I have a 225 ox66. I have noticed after i run the motor in the higher rmps.(5500) when i am fast idling up to my fishing spot the motor seems to have a slight backfire,more like a hichup.I have had it checked and replaced the sparkplugs.and it still does it.Ihave run ring free in since the day I bought it 8yrs ago and recently started running stabil and it still happens. other than this the motor runs good.If anyone has any ideas on what this could be please let me know.
Thanks Botto
Could be excess carbon causing pre-ignition. I would try the maximum shock treatment with Ring Free to attempt to clean it up. I would also add Sea Foam to the fuel instead of the Sta Bil for a while, also. If you read some of the other threads, some of the guys are using sythetic oil now instead of Yamalube and reporting good results with less carbon, but I have not tried it yet myself.
Sounds like a lean sneeze to me. TPS adjustment and if you haven't done so clean and flow test injectors.
Thanks for your advice on my yamaha.Could you explain a lean sneeze to me please?
Thanks Botto
Lean sneeze is pre-ignition. Typically caused by not enough fuel (lean injector), excessive carbon build-up on piston tops, low octane fuel or timing advanced too far. Making one or more cylinders run hotter than others. TX Larry has a good point about type oil used and de-carbing the motor. Check spark plugs to identify if any cylinders are lean. +.01v on TPS.
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