Good info. I didn’t know that motor height effected the holeshot that much. Makes sense though.
Which ones are good ones?

Steez, I ran my SHO with just one plug for years and never noticed any vibration. I also finally pulled last plug too and it still doesn’t blow out as long as I feather the throttle a bit on break over.

Hmmmm.

This thing shook hard. I went right back to the ramp and put the plugs back in. As for the blow out, I couldn’t feather it to get on pad. If I lifted the pedal a little, it slipped back down into the water, if I kept it going, the rpm’s shot up to 6500. Felt like a truck spinning it’s tires in the mud.

I've had 3 boats with Atlas and my current '22 boat has a Bob's and both perform very well.

You have something wrong besides the vent plugs

Could it be the hub kit?

Could be. I just know it's definitely not the vent plugs

I would check hub insert / kit, sounds like it's either the wrong one or thrust washer isn't letting it get torqued down completely and could cause the vibration

I’ll pull the prop tomorrow and check it. I have to stop at Ace and get more stainless cotter pins.

Thanks guys.

It’s not torqued down. I put it on. I just kinda snugged it up and stuck a pin in it. I read where it’s supposed to be much tighter. Duh I was thinking Yamaha prop kinda tight. Not hub adapter tight.

That could be the problem. Flo Torque is recommended 55 pounds torque.

I’m sure you know, but make sure you’re using a thrust washer made for the Yamaha. The Merc washer is a bit different and the prop won’t seat down properly.

I used the thrust washer from the kit. The Yamaha thrust washer is on the shelf with my old prop.

I did notice the new washer was shaped differently, but I followed the directions. I’ll check it all out this evening.

I’m a prop newbie. I just want to install it and go. I should know it wouldn’t be that easy.

steez, next time out (with all 3 sizes of plug) start with 3 med. and run it.

if it blows out or seems to not spin up quick enough adjust accordingly, you may need one of ea. size or 2 of one and one of another etc.

my tempests on the champion/johnson liked one solid one med and one small.

what size boat do you have, jackplate related.

put it on a hose and put it in gear you will see its the prop or hub not the plugs they have no effect other than hole shot

I pulled and yanked on the prop when I passed by the boat this morning. The prop wiggled a tiny bit. I know a tiny amount will be worse under load. I feel like y’all’s suggestions are getting me there.

I don’t have the correct hose “muffs” for a Yamaha. The ones I have are for my old Mercury. I think. Are they different?