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28 Skater Repower--- 2.5 race to 300x's

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Old 06-01-2004, 07:03 PM
  #11
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Default Re: 28 Skater Repower--- 2.5 race to 300x's

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Keep us informed, Im thinking of doing the same thing.

Curtis
Okay Curtis...will do.

Warmest regards,

Rich
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Old 06-01-2004, 08:53 PM
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Default Re: 28 Skater Repower--- 2.5 race to 300x's

Hold on.......The Merc guys said you could shift a 2.5, when he did it They broke....Then he got the wink wink... well maybe you shoulndt shift these things. Whats the real story here, Anyone? What do they idle at? Would solid hub props be the issue/problem. It really seems to be a pain in the ass for him around docks.

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Old 06-01-2004, 09:06 PM
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Default Re: 28 Skater Repower--- 2.5 race to 300x's

2.5 race motors did not have neutral safety switches. 300X's do. The neutral safety switch actually shuts the engine down for a split second so the R's drop when shifting.
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Old 06-01-2004, 11:43 PM
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Default Re: 28 Skater Repower--- 2.5 race to 300x's

T2X after rigging my 30' motion I added lead shot ballast in the bow. The purpose was to stop the porpoising, Of course it did not fix that problem but the rough water ride greatly improved. I ended up with 4 25lb bags of shot way up in the nose. The speed lost was only about 2mph. Well I ended up building a tunnel tab , the porpoising was elimated and the boat handled the big water like a stern drive hull. Also with certain props top speed increased 1-2mph. I tossed the lead shot in the trash.
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Old 06-02-2004, 09:22 AM
  #15
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Default Re: 28 Skater Repower--- 2.5 race to 300x's

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Originally Posted by Shane
2.5 race motors did not have neutral safety switches. 300X's do. The neutral safety switch actually shuts the engine down for a split second so the R's drop when shifting.
Actually the 2.5 race engines DO have neutral switches.....most of the "smart" guys cut the leads to them..... when you do that you can't shift the units..... unless you slam them into gear..... maybe that is what we're talking about..... a poorly rigged set up. You must also have a good mechanic set your TPI switches so the engines idle at 8-900 RPMs or below. They actually purr like kittens...when done properly.

Tell your buddy to install his cut off switches properly and check his TPI settings.

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Old 06-02-2004, 09:49 AM
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Default Re: 28 Skater Repower--- 2.5 race to 300x's

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Originally Posted by T2x
Actually the 2.5 race engines DO have neutral switches.....most of the "smart" guys cut the leads to them..... when you do that you can't shift the units..... unless you slam them into gear..... maybe that is what we're talking about..... a poorly rigged set up. You must also have a good mechanic set your TPI switches so the engines idle at 8-900 RPMs or below. They actually purr like kittens...when done properly.

Tell your buddy to install his cut off switches properly and check his TPI settings.

T2x
OOPS! I stand corrected. Thanks Rich.
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Old 06-02-2004, 09:56 AM
  #17
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Default Re: 28 Skater Repower--- 2.5 race to 300x's

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Originally Posted by mmwalters
T2X after rigging my 30' motion I added lead shot ballast in the bow. The purpose was to stop the porpoising, Of course it did not fix that problem but the rough water ride greatly improved. I ended up with 4 25lb bags of shot way up in the nose. The speed lost was only about 2mph. Well I ended up building a tunnel tab , the porpoising was elimated and the boat handled the big water like a stern drive hull. Also with certain props top speed increased 1-2mph. I tossed the lead shot in the trash.
Your addressing two totally different problems......

1. C/G can only be addressed with weight distribution as it affects the boats stability when airborne.....(A properly balanced boat exits and re-enters the water with the same attack angle and does not "rotate" or drop the stern when aloft.)

2. Porpoising...is most often caused by transitioning from hydrodynamic lift to aerodynamic lift as the tunnel compression begins to lift the boat off of its sponsons without being fully successful. This creates a "hobby horsing" motion that indicates a speed range where neither compression nor bottom lift are fully in control. I agree that a tunnel tab (or a wedge) can be useful in correcting this. But, be very careful...... If the tab closes the tunnel in rough water..... or trips the hull upon re-entry..... the results could be disastrous. One of the items reviewed and not discarded after the Jesse James accident was the fact that the tunnel tab (a brand new item in those days) was in a fairly dramatic(15 degrees) down position ....... it also was quite long .......3 1/2 feet or so.


Be careful

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Old 06-02-2004, 10:46 AM
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Default Re: 28 Skater Repower--- 2.5 race to 300x's

Gearcases, shifting, cutouts and shift interrupters. The merc 2.5 and 3.0 motors use the same gearsets. The 3.0 has a larger exhaust cavity in the sportmaster, a different bolt pattern, and a 2 piece drive shaft.
These gearcases are very reliable. Most failures stem from rough water pounding the bearing carriers out of them. Shifting should never cause a failure, and as T2x has stated before, because they ratchet, exits and specially re-entry's hurt them a lot more.
None of the merc hi-per motors have a shift interrupter, this is used on the alpha sterndrives to momentarily cut the ignition while the gear change is being made. All motors come with a cutout, this feature stops the motor from being started in gear. It is a simple remedy, there are 2 wires both yellow with a red stripe exiting your key switch, they go to your shifter, cut and solder them together. This is your starter circuit, you can see where it ends on your powerhead starter solenoid. There is no reason to start your motors in gear!. Proper set up ( idle speed ) is key.

RT

Last edited by Firewalker; 06-02-2004 at 10:50 AM.
 
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Old 06-02-2004, 10:56 AM
  #19
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Default Re: 28 Skater Repower--- 2.5 race to 300x's

T2X Thank you for the advice. It is my goal to keep myself and my passengers safe. I am aware there are two different issues at work here. The ballast was a inexpensive experiment. The tunnel tab is very affective in eliminating the porpoising. I do have a indicator on the tab and motors. With very little down angle [maybe 5 degrees] rough water ride is improved as the hull lifts level.
Now get some more time on those new motors add post a full report!

Last edited by mmwalters; 06-02-2004 at 10:59 AM.
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Old 06-02-2004, 11:18 AM
  #20
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Default Re: 28 Skater Repower--- 2.5 race to 300x's

Quote:
Originally Posted by Firewalker
Gearcases, shifting, cutouts and shift interrupters. The merc 2.5 and 3.0 motors use the same gearsets. The 3.0 has a larger exhaust cavity in the sportmaster, a different bolt pattern, and a 2 piece drive shaft.
These gearcases are very reliable. Most failures stem from rough water pounding the bearing carriers out of them. Shifting should never cause a failure, and as T2x has stated before, because they ratchet, exits and specially re-entry's hurt them a lot more.
None of the merc hi-per motors have a shift interrupter, this is used on the alpha sterndrives to momentarily cut the ignition while the gear change is being made. All motors come with a cutout, this feature stops the motor from being started in gear. It is a simple remedy, there are 2 wires both yellow with a red stripe exiting your key switch, they go to your shifter, cut and solder them together. This is your starter circuit, you can see where it ends on your powerhead starter solenoid. There is no reason to start your motors in gear!. Proper set up ( idle speed ) is key.

RT

I love Canadians.

T2x
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