I used the Joe Reeves WOT spark advance setting method on my 115hp Johnson. I did the same on a 25hp, but in that case because the boat only went 24mph at WOT, I could "safely" also check it on the water running at 24mph. I found that the spark advance was off the target and I adjusted it accordingly. I'd like to test a 70hp and my 115hp on the water, but they go too fast at WOT.
I saw some boat yard test tank videos on YouTube and it just looks like they made a boat ramp and back the trailer into it. Can I just back my trailer into a boat ramp and do a WOT test to verify the spark advance is OK? If I strap the boat onto the trailer and leave it hitched to the truck, will the boat thrust break the trailer winch post and hit the truck or something? I look at the videos and do not see much thrust/push forward on the trailer and they are running even big twin engines.
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