I am looking at buying a boat that has a 40 HP Yamaha 2002 model motor on it and the owner says he runs 100-1 fuel mixture is this right ? checked the net and very confusing all different stories of what to run ie 50-1 , 75-1 any experience out there of guys that have same motor It has done 120 hours

My 2015 Yamaha 15 ran 100:1. I used Yamaha 2t oil. Never had an issue.

If you're concerned call yamaha marine.

big heaps thanks

yamaha 2 stoke's run 100:1
have to use genuine oil though.

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dave.h said..
yamaha 2 stoke's run 100:1
have to use genuine oil though.

I think that only applies to the three cylinder version though..

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jbshack said..

dave.h said..
yamaha 2 stoke's run 100:1
have to use genuine oil though.

I think that only applies to the three cylinder version though..

correct, and the 2 cyl motors but dont know about the larger older 100+ hp

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dave.h said..

jbshack said..

dave.h said..
yamaha 2 stoke's run 100:1
have to use genuine oil though.

I think that only applies to the three cylinder version though..

correct, and the 2 cyl motors but dont know about the larger older 100+ hp

Actually what i meant was the 2 cylinder 40 Yamaha (CV) is 50:1 still. The 3 cylinder is the only model and below, that is 100:1

I've got a 2006 40 Yamaha, self mixes oil, oil reservoir under motor cowling