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loose needle valve on Magnum 91 4st

Old 10-31-2016, 02:59 PM
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Default loose needle valve on Magnum 91 4st

magnum 91 4 stroke w/ approx 1/2 gallon through it (wildcat 10%) runs great with the needle open about 11/3 to 11/4 turns out I thought that would be a real lean setting, but it's only 170-180 at the exhaust outlet. problem is, the needle is so loose in the inlet, it will slowly richen from vibration to the point it dies. the only contact seems to be the o-ring on the needle; the bore of the inlet is bigger than the dia of the needle I can wriggle the needle back and forth at any setting I tried a piece of fuel line over the bore, but the length of the bore is too short for it to stay on. maybe a dab of permatex on the undersized dia of the needle above the o-ring? something to give it some friction so it will stay where I set it. anybody have any ideas, I would welcome them. thanks Dave
Old 11-01-2016, 12:31 PM
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get a new o ring for needle and slightly larger one to go around the outside of the clicker and needle. this keeps vibration down and holds needle in place,
Old 11-02-2016, 06:03 AM
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I am not sure what it looks like, but we used to add a drop of red locktite to the threads so it would not wander. Only a small carefully placed drop on only the threads. The female thread being cleaned with acetone or laquer thinner, and a bit of wax on the male thread so it would still turn after breaking free initially. Too much Loctite, and you will be in trouble.
Old 11-03-2016, 07:20 AM
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Sounds like your engine cam without the detent or clicker? I can't find one on their website, but they generally use the same part for almost all engines. An OS detent may also fit.
Old 11-05-2016, 06:41 PM
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the fix is in,

read reply #11 in my link below, if your engine uses the same carb as the 91 then it should be the best and only fix to do, I have a Mag 180 4St, I will try it on mine


Last edited by the Wasp; 11-05-2016 at 06:50 PM.

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