Z-21 set up w/Yamaha HPDI 250

[Mbevins]

I have a 06 Z-21 w/a Yamaha HPDI 250. My question for those of you who also have this set up what are you running as far as prop to pad height? I’m running a 25T-1. What RPM are you turning at WOT? Thanks for the info in advance.

[Mullins057]

I'm running same prop and motor on a 2008 z21 intracoastal, seems top speed is 69-70 mph depending on load and water conditions at 5950 Rpm's. I have a 10 inch Bob's hydraulic Jack plate, at WOT, I trim it out and run the jack plate at 3 - 3 1/2, atleast on my boat seems to get squirrelly if I run it any higher. What number are you getting?

[zcomanche21]

I have a 2005 same set up. I was at 4 1/4 so I raised it gradually to 3 1/4 and it got a little squirrelly like Mullins057 said. So I lowered it to 4in and it runs between 67-69 depending on load. 10in set-back with the same prop you have. 4 in seems to be the sweet spot for me. Hope this helps.

[Mbevins]

What y’all are saying is about what I was getting. 68-70mph @ 5800-5900rpm. Had a new throttle cable installed for the hot foot and just seems to not be right. Struggles to hit 68mph and doesn’t seem to be getting above 5600rpm. Feels like it’s not getting the same bow lift as before. If I measured it right the prop/pad height is around 3.5” I haven’t moved that any. May just be the warmer water but I’ve run the boat for almost 5 years and it has always hit 5800rpm +. Gonna take it back to the guy that put the cable in and make sure it’s set right and not stopping on the engine before it hits the built in stop at the linkage and that the butterflies are opening all the way since I can’t see the linkage while pressing the hot foot pedal. Thanks for the replies

[Z21-I]

2007 Z21 Intracoastal 250 HPDI, 1st prop is a 25T1 5800-5900 and 69-70 GPS, 2nd prop is also a 25T1 but b and b 5700-5800 at 69-70 GPS. I have owned this boat for 10 years and those are the only props I have ever tried. I have been doing some research and would like to try a Bravo 1 XS or similar. Has anybody here tried one?

[Ky 520c]

Ran a 26” bravo xs on my 09 solo it would hit 71.

[danhrph]

I just bought a 2006 Z21 with Yamaha HPDI 250. It has a TH marine hydraulic jack plate and Tempest Plus 25p prop. I can barely get it to go high 50’s. Tach is showing 6000+ rpm. How do you determine the engine height with a hydraulic jack plate while running down the lake? Seems like 25p is what you are all running so could it just be the wrong prop? Might it be an engine issue vs a prop issue?


Definitely open to suggestions

[blkfalc4]

Need more info, mostly prop to pad.

Could be hub slippage, tach way off, motor issues, soaked boat, incorrect trim, lots of variables.

[zcomanche21]

Talked to Mark Croxton from Marks Props, he said the VMax series 25T1 is the best prop for my set up. I'm sending it to him for some repairs next week. I know the 2006 hull is a little different than my 2005.

[danhrph]

Need more info, mostly prop to pad.

Could be hub slippage, tach way off, motor issues, soaked boat, incorrect trim, lots of variables.

Prop to pad can be whatever since it's a hydraulic jack plate. Do you guys mostly find the right spot and leave it or do you jack up for takeoff and jack down once on plane? If you do the latter, how do you know where your sweet spot is while driving, aside from looking back at the jack plate while going 50-70mph lol

[blkfalc4]

In the end, yes you're correct. But p2p for performance and issues is another story. As this variable can cause unsuspected outputs.

[danhrph]

Compression is 80-90 on all cylinders