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I just bought this 89 motor it had been sitting about 2 yrs. It started the first crank and idles good. It runs smooth but it only reaches 3700 rpm's and I still have about half the throttle left. It is on a 18.5 foot bass tracker with 13" by 17 pitch prop. Any ideas please.
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guy,
I don't understand what you mean by "it reaches only 3700 rpm and you still have half the throttle left"? If you are only giving it half throttle and the motor is climbing to that rpm, I would say that's pretty good.
If you mean it won't go any more than 3700 rpm at WOT, then it's probably because of clogged up carbs from being allowed to set up for two years.
Probably gonna' have to pull the carbs and do a carb rebuild with carb kit. You might try a shock treatment with Seafoam - scroll down thru the posts where I describe the procedure.
Or you might try pulling the high speed jets (main jets) and clean them, and squirt some Berryman's Chemtool into the orifices to clean out gum/varnish.
Get yourself a Yamaha shop manual to locate the jets - they are different on different models, but the main jets are usually under brass plugs located near the bottom sides of the carb bowls.
Good luck,
Ken K -
Thanks Ken. This is along the lines I was thinking of going first. Yes I mean that from half throttle up I get no more speed. I was told if you run very long without the carbs working properly the cylinders are not getting lubed and engine failure very possible so I need to get started. thanks for your help.Comment
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Hi gadget,
I'm new to this forum and just read your post. I had the same problem a few months back and was ready to do a teardown but luckily noticed a simple problem: The throttle advance lever/linkage was frozen from salt. Its located under the flywheel and for me was an easy thing to miss because I'm not much of a mechanic. I'm not even sure if "throttle advance" is the correct name for that linkage. Anyway simply disconncet the linkage and try working it. If it doesnt move or if it has popped loose from too much torque, dats your problem. Hope this helps.
TComment
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T,
Welcome to the forum, and thanks for the tip. That is something you really don't think much about, and it is pretty easy to check. I think the book refers to that as "magneto control linkage", I refer to it as spark advance linkage.
Good luck [img]smile.gif[/img] ,
Ken kComment
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Hey T,
Thanks for the advice, but I did check that first time out and the throttle is opening, but just not allowing any change. That is why my first thought was clogged jets. I did have a similiar problem on an old boat I used to have and it is eady to miss those type problems in that crowded outboard motor.
Ken,
I think I will try the sea foam first because if gas was not getting into the cylinders at all it would miss wouldn't it? It is not though it runs very smooth from idle all the way to 3700 but just won't go any higher. It is great to have good people to go to when you need help. Thanks again.Comment
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Ken,
can you tell me where to find your post on the shock treatment procedure please. Thanks in advanceComment
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guy,
Go to my post dated May 27, 2005 to "CLL" - thread is dated May 26, 2005 and is titled "water pump and maintenance questions".
Good luck [img]smile.gif[/img] ,
Ken KComment
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Hey Ken,
I finally did tear down the carbs and the bottom carb was stopped up. I had to work the float needle out because it was stuck. Now I guess only time will tell if there is any damage from not getting gas and oil in that cylinder. It is running very well right now though. Thanks for your help.Comment
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guy,
Thanks for the feedback - glad you got the old girl running good. What is your max rpm now WOT and trimmed out?
The best way to keep those carbs from getting gummed up again is to run the motor at least once a week, even if it is just with the earmuffs and garden hose. If that is not feasible and you have to store the boat for the off season, then follow the owner's manual for storage: fog the motor, fuel stabilizer, etc.
Good luck [img]smile.gif[/img] ,
Ken KComment
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