Depends...

If the power curve is fairly flat from 7000 rpm on, then lowering the front sproket will probably give you better low end and still keep the 74 mph top speed.

If the power curve drops off sharply after 7000 rpm, then the top speed will decrease.

As soon as someone dyno's one of these a lot of the questions can be answered.

 

hi all

i found half the problem.1/3 of the intake extension on the airbox lid is blocked off.
i took the extension piece off and it made a big improvement.
there is no tors system and no electrical wires on the carbs.
the throttle has a set screw but it is set to max.

what else should i check , my bike is next to me.

paul

 

A idea just came to me..... my friend just bought a xr650r.... when he bought it he discovered that honda had restricted the intake boot ( between the carb, and motor ) had a restricted down about 2/3...... it had a rubber "block plate" that had a rectangular opening to it..... he cut it out, and rejetted... man what a diff.... I wonder if yamaha may have done something simular????

Just a thought

 

What part did you take off? What exactly did it improve? Did you check the carbs? Are they opening up all the way? Keep the info coming i will make all the adjustments everyone posts to my raptor when i go home friday night. This weekend will be great for riding forecast says temps in the low 60's here in indiana

Later

 

I'm not a mechanic, but will an Engineer do?

I am assuming you are getting your RPM numbers based on math involving the gear ratios. How about getting a tachometer, putting the rear end up on a jackstand, getting the bike in 4th or 5th gear and see how high of a tach reading you get. Without a load, and without some sort of limiter, you should be able to get the full 9000rpm.

Although you mentioned that going downhill only improved the top speed by 0.1 tenth, remember that at those speeds, aerodynamics has a lot to with how fast you can go. The difference between the aero drag at 74 and the effects of gravity going downhill probably don't give you much help in top speed. You are only talking about a 400 pound machine, not a 10 ton semi.

I would try the tach approach if you really want to find your answer.

 

Yes, I'm planning on it. I posted this yesterday in this thread at 4:38pm...

"I'll soon post the max speed for each gear, the corresponding rpm, and even the top rpm of 4th and 5th gear with the wheels off the ground. For the last one I'll of course have to hook up a tach but that should be easy enough."

 

the raptor airbox intake is the same as the banshee and the blaster , the intake turn up under the tank. the turned up section can be removed from the lid.yamaha has resticted the lid in between the lid and the "snorkel pipe - thats what we call it".the restriction is a soft piece of rubber that is part of the moulding prosses.
i have just cut it out with a knife and fitted the "snorkel" pipe back on to the lid.
the snorkel pipe opening on the raptor is the same size as the lid opening , there for not a restriction as on the banshee and the blaster.

the motor is more responsive and rev high in 4th and 5th gear.

you can't take the snorkel pipe off completely because the engine breather pipe fits into the snorkel.

paul

 

Why dont some of you go up on the sproket and see If it will pull with out losing that much low end? other than in sand, where you go down to gain the lowend power robbed by sand, each tooth on the front will net you 2-3 mph top end if you can even begin to pull that high a gear then dont worry about it. You will be able to with a hi flow filter and optimised jetting and a white brothers E series pipe for sure. This may help some people in the long run by getting rid of the instant wheelie you get trying to gate this thing hard on a drag race.

 

I bet this has a LOT to do with limiting the power. Has anyone else tryed this? I also was going to take off the snorkel, just there's the breather line. You could probably route it directly into the lid or the airbox itself... but that a little down the road.