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115 yamaha 2 stroke, runs rough wont go over 1500 rpm

J

Joessabre

New member
I have a 1987 crestliner Sabre with 1987 yamaha 115 hp 2 stroke . Took the boat out this afternoon and boat would not go over approx 1500 rpm in gear . In neutral it idles as normal and can rev up to 3000 rpm but sounds like it's missing. Then I trimmed up the motor a little, went to accelerate and ran well got it up on plane with no problems and ran it like that for 3 to 4 mins thought the problem was fixed . I slowed it down put it neutral, turned it off and back on .Then the same thing happened as before and couldn't get it past 1500 rpm in gear would stall . The carbs were overhauled and new fuel filter, fuel line and bulb . Any ideas ?
 
1st.....never ever never ever run up ur rpms in neutral. Any thing above 1500 and ur asking for trouble. Doing so provides no diagnostic value or outcome, thus is useless.

When in gear ear and throttling up if the engine sounds deep throaty then this is fuel related, most likely clogged jet(s). Pull carbs, pull jets, soak, clear....check floats to spec, reassemble.
 
ClassicAQ said:
1st.....never ever never ever run up ur rpms in neutral. Any thing above 1500 and ur asking for trouble. Doing so provides no diagnostic value or outcome, thus is useless.

When in gear ear and throttling up if the engine sounds deep throaty then this is fuel related, most likely clogged jet(s). Pull carbs, pull jets, soak, clear....check floats to spec, reassemble.
Click to expand...

Yup your right I should of never run the engine that high in neutral. I did have the carbs pulled apart and soaked in seafoam/ gas as the carbs were gummed up then reassembled . The same problem persists , when I throttle up in gear it sounds like it's only running on a couple of cylinders then it cuts out and doesn't sound throaty . The mechanic I'm using seems to think electrical problem as its intermittent any other ideas would be helpful.
 
Did pulling carbs apart also include removing all jets, clearing orifice? Hold each jet up to light...u shud be able to see thru. Fuel system accounts for 90% of all ob motor issues. Advise not to move on to compression or spark until you've r/o fuel system.

With that said, compression test and metering coils are quick and simple diag tests.
 
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