Yamaha 70 performance upgrades needed from the Pro's

**Beachcomer** · 02-27-2013

Looking to get more from my stock Yamaha 70 TLRR which is on my Boston Whaler 15 ft Dauntless. I want to get to the beach 1st where as you guys want to get off the beach 1st. I'm and old racer that can't just leave things alone.

Model is "93" 70 TLRR that is pushing a 1000 lbs.
Upgrade to 90 hp carb's ? yes/no if yes is there a better vintage year
If i can use 90 hp carb's do i need an intake manifold also ?
If using 90 carb's what jetting would you start @500 ft sea level
Mill head ....what is min. cc ?
Reeds i will open up
Any mod's that can done to exhaust plate adapter?
I know there is high performance tuner but i don't know if this will work that well.
Looking for the spec sheet that is used for this engine if anybody has one.

Looking forward to all your ideas .

**88workcar** · 02-27-2013

All the basics work on this engine, compression, CCM reeds tell Chris I sent you, Do not mod the reed cage, just push the stops as far open as they will go. You may have to beat the assy back in with the butt of you hand. Do not buy a tuner. If you mod yours be very conservative. It will kill bottom end power and you need that on a 1000lb rig. If you port, I would recomend a minimal rise on the exhaust (once again 1k rig) maybe .040 up. You can widen and clean up the intakes. Yes on 90 carbs, I have some if you need them. I don't know if a light flywheel will help you. If you have a spare you may want to try that. Cut the rev limiter.

Keep in mind that a good prop and a great set-up will be your best investment, time and money wise. Good luck keep us posted.