640 Engine Height

[Mike Nelson]

Hi all, What hole is everyone running on there engine on? And what prop.



I am running middle hole on my 90 opti, with a 20p laser 2, should i jack it up another hole? and get another prop? 20p seems to over rev my engine way to easy.



Also what have people done to improve there holeshot in the 640s they seem a bit slow when loaded.

 

[byron cooley]

I have an 05' 640LX with a slightly tweaked 75+ Opti. I have tried many different props and engine positions since new. Here is where I ended up.

Motor height - 1 hole from max

20" Laser II with medium plugs, all over the 5850rpm limiter at 3/4 throttle, 48.6gps just as the ECU pulls the power back with a balistic holeshot.

22" Laser II with large plugs, 5730rpm @ 51.2gps with decent holeshot

These are with myself, gas, and tons of tackle. I tried the motor all the way up and the handling suffered.

 

[Mike Nelson]

Hey, byron thanx for that info. How do you find your holeshot with 2 people and full well? I find mine slow but does not feel BAD but i certainly love how it jumps up with just me and an empty well. What would be the best prop for my setup you think, some others on here are running 21p 4 blades.



When you say tweaked 75, what have you done?

 

[Gilbert Scales2]

I have a 640TF . I have a 6" jackplate, 22 pitch laser II prop, and a 2002 90hp Merc. Light boat GPS 48.7 MPH. Loaded 45.9 to 46.5. The only way it goes 50MPH is when I am towing it. Boat is in perfect condition, and I have lots of friends with 16' boats of other brands with the close to the same results. I spent a bunch of money trying to get 50MPH with many good mechanics. and havn't done it. The hole shot if fine.

Byron, please let us know what you did to the 75. I have 15 extra hp and cannot achieve that.



Bubby

 

[byron cooley]

The first and best thing is the lake I fish most is only 800' above sea level. I have changed the throttle body and some re-mapping of the ECU. Also the Opti's have a higher limiter (5850) than the "Classic" motors (5250). Real soon My ECU is going to Simon Motorsports to get re-done. They told me for $500.00 It will become close to 120hp with a 6200rpm limiter. Remove the throttle restrictor and send them the ECU, they flash it and send it back with a 1 day turn around. Not sure what you can do with the classic 2 stroke motor.

As far as the holeshot with 2 people and full well - about 6-8 seconds with the 20" and 10-12 seconds with the 22". After the next tweaking I might need a 24".

 

[TOMMY RICH]

90 Classic is 5500 RPM