2001 X18 Yamaha 150

[Tnfiremedic1]

Hey all, so I recently got a 2001 X18 with a 2002 Vmax 150, it had been sitting for a while. The first time I took it out I could only hit around 3500-4000 RPM, after cleaning the carbs and new plugs (plus water pump, oil change, etc..) I can hit close to 5500 easily and holds steady there. I understand 5500 is WOT for it, I am running a stainless 23M three bladed prop. I see guys hitting 60-65 with this set up, but with just me- 200 pounds and a light tackle load I am only getting 50, add a buddy and I'm only getting 45. The part that really makes me scratch my head is the previous owner was getting 62 with a heavy load out. I've played with different trim levels but no change, varying amounts of fuel, basically anything I can change I have tried. The fact I'm getting the RPM but no the speed sounds odd to me. Any idea why I cant hit these speeds? I'm getting discouraged because I know the boat can run faster than its doing now.

[Arkyarcher]

1. are you sure the tach is right(might not actually be turning 5500)
2. has it sat outside uncovered ( might be water logged)
3. what does the pad look like (if not flat it can keep the bow from raising)

[Tnfiremedic1]

I checked the tach with a voltmeter was around 200 of each other. It’s always enough garage kept and the pad looks great. Would a spun hub be a possibility? Maybe not “spun all the way”, I had a water pump act the same way on a different motor- would be fine all day unless I ran it up to the top end and it would start slipping and alarm.

[Arkyarcher]

Tring a different prop would seem to be a logical path. Does the motor sound change as it gets to top speed ?

[Cousin-It]

My old boat was 18.5 150 Merc and it would run 60-62 all day with a 23 Tempest Plus Call Marks Props he is AWESOME!!

[Tnfiremedic1]

So I was thinking today... could I just be a bonehead and over trimming?

[gixxer420]

I'm right there with you. I have a 05 x18 / 05 Vmax 150. When i bought the boat guy said upper 60's. I drove it and it would scoot. Then I started messing with jack plate. The motor was at 6 1/2 below pad. Had read where some say start at 3 1/2 and go from there. So I adjusted to 3 1/2 an lost alot of speed an running 48. I raised more and was getting slower. I said heck with it an dropped to 5 1/2 to 6 and I can get 51 - 54. I'm running a Fury 25p 3 Blade with 10" jack plate. The 60's would be so NICE

[Smallie_Hawgin]

There are quite a few variables to consider for sure... Prop (pitch, diameter, hub length and cup), setback, load (total weight and distribution), PTP measurement and then obviously making sure the motor is doing what it is supposed to be at WOT. If you are able to eliminate one question at a time, it can help... :)

[jimbliss]

I have the same boat and motor. If your rooster tall higher than the motor you my be blowing out causing too much hull in the water. They are sensitive to weight in the bow. Mine runs 57 at 5700rpm with just me and a normal load. I have a 6in jack plate and prop shaft is 5 1/2 below the pad and a 23m prop worked by Mark with extra cup. A larger jack plate and a higher prop setting might gain me some top speed but I prefer the a better faster hole shot.

[Tim Kelly]

You guys mean above pad don't you?

[Arkyarcher]

[gixxer420]

You guys mean above pad don't you?

No sir. Below the pad :)