I talk frankly, but my intention isn't to insult. While I'm not questioning either of your experiences, the personal and professional conclusions you've reached and the advice you're offering are fair game. As are my conclusions and advice. The best any of us can do is make our case. Though I'm skeptical of quoting years of experience to bolster a claim. We can all quote years of experience. Judgment is what's in question, not how many times a task was repeated over the course of a career. Again, no argument or hard feelings here. Just shooting it straight. Make your case and have it considered on its merits.
These suggestions were offered in this thread, so I believe this is actually the most appropriate place for at least one reply adding a bit of check and balance. I'm open to having a full discussion on either valve adjustment or maximum safe RPM, start a thread and I'll be there.
xlint: I disagree that over-revving was the cause of the engine failures. At most, RPM was a contributing factor that uncovered an underlying problem in both situations. Again we can get into more detail in a separate thread, but to sum it up: two failures with many other variables isn't a big enough sample size to outweigh the long track record of bone stock GY6 engines hitting 10k, 11k, and 12k every day under normal use. Every GY6 is capable of safely running these speeds with a stock 27/24 head from the factory.
shadow: If you re-read my reply, I was clear that valve adjustment is critical. My point is that valve lash is thrown around far too commonly as a cure-all suggestion, when it's rarely the actual problem. It causes new owners to do a lot of extra work, and has a lot of people inadvertently mis-adjusting their valves and compounding their problem. It should not be offered as a suggestion until other easier and more common problems are checked first.
If you guys want to start threads dedicated to these topics, I'm game. Or if you want to table it until I finish the dyno build, I think these are great topics to tackle and get some definitive data.
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Travis @ Buggy Depot
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