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forresj
MMT Pro Member
Joined: Tue Aug 02, 2016 1:32 pm Posts: 52
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![Post Post](./styles/acidtech_tiger/imageset/icon_topic_latest.gif) 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.
_________________ 1644 GoDevil 35 hp GDSD
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Mon Jul 15, 2019 7:16 am |
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brycecheramie
MMT 1000 Club
Joined: Thu Nov 04, 2010 7:38 am Posts: 4323 Location: Cut Off, La.
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![Post Post](./styles/acidtech_tiger/imageset/icon_topic_latest.gif) 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.
_________________ Refurbishing a Prodrive
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Mon Jul 15, 2019 7:37 am |
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Will C
MMT Sponsor
Joined: Fri Jan 10, 2014 1:16 pm Posts: 2107 Location: Gladewater TX
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![Post Post](./styles/acidtech_tiger/imageset/icon_topic_latest.gif) Re: RPMs
Agreed. Mikuni with stock heads is a lot of carb
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Mon Jul 15, 2019 7:59 am |
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cb5331
MMT Super Elite Member
Joined: Fri Dec 18, 2009 8:10 pm Posts: 16915 Location: Rowlett, TX
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![Post Post](./styles/acidtech_tiger/imageset/icon_topic_latest.gif) Re: RPMs
Slide could be over-travelling.
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Mon Jul 15, 2019 10:13 am |
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MaXXis85
MMT Elite Member
Joined: Wed Jan 14, 2009 7:23 am Posts: 6233 Location: Tarkington, TX
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![Post Post](./styles/acidtech_tiger/imageset/icon_topic_latest.gif) Re: RPMs
4300 CDI coils? worn prop?
_________________ Bayou Surface Drive 337-351-0362 Tarkington, TX 77327
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Mon Jul 15, 2019 10:20 am |
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forresj
MMT Pro Member
Joined: Tue Aug 02, 2016 1:32 pm Posts: 52
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![Post Post](./styles/acidtech_tiger/imageset/icon_topic_latest.gif) 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.
_________________ 1644 GoDevil 35 hp GDSD
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Mon Jul 15, 2019 11:41 am |
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Wchauvin
MMT 1000 Club
Joined: Sat Sep 30, 2017 7:10 pm Posts: 1872
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![Post Post](./styles/acidtech_tiger/imageset/icon_topic_latest.gif) Re: RPMs
Could very well be a worn prop like marcus said
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Mon Jul 15, 2019 3:02 pm |
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kirk
MMT F.E.
Joined: Thu Apr 18, 2013 5:52 pm Posts: 870 Location: SW LA
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![Post Post](./styles/acidtech_tiger/imageset/icon_topic_latest.gif) 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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