75hp Merc Inline 4 help needed@

**Hippie459MN** · 09-22-2021, 05:31 PM

Just a little update, this past Saturday we hit up the lake for a short bit and the boat never died on us. So it was either the ignition trigger, or the stator, or a combination of both. I just did a base line on the carbs when I put them back together and now it idles a little wierd in the lake and has a low end bog that was never there before so the carbs will need some tuning. But...

My kid set up the GoPro on the motor of the boat when we took the Vixen out and this is a little something that we got. We were out there for about 30 minutes. It doesn't look that bad in the video but the water was so rough we called it pretty quick. It was beating us up pretty good. Carbs need some tuning but other than that, thing gets up on the pad so fast and easy. I have all the stabilization turned on on the GoPro so it looks like we are all over the place worse than we were. I'll fix that so the horizon stabilization isn't on next time. Also, I think the GoPro's GPS reads slow. I had two other GPS devices read 53.2mph and it seemed like it didn't sync with the video real well it seems. It showed us slowing down well before I let out of it. LoL Also, this is my kids YouTube channel so if you could give it a sub that would be awesome! He will be putting all the Hydrosteam Vixen related stuff on there. Plus, he needs more subs to unlock a few things in YouTube. And don't mind my awful hat hair going on. haha

My kid did all the editing and stuff.

**Mark75H** · 09-26-2021, 07:28 PM

AV gas does nothing for these motors, they do not have high compression and there are no magic ingredients in AV gas. You can run them 7,000 but you will be well out of the powerband. The motor makes max power in the high 5,000 area. After that you are going back down. Prop it for just under 6,000 and you will get the best speed.

**Hippie459MN** · 10-02-2021, 01:53 PM

Originally Posted by Mark75H

AV gas does nothing for these motors, they do not have high compression and there are no magic ingredients in AV gas. You can run them 7,000 but you will be well out of the powerband. The motor makes max power in the high 5,000 area. After that you are going back down. Prop it for just under 6,000 and you will get the best speed.

I just run non oxy 92. No AV gas here. And thanks for the tip on the RPM range. The tach that is in the boat now doesnt work (was in the boat when I got it) but I have another one here I know works so just have to switch them out. While im on the tach subject, what setting on the back of the tach should I have to for the 4 cylinder? 2p/4c, 3p/6c, 4p/8c, 5p, or 6p? Im going to assume 2p/4c.