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 Need help with new to me motor, 35 Vanguard 
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Joined: Sat May 26, 2018 1:21 pm
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Post Need help with new to me motor, 35 Vanguard
Bought a boat with mud buddy, 35 vanguard. Has the dual Mikuni carbs, doesn't run well above half throttle.

Took them down, cleaned them. Fuel is good and clean. Took off front cover, made sure all was clean and good around flywheel. Plugs are fresh.

Above 5/8 throttle it begins to run rough, almost like the advance is not right, if there is such a thing on this motor. In addition, I find there is a lot of unburned fuel misting in and out of the carbs when this is happening. The intake flanges are good. Im really getting aggravated with this. Setting the air screw on the carbs does very little at all.

I realize I bought something that may have been someone elses problem, but it idles well, doesn't smoke, has no blowby. Im stumped right now.


Sun May 27, 2018 5:38 pm
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Location: Cut Off, La.
Post Re: Need help with new to me motor, 35 Vanguard

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Mon May 28, 2018 9:14 am
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Post Re: Need help with new to me motor, 35 Vanguard
What size are the jets in the carb. Do a plug check. If the plugs are black while running at full throttle then you need to go to smaller jets. I have twins and I run 165 jets. They had 180’s they were too big. Your plugs should be brown, paper bad color.


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Mon May 28, 2018 4:42 pm
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Post Re: Need help with new to me motor, 35 Vanguard
This may sound funny, but one of my buddies had a similar problem and asked me to go ride with him. Went ride and it ran rough past half throttle. I loosened the gas cap because it was not getting any air and that fixed it completely. This may not be your issue, but hopefully something simple like that helps you. I know if you don't crack a built in gas tank, it runs like garbage


Mon May 28, 2018 5:06 pm
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Joined: Tue Jan 13, 2009 6:08 pm
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Location: Venice, La
Post Re: Need help with new to me motor, 35 Vanguard
Yep, could be starving for fuel Marpac fuel hose with the inner liner is notorious for collapsing at connection points. Id go through the whole fuel system checking for restrictions or air leaks in the tanks pick up tube, all connections, primer ball, filters, fuel pump, etc....

What exhaust are you running? I have seen the dual exhaust cause similar issues too. They have stamped tabs for outlet ports and over time the heat and exhaust pressure can cause them to close off. restricting flow.


Sat Jun 02, 2018 9:51 pm
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