I have a Kawi 550 reed motor which runs absolutely perfect for the first 5 minutes and then it won't rev all the way up as high especially trying to accelerate from low speed. It just vibrates and bogs at a slightly lower RPM. As soon as you stop for a few minutes change nothing, then go out again it's perfect for the next 5 minutes and then the same thing. Changing mixture settings has no effect after 5 minutes either. It's like the spark plugs get too hot or something. I changed plugs and it worked great for up to 15 minutes and then no full rev up...just vibrating bogging at a lower RPM. I think the jetting is good. Why would this problem clear itself after a brief stop? The ignition box it completely dry. Do I need new boots? Here are the BR8ES plugs with about 4 hours on them:
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