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Tune and clean

Jester

Member
Messages
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Boat Make
Sugar Sand
Year
1996
Boat Model
Mirage
Boat Length
NA
My mercury 120 won’t get up to speed just under plane speed any one have this issue also how can I run the eng while on the trailer Any recommendations on carb cleaning
Send help
 

tdonoughue

Jetboaters Admiral
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Location
The Woodlands, TX 77381
Boat Make
Yamaha
Year
2012
Boat Model
AR
Boat Length
24
Don't have experience on your carb specifically, but have rebuilt several on cars. It can be a big job to do a full rebuild. Requires you to take your time and watch for springs and balls and things that are beneath ports.... Usually took me 1/2 to a full day. If you are needing a carb cleaning, you can sometimes get by with some external carb cleaner squirting, but usually that is just temporary and you will wind up breaking down the whole thing. A carb rebuild kit will have new seals and small parts that should be replaced during the rebuild.

Pro tip: Don't clean the removed carb with carb cleaner on an asphalt driveway. Carb cleaner eats asphalt. Duh...

All that said, my usual advice with any jet boat having trouble getting on plane or up to speed is to start with the jet. How is the impeller? Anything blocking or causing cavitation in the path of the intake? A chewed up impeller or missing caulk or open seams more frequently mess up jet performance (and more frequently than a poorly running engine).

Does any of that help?
 

Beachbummer

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Location
Houston TX
Boat Make
Yamaha
Year
2008
Boat Model
SX
Boat Length
23
I second my personal difficulty cleaning/rebuilding carbs to perfection. My old boat had a single cheap carb per engine ($199), so I would replace it instead when needed. Maybe find a local motorcycle shop willing to rebuild. It was such a pain to remove and reinstall, only to find the cleaning job was not perfect....I gave up. I hope if you undertake the job, you have better luck than I did.
 
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