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Formula not up to speed. Help...

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Old 02-02-2010, 02:23 PM
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Originally Posted by Griff View Post
Things that need to be done.......................
Verify tach accuracy and speed accuracy
Check timing on both engines
Try a known good set of props
What are the drive gear ratios????

The boat should run about 40mph at around 3000 rpms
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Old 02-02-2010, 04:29 PM
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If the coupler is bad at high rpm, how do you even get on plane?
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Old 02-02-2010, 10:27 PM
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If it's a bravo coupler they don't slip. It is a all or nothing. You would see some shavings around it. here's two pictures, one was trashed, prop won't turn at all. The second one is close to failing but you could not tell at all. Worked just like a new one, but not for long.
You can see if the shaft turns it will trash the coupler, no way could it turn the prop and grab at all.
He's right...just replaced two shot couplers. They were completely trashed and had no idea....I was one or two hole shots from roasting them. When they go...they apparently just go. No halfway there. BUT...if he's willing to give you a free coupler....TAKE IT!!!!
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Old 02-02-2010, 10:59 PM
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He's right...just replaced two shot couplers. They were completely trashed and had no idea....I was one or two hole shots from roasting them. When they go...they apparently just go. No halfway there. BUT...if he's willing to give you a free coupler....TAKE IT!!!!
Ha... I was thinking the same thing!
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Old 02-03-2010, 08:34 AM
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Did you verify that both throttle linkages were giving you wide open throttle?
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Old 02-03-2010, 09:11 AM
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Make sure the slower engine is getting enough fuel. Check the fuel filter and water seperator, check for a plugged pick-up in the tank and make sure the fuel pump is working correctly.
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Old 02-03-2010, 09:39 AM
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I can easily reach the 5,000 rpm range on either engine without any hesitation (misfires, lack of fuel, etc). Seems like the power plants are generating the proper HP.

It almost feels like an automatic transmission in a car that is low on fluid(slippage). If the boat is running 35 and you back off the port side throttle you do not feel a loss of speed but if back off the starboard side you notice a drastic reduction of speed. On the other hand if you are running 4,000 rpms on both engines and push both throttles equally forward the starboard will move up to 4,500 while the port runs up to 5,200 so I have to back off the port to keep from red lining.
Hope that is as clear as mud...
Thanks guys
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Old 02-03-2010, 11:36 AM
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Make sure both drives are the same ratio.
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Old 02-03-2010, 11:48 AM
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Sounds like the port side is your problem, no speed loss and rpms raise faster.
I'd be looking for slippage somewhere. If the drives were a different ratio, I'd think the rpm difference would be across the board. But not sure if 1 would carry the other???

Try swapping the props.
Possibly try getting on plain with just 1 motor. Not actually doing that, but making 1 side work harder, so if there is something slipping, you'd think it would show up then.
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Old 02-03-2010, 01:37 PM
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Quote:
Originally Posted by 336Formula View Post
I can easily reach the 5,000 rpm range on either engine without any hesitation (misfires, lack of fuel, etc). Seems like the power plants are generating the proper HP.

It almost feels like an automatic transmission in a car that is low on fluid(slippage). If the boat is running 35 and you back off the port side throttle you do not feel a loss of speed but if back off the starboard side you notice a drastic reduction of speed. On the other hand if you are running 4,000 rpms on both engines and push both throttles equally forward the starboard will move up to 4,500 while the port runs up to 5,200 so I have to back off the port to keep from red lining.
Hope that is as clear as mud...
Thanks guys
When I had 4 blade bravo 1"s , I would have to stagger the throttles pretty far apart to run the same rpm above half throttle, went to 25 mirage"s and the problem went away.. Could be prop related.
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