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Old 04-08-2016, 08:39 PM   #12
cheetah chrome
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Join Date: Apr 2009
Location: Melbourne Beach
Age: 49
Posts: 200
Re: Yamaha bogging down under load but idles and runs at speed no problem?????

When the carbs were cleaned did you/the tech do the link and sync procedure after? This sync your throttle plates together and throttle plates to your timing advance. If not at a minimum start there. Also try the easy stuff:

Drain the carb bowls into a clean catch can. Is there trash in the gas? Completely fix the source of the trash (deteriorating lines like others mention) or you'll just keep sucking it in.

Engine off, pump primer ball til hard. Does it stay hard? If not find where is the fuel going/fix.

Engine on, have a buddy pump the primer ball through the offending rpm range without choking it. Does it still bog out?

Test the fuel pump for a broken membrane (Google it...it's easy). A cough or sneeze can blow a hole in a membrane quickly. Since you have this bogging issue your more prone to having either one of those so your new membrane might be shot.

Since you are choking to get through that range it sounds like it's running lean at least in the given rpm range. Two strokes, even precision blends don't like to be run lean so try to figure it sooner than later. Good luck!

Last edited by cheetah chrome; 04-08-2016 at 08:48 PM.
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