Top Speed with Yamaha Lower

[DoktorC]

How fast has anyone gone with a coned 3.1L lower?? I've recently switched from a 2.6 225 to a 3.1 250 and the 3.1 won't topend like the 2.6 did..I went from 6% slip to 18% with the same props!! I'm wondering if there is a big issue with that lower....

[thomast87]

I know yamaha hes three different gear ratio's. You might have to start with proping again.

[DoktorC]

I'm going from 1.86 to 1.75 which isn't really a big change. I'm going to try and HPDI case in the spring and see if there is any improvement. It's definitely an issue with the lower...the set up and props are the same I just added more power...

[native2]

I have been 102 with a 3.1 1.75 Yami case with a Bob's cone and torque tamer. Never worried about it...
http://i51.tinypic.com/x6hpk.jpg

[engineermike]

What kind of speeds are you running?

FYI I'm going 86-87 with an HPDI lower, though I know it's not the same.

[DoktorC]

Mine runs 92...no matter what. I tried a 28, 32, 34 cleaver and it always ran exactly the same...just the revs moved around. With the same setup I ran 93 with my 225 2.6...The 3.1 seems to have way more power just won't go...

I was having an issue with it blowing out (at 82mph) but I put a torque tamer on and that went away....something is goofy...