Backgound:
Stock 2000 Scrambler 400 4X4
5'9" 230 lbs
I like all kinds of riding but prefer fast trails and hill climbing

I currently can not get over 53 MPH (By GPS) and bike seems to be reving very high but not going as fast as it should.

What would be best and why........

RCR Stage 1 Kit (Midrange Pipe)

OR

HDP trail pipe with Agressive Clutch kit

I am leaning toward the HPD solution with the RCR air box mod with re-jetting. Would I need a silencer or muffler with the HPD pipe or could I use the stock muffler? Does the RCR air box mod include a Uni Filter and if so do you clean and reuse them or do they need to be replaced? How would I determine the jetting requirements of the mixed solution? What would be the best clutch arrangement for my bike / size / riding ?

Any help or suggestions would be greatly appreciated.

TIA
KD

 

I have the same quad with the HPD trail pipe and agressive clutch kit(without the new helix), Uni filter(washable), homemade airbox mod, V-Force reed valves and most importantly an Aaen roller clutch. It was amazing before the roller and even better now.

I am very pleased with the HPD set-up. It rips and they give you the jetting specifications to get it just right. I kept my stock silencer to keep the noise down.

Brian

 

Your stock silencer will fit an HPD pipe from what I've been told. With the RcR air-box mod, you do get a Uni-Filter. They can be washed and used over and over again, I can't count the times I've washed mine, I use 100% mineral spirits, and it has no ill effects on the seam glue. I would also suggest getting one of the HPD clutch kits. Rick at RcR also sells HPD components, he could give you more info on the best clutch kit for your needs.

 

With the HPD trail pipe, trail porting, HPD agressive springs/wieghts, HPD billet head, AAEN's roller, 38 TMX, K&N conical (no air box), and 14/34 gearing I hit 73.9 MPH on a GPS. With 13/36 gearing (stock) I hit 67.3 MPH on the GPS. This is at about 6800 RPM's at less than a 1/4 mile. With the 14/34 sprockets I didn't have to buy a new chain. The range of adjust made up for the sprocket sizes.

 

KevL

Your speed obviously went up considerably with the 14/34 sprocket setup. What are the ill-effects of the setup? Acceleration? Low end?

Thanks (would this effect the 4x4 system?)

 

I just ordered the stage one kit from Rick at RCR,
and I went with the HPD pipe because the stock (forest approved) muffler will work with the HPD pipe, but not the RCR pipe. The RCR air box mod kit comes with the Uni filter, a new rubber grommett for the additional breather hole you drill in the front of the air box, and instructions for drilling more additional breather holes inside the box. Be warned, after I drilled the additional holes inside, the Scrambler seems louder to the rider because you can hear much more engine noise coming through the new air box holes. The uni filter is the foam type that you buy air filter oil for. It is cleanable and reusable. The stage one kit also comes with a jetting chart, and several main jets and a pilot jet that Rick at RCR thinks will be close for the information you gave him regarding altitude, temperature, and type of riding you do. You will need to change the jets for sure because of the additional flow your engine will have from the mods. The new pipe and air mods (either/and/or both) require jetting changes. When the air box is off, removing the carb to change the jets is pretty easy. I went with the HPD "plain" clutch spring, which is between the stock Scrambler "white" spring, and the aggressive "green" spring. This spring seems to be a good compromise that doesn't cost you too much low speed control, but still raises the engagement RPM. You don't don't quite need to use the reverse over ride button to back up, but almost. I took the Scrambler out to test this all out, but when the temperature dropped to 23 degrees, and the blizzard started, I headed back to the truck. I decided to have the local racing mechanic that works on my dirt bikes do the jetting so that I could be sure it was perfect.

Good luck,
Lorrin Lee
(99 Scrambler 400)

 

Hey Kevin,

I have a '97 Scrambler 400 and did some speed tests against a police radar trailer and the speedo in my truck when I first got it. The speeds were both within 2 mph of each other and came to about 60-62 mph topped out. I'd say there is probably some error in the the gps reading because of some of the other posts I've read regarding the speed given by them. My buddies Timberwolf will do 50, for example, and I left (when my Scrambler was still stock) him sitting like he's sitting still, literally.

As for the pipe and clutch choice, I opted for the RCR set up. Love it!! The difference is like night and day. It's almost like putting a different motor in the thing. The only gripe is the installation. Mine went in very tight. Not much room for working in at all. You also have to cut a pretty good peice out of your pipe heat guard, but you can't even see it after putting it back on. Other than that, I love the power gain. I raced a guy at our riding spot who had a DG pipe on his and beat him by about 2 or 3 quad lengths through about a 1/4 mile distance. Repeatedly. I'd say the RCR mid pipe gave me at least 10mph on the top end. Just a guess. I haven't seen that police radar trailer in my neck of the woods since the pipe went on and I'm not letting anyone drive my truck fast enough down a dirt road to keep up. Haven't gotten any volunteer's to use their own rig either. Soo, that's my guess.

I'm about to go with a larger carb and different reeds because no matter what the guys out there tell you, a pipe is not the only answer we need for beating banshee's. I can kill them off the line for about 100' but once they hit 4th it's all over but the cryin'. By the end of a 1/4 mile run they get me for about 4 quad lengths. The cool thing is that I can maintain that kind of a run in 4 or 2 wheel drive. What other 4wheel drive quad can do that!!! Gotta look on the bright side of it some how .

I need to know whether or not I have to stay with the same tire sizes that come stock in oreder to keep the 4wheel drive working right. I've heard you have to keep the size ratio the same but does it affect the 4 wheel drive engagement if the front and rear tires are smaller than stock? Any help would be appreciated.

Dane Sharpe
'97 Scrambler w/RCR mods and split brakes.

P.S. Rick at RCR was alot of help. I would highly recommend consulting him. Very good customer service.

 

Simple solution: Call Rick @ RCR and have him put you together a Stage 1 Kit with a HPD pipe in it. With the HPD Pipe, you can use the stock Silencer / Spark Arrestor, or use an aftermarket silencer. The HPD pipe fits a bit better than Rick's ( I've owned both ) and the performace is equal.

 

There was no affect on low end. It will still pop straight up with any traction. I only use the 4WD when I have to. I didn't notice any difference. As far as the GPS accuracy goes, if you are getting a good signal they are pretty accurate. I have checked it against 3 different vehicle speedo's. Yes, vehicle speedo's can be off a little, but unless you can get a radar gun a GPS is the next best thing.

 

Thanks everyone.

I ordered the HPD trail pipe with muffler. Also ordered the aggressive clutch kit with roller. I will modify the air box and replace the steering post and rejet. Guess what I will be doing this Thanksgiving Weekend.

Again thank you for all of your input.

KD