2004 champion 187cx won’t stay on pad

[JesseJames28]

I recently bought a 04 187cx with a 04 Yamaha 175hpdi. Pro=3.5” prop= 25-M 10”slide master jackplate.
The boat seems to have a hard time staying on the pad when running at higher speeds. It will get up and then suddenly drop the bow. If I let out a little the prop will bite and pick the nose back up. It slings a rooster tail about 3’ higher than the motor when it drops the bow. All this occurs at 3/4 trim according to the gauge. I also haven’t been able to get it any higher than 5200rpm and 63mph since I bought it. Any suggestions?

[SCOTT196]

need your prop worked , its lost the cup.

[STLBassBuster]

Try dropping the jackplate to 3.75-4”.

[Tx Champ]

I'd check to make sure your motor is 100%, that the 25M isn't too much prop. Run it by Yam911 n the Yamaha forum. He's a tech in the GA area.

[Lea]

Try dropping the jackplate to 3.75-4”.

I agree with this.

[JesseJames28]

I'm going to drop the plate to 4" and run that and see how it does this weekend. I've got a 23p tempest on its way to Mark's to get repaired, when I get it back Ill send the 25M to him to get reworked and possibly look for a 24 or 25 tempest to try out. I've read that most of the guys with this setup are getting mid 60's on average out of it. Anybody know what the compression spec for this motor is?

[JesseJames28]

So I dropped the motor to 4"ptp and ran it with the freshly repaired 23 tempest+ and the hull still refused to lift (52mph @ 5800rpm *massive rooster tail at anything above 1/2trim). Lowered the motor to 4.5"ptp and it would lift for a second if I got it opened up and then quickly throttled down a hair, but then it would drop the bow when I tried to accelerate back to full throttle (52 mph @ 5900rpm). Swapped it over to the 25m prop at 4.5" and the hull lifts as it should rpms @ 5200 running 62mph with full trim (roostertail level with the top of the cowling). Might move the motor back up to 4" ptp and run it with the 25m and see how that does but I'm worried it's just going to run back into lifting issues again, really wishing I had a hydraulic plate at this point. Am I expecting too much from this setup?

[pastormark]

I run a 175 EFI on a 1999 187 and 62-63 is about normal. 4 inch below pad. Good lift at 58.5 rpm's. I had my prop worked by Mark Croxton last year and it helped a bunch.

[Almag6]

take your boat to a scale and weigh it. might be waterlogged.
Any transducers in back disrupting flow to prop?