150 TXRB Yam 2 stroke Carb Main jet sizes incorrect?

[joelisajer]

Maybe someone has already investigated this . . .

I've been tearing down and cleaning the carbs on my 150 TXRB. When I checked the Main jet sizes, I found that the Yamaha service manual calls for three different Main Jet sizes depending on the cylinder number (#150, #154 PU,PM, #158 PL) for my carbs. The parts manual only shows #142 for all six (leaner). Checking the carbs, I do have all #142 main jets. And all my floats were also at different heights the prescribed by the service manual (they were lower/richer). My question is why are they different from the parts webpage and the service manual? and which one is right? Does this have something to do with the EPA standard? If so would it be better to go to the richer jets?? The Carbs are Nikki.

[99yam40]

My C40TLRX has #115 jets in the top and bottom carbs and #118 in the middle carb.
Factory Manual shows it that way and they are in there when I looked.
Parts online show only #118. So I would go with the manual for your motor as long as it is a factory one. Does not make sense to me, but that is what the factory engineer wanted apparently.

[joelisajer]

My C40TLRX has #115 jets in the top and bottom carbs and #118 in the middle carb.
Factory Manual shows it that way and they are in there when I looked.
Parts online show only #118. So I would go with the manual for your motor as long as it is a factory one. Does not make sense to me, but that is what the factory engineer wanted apparently.

I can see that there may be need for different jets in different cylinder positions because of temp, flow, etc., but what confuses me is that the real Yamaha service manuals call for one thing and the real yamaha parts manual calls for another. . . which one is right??

[boats.net]

The manual may cover different models. The 150TXRB does use 142 jets, the Pro Series and VMAX models have the larger jets.