顶部。这条通道是铝制汽缸盖上的一条凹槽，并且用延伸的汽缸盖垫片和金属罩来镶边。其中金属护罩就像是位于进气门弹簧下的延伸垫圈。3年前，因为专利问题的关系，我们取消了这种设计。工厂那边生产了一批500小时耐久的机器，并告知没有问题。或许我们可以从此事中了解到不同的地方或者有变化的地方。我们是否可以从进气端呼吸管的下方出一条小直径的管子，通到排气端的上方，或者用其他的方法来避免专利的问题。另外，我们也可以从一些热电偶的知识或者其他研究中找一下问题，看看有没有新方法能帮上忙。同时，耀锋也再尝试使用新的导管材料。