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Discussion Starter · #1 ·
Having trouble with my 1998 year 115 Yamaha and wanted advice on what to try next. The issue is that it won't idle/run well at low RPMs. It starts right up (out of gear and with the throtle to about 2000 RPMs) but when you slow it down (take it out of neutral to put it in gear) it tends to stall.

I do not think the problem is bad gasoline or dirty carborators - I have replaced gas and cleaned the carborators last weekend. It runs better now that I have cleaned the carbs, but the problem remains.

It runs great down to about 1400 RPMs, but below that it is having issues.
I think it is supposed to idle around 900 RPM's, but not sure about this.

Any suggestions are appreciated!
 

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I think there are high speed jets and low speed jets in those carbs. Sounds like a low speed jet could be a culprit? How you go about diagnosing that, I don't have a clue.
 

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Run your engine , when it starts to die if you have a choke activate it. If no choke then put you hand over the carb throats. If the engine picks up and keeps running, then you need to go bak into the carbs.
 

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Discussion Starter · #5 ·
As you idle down (below 1100 RPM) and it begins to die, it will come back to life if you give it a little choke.

I am not an idiot but I'm certainly not a great mechanic either - do you think I should run another can of carb cleaner through it? Need to adjust idle speed?

Thanks
 

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I think there is still an issue with the carbs. such as a dirty low speed jet or something blocking the idle circuit. Fac. spec on idle speed is 750=-50 in neutral 650 in gear
 

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yamaha carbs have a lot of small passages in them.if the carbs are varnished up nothing in a can is going to clean them.they'll need to be soaked in serious carb cleaner overnight.
 
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