Carburetor question Yamaha 100hp 4 stroke
 

Looking at a boat with a 2000 100hp yami that has carbs and isn't fuel injected. Motor has 165 orig hours. Last owner didn't winterize boat and it sat for 2 years. The guy who has boat now had carbs rebuilt with factory parts. Runs fine at high RPM's but has issue running at low RPM's and motor coughs a bit. Mechanic said boat has to be run under load to break carbs in. Long story short.... Anyone have experience/advice with these yami's? Trying to decide if its worth buying, or will it always be a problem.

Maybe Tebow can fix it. :rotf2:

Yea he usually fixes everything !!! Lol
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#^&#^&#^&#^&y and I just picked up a boat with around the same year engine with about the same hours (it's a 140).

It runs fine at low speeds. I don't think that the carbs would need to get "broken in"

Aside from that, the engine seems pretty awesome.

Check the fuel system for air leaks

ck for leaks as stated, change all filters, new gas (is it 2 years old?) new plugs. I would also put some marvel mystery oil in plug holes and let sit for a 1/2 hour then start and run, will lube and losen any rust and stuff from sitting for 2 years not winterized.
I always ran yamaha and they are great motors!!
Good Luck!

Thanks for the info much appreciated
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carbs do not need to be broken in.... I hope the guy that said that didn't do the rebuild.. because he's certainly no mechanic... check to see if the idle circuit is fixed or adjustable.... if it's adjustable, turn each screw counter clock wise 1/8 of a turn ( rich) and your idle issues will most likely go away( I'm avoiding the entire procedure here on how to properly set up a carb)... other wise you'll need a proper rebuild... this all applies after you've done the checking the others have recomended... to check for vacume leaks, spray storage seal around the base of the carbs and along any maniflod gaskets... if they are leaking the engine RPM will change dramaticly.. storage seal ( or engine oil) is the safest thing.. in the past people used to use starting fluid... not a good idea...

the early carberated 4strokes were a little notorious for being tough to get fine tuned..... had one on a 18footer that used to give me fits

almost impossible to tune these without a vacuum gauge. I have managed to get them to idle very well once set up right with the proper setup. if they sat with bad fuel in them for two years then they will need to a good long soak in some carb cleaner, then a thorough rinse and dry. linkage will need to be adjusted and properly set.

as far as carbs needing to be broken in whoever told you that needs to lay off the crack pipe...