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 RPMs 
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MMT Pro Member

Joined: Tue Aug 02, 2016 1:32 pm
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Post RPMs
Finally got a tach for my 35 HP GDSD with a mikuni and dual exhaust. Running it this weekend on the river I would get to about 1/2 - 2/3 throttle and about 3900-3950 RPM and then it would start cutting back. It also feels like when I get the RPMs up that high the prop is slipping. If I remember right, the prop is about 11" across, but I'm not sure what Godevil's props measure when they are new. I'm getting maybe 20 mph in a 1644 with 3 guys and a 50 lb pup (about the same as what I get with just me and one other guy). Any help? I don't want to start buying stuff before I know what the problem may be.

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1644 GoDevil 35 hp GDSD


Mon Jul 15, 2019 7:16 am
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Joined: Thu Nov 04, 2010 7:38 am
Posts: 4323
Location: Cut Off, La.
Post Re: RPMs
Sounds like your carb may not be tuned correctly if you start losing rpm's when full throttle.

But it also sounds like you are maxing out the load in the boat and the motor.
3 guys is a 16x44 is just about pushing it.

Even though you have a carb and exhaust, you have no headwork to help.

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Refurbishing a Prodrive


Mon Jul 15, 2019 7:37 am
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Joined: Fri Jan 10, 2014 1:16 pm
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Location: Gladewater TX
Post Re: RPMs
Agreed. Mikuni with stock heads is a lot of carb


Mon Jul 15, 2019 7:59 am
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Joined: Fri Dec 18, 2009 8:10 pm
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Location: Rowlett, TX
Post Re: RPMs
Slide could be over-travelling.

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Mon Jul 15, 2019 10:13 am
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Location: Tarkington, TX
Post Re: RPMs
4300 CDI coils? worn prop?

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Mon Jul 15, 2019 10:20 am
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Post Re: RPMs
I have no idea on coils from what I understand everything is stock outside of exhaust and carb. Prop is worn I thought that might have something to do with it.

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1644 GoDevil 35 hp GDSD


Mon Jul 15, 2019 11:41 am
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Post Re: RPMs
Could very well be a worn prop like marcus said


Mon Jul 15, 2019 3:02 pm
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Location: SW LA
Post Re: RPMs
I think your rpms are fine. I Believe your maxed out with that load and size boat. I could be wrong, but with a stock 35 GD in water you’re always gonna be around 3750-3900. GD props new are 11” across.

I’ve got heads cam exhaust and with the load your describing I’m running 3800-4100. Anymore and I lose speed. I also have a burnt prop that measures 10 1/4- 10 1/2. I have a 17x44 alweld and I imagine your boat is heavier than mine. Unless yours is an old one it could be .100 gauge


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Mon Jul 15, 2019 6:58 pm
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