I have to agree with you cstark.The only thing changing is the rate at which air is entering and exiting.the volume is the same compresion is the same and so on. You can only gain so much with intake and exhaust mods, a 30% gain in horsepower over stock seems alittle unreal.If its true ct should design systems for cars.The biggest mod for a four stroke engine for power besides a bore and stroke increase is a cam change,this is the only real way to make a big enough change in the volumetric flow to make a big hp gain.Then your restricted to what the carb can flow.Cam,intake,and pipe should all go together with out the cam your still only packing the same amount of air into the same bore.Your just doin it a little faster.

 

Well I could be all wrong about this, maybe yamaha did find a way to design a engine with two carbs and 5 valves to perform respectivly with restrictive air intake and exhaust.Seems like it wouldnt be a very smart chance to take when there trying to be on top of the market.What a waste on research and development if this is the case. Id fire the guy who made this descision."Yes lets tone it down by 17 hp and give these people only part of what they are paying for, we will make them dig for the rest of the h.p. we packed into this high tech five valve state of the art engine."Plus this will reduce the lawsuits we have been receiving for the past 25 years with our other high output bikes and quads. Sounds like a good pitch to me. Please!

 

Hey guys, vever hear of a mistake. Me thinks perhaps Yammy goofed on the exhaust!! Have any of you heard about the 1997 & 1998 Ford Mustang Cobras. People were reporting enormous HP gains over stock simply by changing the mufflers, not even the entire cat back let alone headers, but simply the mufflers. It seems there was a serious bottleneck in the muffs. After enough outcry Ford actually issued a recall to change the mufflers!! This could be what is going on here. For sure after market tuners pad their numbers, wouldn't you. However, this entire scenario is in the realm of possiblity. I agree with the rag analogy of before. Anybody out there actually tried the new sytem yet!?!?

 

You are not comparing apples to apples here. You are talking about an 8 cylinder car engine vs a single cylinder atv engine. Big difference.

Changing an exhaust system on a V8 will increase results eight fold over what the "same" situation would do on a single cylinder.

On small motorcycle engines, not any ONE modification is going too bring big HP gains. But several mods can be used together too get the final results.

Someone stated that the 660R motor in the Raptor already was "highly" tuned and that uncorking the exhaust and intake would result in hugh gains. I have too disagree. The Yamaha 426 motor is "highly" tuned, and changing the exhaust sometimes hurts performance of the engine. This is not the case with the Raptor, and that's why I believe that the engine is not in a state of exact tuning.

Aftermarket exhaust will add HP too the Raptor, but not the 17HP gains that these companies are advertising.

 

I have a YZ426 and it puts out close to 50hp. It is a similar 5 valve design but only a single carb. It is a high compression engine, and of all the exhaust shootouts, the stock exhaust still puts out the most HP. The others distribute it over the RPM range, but none make more HP. This is typical of a 250 class dirt bike as the 250 and 125 class machines are sooo competitive. Their stock machines are compared in dozens of magazines and those reviews and race outcomes weigh heavily on their sales.

A close friend of mine was talking with a Yamaha R&D guy and got the scoop on the Raptor. It has been in the works for 3 years. When the 400EX came out, they redesigned it, as the 400EX was a better machine and handled great. They had it redesigned, and then the DS came out with tons of power. Again, they redesigned. Now they have a machine which will hang with both a DS and a 400 in each of their environments in stock trim.

The motor is very detuned. That 426 puts out 47-49 hp in stock trim. The 660 around 38. There are many posts from Scooby who found that European site about a street/race bike with a version of the 660 in it. They get ton's of power from that motor. Why would anyone doubt the ability of that motor to make incredible power? (I realize that bike has internal motor work, and not just exhaust, so not all of the power is attributed to the exhaust)

Would Yamaha detune their motor with intake or exhaust? Absolutely. The machine already does 75 MPH. Who wants it to do 110? They just need it to hang with a DS, and handle like a 400, and don't cause the beginning of another consent decree. Sounds like bang on to me..... If the aftermarket guys hop it up and someone gets killed, it doesn't go back to Yamaha. Another point here is that there isn't another machine like it. Not like the dirt bike classes. If honda came out with a 650EX then there would be some competition in the class. (Ever wonder why Honda hasn't release their next sport quad. It could be the exact same strategy Yamaha employed to 'shock the performance nuts' with their Raptor. They could be testing a new prototype right now, side by side with a Raptor and DS.)

I would definately expect some big things with the raptor motor. Exhaust is just the beginning.

I can't wait to get mine. My 400EX is a great machine and I still enjoy riding it. It has become tougher to not want more power, after getting of the YZ. I hope the Raptor will help me with this.

I still love Honda for the reliability, but Yamaha has really earned my respect for technology with my YZ. I can't wait to get on the Raptor for the winter. Studded tires, wheelies across the lake.... OK, got to stop typing....

RM

 

Anyone notice that it is mostly Ds650 riders that are "crying". There bike can barely hang with the Raptor in stock form, now they are gonna really get destroyed.

 

Right on! And I have also noticed that the dealers around here are willing to sell a ds for the bottom line. Below retail. There are 2 of them for sale in the cycle trader near me with low hours for $5700 and they have been for sale for awhile now. Why does everyone think that these power gains are not possible? The answer is easy some are jealous, some (most of us) have never watched anyone modify an engine of this stature.. Lets admit it prior to the ds and raptor a 650-660 sized quad was a fairy tale or a special test in dirt wheels and no one ever rode or modded it right?

so those who say its wrong and can't be done
you all know because you tried right?

 

Guess what people? that engine makes 50HP in plain form in the bikes in europe. This is a competitive street bike we are talking about. The bikes stock run 110mph. We have no difference in the engine other than the intake and exhaust with a different cam timing. so how do you get the same 50HP ? change the intake and exhaust. There are a crapload of european and japanese sites tuning these motors. They make 60HP fairly easily and mod up above 70HP believe that!

 

OK, your right, Iam jealous. I should have known better to read your yamaha forum.Id say the same thing about my ds thats why there are packages out there for the bike.Oh and by the way iam not crying iam just bored as hell so I read these stupid forums.But ill stay away from your yamaha forum so you guys dont get all defensive and read one persons point of veiw and take it to heart.Thats just my opinion you know opinions are like a$$holes everybodys got em. Not that i know anything about engines anyways!But ds raptor blaster 400ex or banshee I feel the same way. 17 h.p. is alot

 

Why dont you compare displacement of a 5valve per cylinder ferrari to a 4 valve cadillac with a 32valve v8, similar displacement, but you know which one has open intakes, exhuast, and the extra valve. Right?