Four stroke performance upgrades?

[sweden]

Not quite so fast!! Depending on your dollar's. You may want to consider a Wipple blower. Their was a thread with a guy from Europe that was running a Honda 225 with a Wipple Blower at over 100 MPH. I believe it was titled "how fast is your four stroke". The unit would be much easier to mount on a Honda or Suzuki, though. A set of J&E pistons would be sweet. And a high lift cam would be the iceing on the cake. Their are some limit's on RPM starting with the limiter. Then, and more important is the fact that Yamaha and Suzuki have shim's on top of the valve bucket where as Honda does not. Yamaha has changed this on the 4.2 unit's, but all 3.3 unit's produced today still have shim's on top of the bucket, and cannot take high RPM. Thank's Martin

I run 104 mph whide à stock Honda 225 i have not try the charger on the boat get only on dyno

[whipper]

I run 104 mph whide à stock Honda 225 i have not try the charger on the boat get only on dyno

Sweden I remember that video of you running 100+ with that honda very impressive!!

[gsmarine239]

How light can you make a Honda 250 and what rpm do ya think it could spin at what hp?

The RPM and hp are limited by the ECU. Simon marine and turmax are working on reflashing the ecu to allow the map sensor to read boost and gain a higher RPM. Once this achieved there are rotating assemblies and valve trains that can exceed 10,000 rpm available. With a stock ecu high flow heads, intake, and exhaust will provide some hp increase. I haven't tried to lighten a honda 250 but a honda 150 has a block hp potental of 300hp naturaly asperated and 800hp boosted.

[Lockjaw]

300XS or 250 HO.

Get the 200 SHO and have hydrotec mod the ECU. I believe the way Yamaha controls the HP output is by not opening the throttle all the way.

[Lockjaw]

The RPM and hp are limited by the ECU. Simon marine and turmax are working on reflashing the ecu to allow the map sensor to read boost and gain a higher RPM. Once this achieved there are rotating assemblies and valve trains that can exceed 10,000 rpm available. With a stock ecu high flow heads, intake, and exhaust will provide some hp increase. I haven't tried to lighten a honda 250 but a honda 150 has a block hp potental of 300hp naturaly asperated and 800hp boosted.

OK my question there is this. If you don't boost it, and you do say, port the head(s) and add a bigger cam, then you have to be able to get the thing to have enough torque to get out of the hole.

[whipper]

Is the honda VTech the same motor in the cars or bikes? I would think the torque isn't a real issue with Hondas as Sweden can turn a 36 inch 15+dia Herring propeller to the limiter at over 6000 rpm stock on a 24fter!! I know guys are having a hard time reaching the limitter with 30pitch props with the 250SHO and XS

[whipper]

Why cant the SHO turn 8000 rpm and have over 400HP in the outboard? They are running these in there Waverunners. The FZR Riva E1 has a 8300 rpm limitter and puts out 400+hp. I thought this was the same motor as the SHO? The FZR is the Yamaha SHO water carft. Anyone know why this cant be done to the outboards also. Hears a clip of the SHO with 400hp and watch the RPM go to 8000. His jetpump cant handle the torque and he says he needs to upgrade that to handle the power better. I might give Riva a call and find out if this is the same block as the outboards. http://www.youtube.com/watch?v=mZWp8qZ3WWU

[whipper]

Hmmm Called riva Racing and the 400 hp 8500 rpm limited FZR watercraft uses a 1.8lt inline 4 not the V6 SHO. He said the motor goes 0-80mph in 2.5sec!!! The only designation of similarities is the SHO. The motor is actually Motorcycle based hence the FZR designation. Man why cant the outboard division get there poop together and do this with there outboards. http://www.diyfactory.org/oLF7bHoWQ0...tTest-com.html

Dyno run to 400hp.http://www.youtube.com/watch?v=mAgYMWCS4kU Engine is torboed and very very light.

[Turborr]

If you tamper with a 4 stroke outboard to increase performance....better have your sea tow or equivalent up to date.

[whipper]

If you tamper with a 4 stroke outboard to increase performance....better have your sea tow or equivalent up to date.

Be cool to make an outboard using this engine though that they use in the watercraft. 400+hp and they race with them in offshore events and prove very reliable. Either that or would make a pretty light power to weight surface drive setup on a 21ft or less hull.

[VectorPat]

Did you see the torque on the dyno run? it would never get a normal production hull on plane.

[mackeral5]

Do the current models still run a gearbox? Previous fx yammies had a gear reduction unit to lower pump rpms and boost low end torque, motors turned 10k+...

[R.grover]

that's the thing the two strokes do have better torque. with the 225hp Honda doing 104mph what hull and to me the math don't work to do it.

[sweden]

the hull i use twister 24ft weight 1150 kg empty whide engine
on shoot out i come up to 103,4 mph on mile course
just look it up on youtube if u dont belive it
i have tha same speed in it that tha same boat that race i u i m class c that use mercury 200 Xs

[CDave]

Why not adapt an aftermarket computer sys. like from Holley, FAST or Accel? If the engines are variable timed cams you could always "lock out" the cam movement to eliminate any problems with that and aftermarket ECU's.