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Discussion Starter · #1 · (Edited)
Hello,

We just purchased a Yamaha '05 RX-1 4-stroke and took it to a shop for a tune up and it got a clean bill of health. Now that we got some snow we wanted to take it for a spin, it doesn't want to stay running. It starts up and idles through the warm up period no problem. When you give it gas, it accelerates great but then after 10-15 seconds bogs out and dies.

Between taking it to the shop and testing it out, we filled the tank completely with 91 octane gas (it must have been almost empty). I've now learned through the threads that the machine prefers to run on 87 octane gas.

Does it make sense that as I throttle up, the higher octane gas can't ignite fast enough causing it to bog out and shut off? Or do you think there is a separate issue?

Thanks in advance,
Rob
 

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The 91 octane is definitely not your problem. Sounds like it's not getting enough gas. I'd look at carbs or fuel pump.

Sent from my LM-V405 using Tapatalk
 

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Agreed would be looking at carburetors, fuel pump/s, clogged fuel filter and if there is an ECU any codes as well. Never in my life have I heard that higher octane gas can't ignite fast enough. Dad made that stuff for close to 30 years so I've heard just about everything with regards to gas but that line is a whole new one!

FYI OP gas regardless of octane or E-85 gasoline ignites the exact same. Idk where you heard that BS or who online is saying it but they are so dead wrong.
 

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91 technically takes more energy to ignite and burns slightly slower, but... none of that would cause your problem. My sleds both run 91 all the time, because anything less than that in my area is e10 based. (and yes, they actually do prefer 87 and have been proven to run better, but given the choice of 87 e10 or 91, run 91!)

Does it restart after it dies? If it is a pain to fire back up, you carb bowls are empty, so it is a fuel delivery problem. Easy to test, you have 2 fuel pumps, take the outlets off and let them dump into a container while cranking. Should get a pretty healthy flow out of both. Probably a plugged filter, pumps don't fail that often, and when they do, they don't pump anything. On the RX, 1 pump handles 2 cylinders, another handles the other two, they don't share the pumps in any way.

If it is easy to restart, your carbs probably need cleaning. High speed jet is clogged and not delivering fuel. (could also be a torn rubber diaphram on the top of the carb)
 

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Discussion Starter · #5 ·
Thanks everyone for your insight. It starts up no problem after it stalls. Also note that when it stalls there are no codes and the dash looses all power.

I spoke to my mechanic that looked at it and he suggested it could be a bad electrical connection else the computer would have stayed on after the stall.

Going up Saturday. Will try your suggestions and hopefully get to the bottom of it.

Thanks again.
 
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