I had read that the original engine was putting out 250-260HP.

Supposedly this was too much for us unwashed masses, although I believe you can never have too much power! The order allegedly went out to the engineers, calm this puppy down!

If this is true what was done to de-tune the bike, and is it easily restored?

Just imagine what Jay Gleason could do with 25% more power!

Actually I read somewhere that it made 337HP at the crankshaft & was 1900 cc.

The problem was getting the bike to hook up in any gear..

What I've read was that the original design was set to 290hp.
The problem was that there was no tyre which stayed on at this kind of power.
They then downtuned the bike by steps whereas the tyre was allways the issue. All the time they were acompanied by Bridgestone to design the right tyre.
We know how the story ends

Then I heard from my dealer that they actually didn't change anything to the engine itself to downtune it to its current performance. They used all kind of tricks like air filter, exhaust, fuelmapping, etc...
Using this information would mean that if we reverse the downtuning by changing the components, we could get it back to 'original' performance. But beware, you won't find a tyre which will stay on the bike....


*- DiMMaX out -*

The engine displacemeent was reduced, and the compression lowered. Then the other things combined to make it 197HP. (an acceptable, marketable figure)

Would be cool to know what this 1679cc motor truly put out when they first built it, before the detune and whatnot.

Based on the dyno figures we are getting it looks like the 1700cc VMax engine is capable of putting out some 225-235 hps at the crank without internal engine modifications.

How do we arrive at that number?

The stokc bike with 197.5 hps at the crank makes about 172-173 rwhps. That's a 13% loss from transmission, gearing and shaft drive (BTW: not bad at all)

With the latest configurations pushing north of 190 SAE rwhps (custom intakes, custom exhausts, custom fuel maps), that's equal to about 218 hps at the crank give the 13% of losses.

Right now we see our way to 195-198 rwhps, maybe more with a full race exhaust system, custom ignition maps and all the other goodies available...

fxstein

I've heard that it was originally 289hp and it had to be detuned as it blew up the diff with that amount of power , not to mention the safety and marketing side of things.

Cheers vmaxr

There wasn't any problems with drive train reported, just traction problems.
Here's the original 337HP fire breathing monster. Yamaha detuned it and left out the variable valve timing feature, fearing it to be too much for the street.

"The cams of the new Otodama engine are chain driven. A control chain drives the intake cams of each cylinder bank and the exhaust cams are gear driven from the intake cams. Its pretty much a typical overhead dual cam design with a little twist. The gears that drive the cams can rotate by 20 degrees and are controlled by internal oil channels. Oil pressure sent to either side of the gears, advances or retards cam timing by the same 20 degrees.
It is pretty much an on/off design, similar to the good old vboost that used to kick in at 6000 rpm. Just like the prior generation vboost this 20 degree advance of the cams will switch at a certain rpm and will put the engine into high rev/high power mode. The advantage over much more complicated variable valve timing systems like the ones in cars is that it is much simpler, less parts that can fail and a lot lighter.
It only takes two additional oil channels and a solenoid on top of each cylinder bank to control. It also makes it a lot easier to control for a rather small and lightweight ECU as part of the bikes design.
This engine will make the Next Generation Yamaha Star Vmax (2008/2009) most likely the fastest production street bike ever built."