His quad is just stronger from the factory than mine is. I can jump on his quad and run 1mph faster, and he can jump on mine and run 1 mph slower

 

I have the Pro Design Filter with the lid off, Big Gun full exhaust, 165, 170 and 27.5 pilots.14 tooth front sprocket.Now it runs 82.3 mph at 14.26. My friend has the exact same mods and his runs 83.3 at 14.19.

 

No2Stroke,

What is your needle position and how far out have you turned the air screws? You sound like you have a nice setup.. maybe one worth replicating.

Do you have any idea what kind of speed you could expect from all of the same mods, but with the stock pipe with the baffle pulled?

Thanks again!

 

I believe that would be a 4th gear dyno pull which is what almost all dyno operators use to get hp. figures. I used this formula and came up with this.

336 X Rear gear ratio X MPH
______________________________= RPM

Tire diameter

Rear gear ratio is figured by taking 4th gear ratio which is 1.047 X the Secondary reduction ratio which is 3.076 X the Primary reduction ratio which is 2.088. This puts the overall gear ratio at 6.72.

336 X 6.72 X 53
_______________ = 5983RPM
20"

6000RPM is where peak hp. has been shown to be so this would put it about right for the figures you've shown.

Using the same formula for the 77.8mph would put this at 8783.3RPM or right before the rev limiter which is where most dyno operators rev the engine to, which would account for the low hp. figure since the engine doesnt make much power beyond the 6000rpm mark.

Top speed cant be accurately measured on the dyno since it is at the rev-limiter and most bikes cant pull to the rev-limiter in the a "real" world situation.(In the upper gears of course)

If it was a 5th gear run that would put peak hp. at around 5100rpm and I think peak hp. occurs a little higher than that. Check with the dyno operator next time you see him and see if this is correct. I would like to know.

 

Digs thoughs are the exact equations in the manual that came with the dyno at my dealer.
I looked it over once and was amazed by all the mathamatics it takes to operate a dyno.
Great Post!!!

2000 SCRAMBLER 400 2X4

SCRAMDADDY400

 

Oops. Guess I should have clarified my question.
I knew the equations were correct. I just wanted to know for sure if this was a 4th gear dyno pull.
Thanks

 

Sorry Digs I thought you were referring to the equations.hehe.

But yes you are correct the peak rpm and horsepower are measured at 4th gear.
When my dealer measures top speed thats when 5th or 6th gear come in play, usually horsepower drops considerably. There has been a case were a modded banshee pulled horsepower up in five gear but dropped shortly after it revved out.

Note the raptor reading I gave, at the top speed the horsepower rating was reduced from "38" to 18.

2000 SCRAMBLER 400 2X4

SCRAMDADDY400

 

I have yet to mess with my needle or air screw or clip position.I may need to fool with it a little, but it seems to be running pretty well.Id hate to dig into those 2 carbs again just to make it run worse

Its kinda hard to say what your Bike will run with the stock pipe because the addition of a aftermarket pipe would require bigger jets, however if you have a good intake system on it and a free flowing air filter i dont see why it shouldnt run close to 79 or so.On another level, i installed a 14 tooth sprocket when it was bone stock and it slowed down, but after the Pipe, jetting, and air filter, it pulls it really good, besides, it is hard to keep the front down with the 13 tooth and a aftermarket pipe.