Yamaha Flywheel

I have a 115 2003 Yamaha I have Boyesen reeds, Hydra-tech rec heads and larger jets everything else is stock. The above change gave me a lot more torque. Will adding velocity stacks help any if so do you know anyone that makes a set that will fit this carb 2 bar. motor. Would it be worth installing a 130 exhaust tuner? I am running stock ignition timing any gains made from more timing at idle?  Is it worth installing a lightweight flywheel on a 90 HP or 115 HP Yamaha that has minor modifications? What would be the best one thing to do to a stock 90 Yamaha for more power? 

Thanks for any help Joe R



I would expect most of your gain came from the cylinder heads. Those motors love compression. Velocity stocks would give you something that for all intense purposes is not measurable. More timing at idle will just make it not idle. A light flywheel would help if the motor was spinning 9000 RPM or something. The best mod to a 90 is adding compression. Or just put on the 115! These little motors would lose so much low end if you ported them up, they would not be worth anything on the boat. 




Please submit whatever questions you have to IHRTechTalk@yahoo.com.  All questions and answers selected will be displayed on this page as they come in.  Note: though all boaters are welcome, priority may be given to I.H.R. members.  Randy can not be held responsible for any advice given.  Though his information and expertise is second to none, he has no control over what you do with your boat.  It is up to you to boat safely and act responsibly, and his advice is only to be used as a guidance for your high performance boat/motor of which you are the one responsible for the risks involved.

Mark C.


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