Prop issues

[einsteins]

Question for you prop smart guys...

Here is a pic from my merc monitor this weekend
Going downstream
Water temp was 74 degrees
Prop is a 24 pitch Tempest plus B&B by Croxton

Just seems like I should get more RPMs but cant
Boat is a Z7 with 200ProXS
Boat has 2 power poles Hydraulic JP
Running at 4.5 inches under pad (anything higher lost speed)

mercmonitor.jpg

Any thought on how I can get more RPMs and ultimately speed?

Thanks

[Nova Kaw 650]

Has speed/RPM's always been a problem with this set-up?

[einsteins]

When I first upgraded to the 200 (from 150) I only had 1 powerpole and I now have 2.
Run an Ultrex which is a bit heavier trolling motor than before.

Here is a screen shot of the boat set up as described before the additions
14296785322850.jpg

I was running a 25 fury then and moved to the 24 Tempest Pro to try and get RPMs up and see if speed improved.

[Savage]

The Poles and Ultrex killed your speed, there is really not much you can do to get it back, without removing those items.
The 25P Fury and the 24P Tempest run about the same RPM'S, thats why you didn't see an increase in RPM'S when you switched props.

If you want more RPM'S, then you need a 23P Tempest, but speeds won't likely increase, with your setup.

[mdtritn21]

Rpm's will go up as air cools in the fall but right now your doing pretty good for a 24 tempest.

[einsteins]

Should I look at getting a 23 pitch Tempest or Fury?

[lpugh]

I would recommend calling Ronnie Gilbert and talking to him about your needs 337 380 1437, a great guy and will give you the straight scoop esp if you want to run a Fury prop. I am also sure the Mark would treat you right as well, I just have no personnel experience with him. Ronnie really impressed me in what a fury prop is capable of, I used to be a diehard tempest guy.

[Savage]

Stay with Croxton……..23P Tempest for bow lift.

[einsteins]

Thanks all
I will give Mark a call as he has b&b both of my current props.

[skennedy]

One thing I would check before going any farther is checking your Thermostats . One little bitty piece of crap holding just one stat open will kill your top rpms and mph . My last pro xs I took mine out every time I seen a loss and every time there was a stick stuck in a stat . 2 cycle pro xs is real BAD about this . Especially If your running in river systems and lakes that have been recently Gone over pool.

[einsteins]

Funny you say that..... Didn't think much about it but I get a thermostat error every once in a great while on the MercMonitor, always while idling. Water pressure always looks good though and it is just a rare occurrence.

Is that something that has to be checked by a tech?

Thanks

[12many]

thermostats only function at idle.and low f
rpm. poppet valve opens at high speeds and u get unrestricted water flow. thermostats would hurt idle possibly throw a code.. but shouldnt effect top end.

at 4.5 btp your are buried. maybe wedges to get more trim?? does it run fastest trimmed max?
or have you tried lifting it a lot and trimming slower? I lose speed going up from 4.5ptp till I get near 4 then I just have to trim it slowly and it will wind out more. I run wedges as well .on a heavy nitro.

[einsteins]

Yes I get best results from max trim. I have a hydraulic JP and it runs best at 4.5" PTP If I go deeper it slows (I can go to 5.5 PTP with my JP) if I raise the JP it slowly loses speed as it comes up.

I dont remember ever lifting it much and running lower trim...

Thanks

[12many]

oh sorry I read it u had a manual jp..hydro takes the guess work out

[12many]

maybe wedges?? helped me not lose speed adding battery and talon

[Wisfarmer]

I ran 26 tempest on my z7-200 same as yours no poles but ran 71-72 at 5800 check your hotfoot

[Wisfarmer]

I also ran mine at 2.75 below pad was worked by croxton something with us prop ain't right send to mark tell him to b&b and add as much cup as possible so u can run it higher

[einsteins]

Just got the boat back from the Shop

What they found, from the work order

Leak Down Test
#1 8%
#2 12%
#3 10%
#4 6%
#5 11%
#6 14%

Air/Fuel Pressures OK
Replace spark Plugs
Clean wood from port Thermostat housing
Checked Blow off Valve for debris - OK
Plug gas was .040 +or-
River test 5650 RPM at WOT

I will have it out tomorrow and see if it is better
The fact that he got 5650 RPM on the Merc Monitor is promising.

Stay tuned.

[Savage]

Just got the boat back from the Shop

What they found, from the work order

Leak Down Test
#1 8%
#2 12%
#3 10%
#4 6%
#5 11%
#6 14%

Air/Fuel Pressures OK
Replace spark Plugs
Clean wood from port Thermostat housing
Checked Blow off Valve for debris - OK
Plug gas was .040 +or-
River test 5650 RPM at WOT

I will have it out tomorrow and see if it is better
The fact that he got 5650 RPM on the Merc Monitor is promising.

Stay tuned.

There is no such device as a "Blow Off Valve" on ANY Mercury Optimax…….Better have the technician explain this one!

[Nova Kaw 650]

There is no such device as a "Blow Off Valve" on ANY Mercury Optimax…….Better have the technician explain this one!

Likely the poppet valve, based on "checked it for debris".