Bought a boat need help

Airboat propeller discussion.
tlanie
Southern Airboat Member
Posts: 2
Joined: Wed Jul 26, 2017 2:39 pm

Bought a boat need help

Postby tlanie » Wed Apr 11, 2018 11:28 pm

Hello, I live up here in Minnesota and have always wanted a airboat. Last summer we purchased a older Cotton mouth with a 4 cyl Lycoming engine and a wood prop. The boat runs great, starts right up and runs out at probably 35 mph or so. The problem I am currently having is shutting it down. I have checked and bypassed the ground wires to the mags still just sputters but won't shut of until I kill the fuel pump and wait for it to run out then kill the mags. Another thing I am looking for is recommendation on a prop upgrade, any input you might have throw it out. I am very new to airboats and am probably the only owner in Minnesota so not much help up here.

flcracker9
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Site Supporter - III
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Joined: Mon Aug 11, 2014 10:05 pm
Location: Loxahatchee

Re: Bought a boat need help

Postby flcracker9 » Thu Apr 12, 2018 7:59 am

If the mag switches are working and grounding the mags, sounds like maybe a timing issue? Are you running AV gas? based on your description, still sounds like the mags aren't grounding. I'm sure others will chime in.
12' Open Palm Beach, IO-0470-L 260hp, 72" NGQ

Leatherneck76
Southern Airboat Member
Posts: 2
Joined: Fri Jul 31, 2015 11:30 pm

Re: Bought a boat need help

Postby Leatherneck76 » Thu Apr 12, 2018 9:43 pm

When you say " it Won't shut down" ; I'm curious if you have tried stabbing the accelerator with the mags grounded (off) to see if it will tach up or stall. If it tachs up and runs smooth; then it's probably not a timing issue and you need to take the points cover off the mag and triple chech your ground. If it kills it or backfires and dies I'd say your timing is too close to tdc. Also try starting it with the mags off on a cold engine if it won't start your mags are grounding. Then try starting it on a hot engine with the mags off. Then consider that you have to check your ground while it's running sometimes when a engine is running and creating a vibration your ground could be intermittent

tlanie
Southern Airboat Member
Posts: 2
Joined: Wed Jul 26, 2017 2:39 pm

Re: Bought a boat need help

Postby tlanie » Thu Apr 12, 2018 10:53 pm

Thanks. I will try your testing advice and repost what happens. Boat is still in winter wrapper. We were going to get it out this week although we now have yet another winter storm heading in 12 to 18” on the way no open water for a couple weeks yet. Winter is getting old.


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