Slow speed jets

I need to locate the slow speed jets in the carbs for a 2004 Yamaha 150 2 stroke. I think I saw the name Nikki on the carbs.
I have had problems with junk in my fuel tank and cleared that up. Now after installing a racor fuel/water filter and cleaning the carbs out, the moter ran great midrange and top end.
The engine doesn't idel well or run smooth at slow speed. It coughs back through the carbs and stalls. If I bump up the rpm's it clears up. Pretty tough coming into the dock and lose the engine when you need it.
I also have put in new plugs.
Any one have any input on this

Thanks
Shorty8388

[jb123]

may just need to sync carbs

[Hamfisted]

Through the bottom of the carb bowls...

After '97 they moved the low speed jets to the center of the lower carb body, instead of the outside lower corners of the bowls. You can access them through removing the brass plugs on the very bottom of the bowls, but this requires removing the carbs again. The old carbs had the idle jets on the outer lower corners of the bowls and you could access them without removing the carbs. They required frequent cleaning if the engine sat for any length of time without being run. The newer design was suppose to help eliminate that, but oh well... If you can find a can of Amsoil PowerFoam you can use it to clean the jets without having to remove the carbs. Just remove the main jet from each bowl and spray it up into the bowls through that opening, it will foam up into all the orifices and clean out any gum or varnish hiding up in there. But other than that you're gonna have to pull the carbs off. Use a good carb cleaning spray like Berrymans Chemtool spray (Walmart) to flush out everything. Remember, when you spray in one orifice you should see the spray exit through another one downline. You can fish a piece of stainless leader wire up into the jet orifice to make sure its clear too. Good luck.




-Mike

[ctbeacher]

Take a look at my thread: 90TLRY Prime Start clog and Speed Bog Down for hopefully some helpful information about a similar problem.

I am not sure about the jet locations, but both of the jets on my carbs could only be accessed for removal by removing and disassembling the carbs.

You could try draining the bowls and squirting carb cleaner in the bowls, then running a separate 6 gallon tank with a healthy dose of seafoam in it to see if it will fix it. Not much effort to see if a chemical fix will work. I do suggest draining the carb bowls first to see what gunk is floating around in them. If you see stuff, you at least know that is probably your problem.

[ctbeacher]

Also, to rule out a fuel restriction problem, have someone pump your primer ball at idle to see if things improve. I re-read your post and noted that the problem occured after you rebulit the carbs and installed a Racor filter. So make sure the engine is not starving for fuel at idle because of the addition of the filter.

Lastly, are your idle jets set properly? (To the correct number of turns out from seating - per the Yamaha specs for your carb?)

Just a few more options.