XR600 Before and After. Supertrapp to FMF Powercore 4

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OMG!:) How could I have been so naive as to think I was getting good power out of that old PC/Supertrapp POS!

This thing is a new bike with this pipe. I can't believe how much better it runs (and sounds) with the Powercore 4. Huge increase in smoothness, roll on power, and rev capability.

For those interested FMF's recommended jetting for sea level 70 degrees is:

155-158 main

65-68 pilot

Needle in the fourth position from the top.

My settings are:

10.5/1 Wiseco piston

160 main

68 pilot

I was running the needle in #3 position, now it's #4 and I think this was a major factor in the performance increase aside from the pipe. Roll on pull greatly increased.

For those not too concerned about sound levels this pipe is a "10" for fit, finish and performance.:smirk:

Is that the stock header? Have you ground down the welds?

Yeah. Stock header, ground welds...

Nice looking bike :smirk:

nice clean lookin SixHundo !! how many disc's were you running in the supertrapp?

I've been looking for a new exhaust to replace my old supertrapp on my 89. I've been looking at the powercore 4, but everwhere I have seen them for sale state they will only fit 85-88, 91-98, 00. Though the FMF website says the exact same model number will fit years 85-2000. I guess a phone call to FMF should clear this up.

Anyone try to fit a powercore 4 model 041022 on an 89 with the stock stainless header pipe?

You're going to be hard pressed to find anyone who makes a twin pipe muffler to fit the '89. Supertrapp was the only one I knew of. You'll most likely have to get a full system. But not to worry. It's not that the supertrapp doesn't or can't make good power. I was very happy with the system on some of my other XR's including an '89 600 and a 650R.

The main problem with the pipe on my current bike was the packing was shot and it really killed the power. With nice tight packing and 8-10 discs the supertrapp makes excellent low to mid power. Any more and it just starts getting heavy and loud without much benefit.

But... I am without a doubt a convert to the FMF PC4. It's lighter, looks better, runs better and sounds better.

Clean 96' but how can you live with those purple side covers and fork boots. Those things were some of the first to go on my 96' :smirk:

I've just bought a XR from 86 with supertrapp headers and FMF muffler:

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Mine is mounted a lot differently though..

I did recently re-pack the muffler and remove all the carbon form every little hole. I'm running 12 discs in it right now. That's just how it came on the bike. The exhuast isn't so bad, but a bit loud. How does the PC4 compare in sound? I really like the modern look of the PC4, but don't think I could justify the cost of a whole new system.

Clean 96' but how can you live with those purple side covers and fork boots. Those things were some of the first to go on my 96' :ride:

I dig. I must admit I ask myself how I live with the purple. That's what made it so easy to hack off half of the side panels in the first place.

The fork boots are history the next time I feel like removing the forks for some reason...come to think of it I could just cut them off...:smirk::)

I did recently re-pack the muffler and remove all the carbon form every little hole. I'm running 12 discs in it right now. That's just how it came on the bike. The exhuast isn't so bad, but a bit loud. How does the PC4 compare in sound? I really like the modern look of the PC4, but don't think I could justify the cost of a whole new system.

It's loud. As loud as a 12 disk supertrapp but a deeper "mellower" tone. Not that anyone annoyed by noise would care to appreciate the difference.

It changes the character of the power, and the resonance of the power pulses. It makes the power delivery smoother by removing the brick wall at the end of the pipe. I used to think that wall actually helped the power and it does but in a very narrow band (low end). Now the bike will pull the front end up as it revs whereas before if I wanted to wheelie I had to make sure I was real far down in the power and let the torque do it because it would fall off at the top.

Keep in mind all of this is on the street with street tires. Off road you wouldn't be able to appreciate the subtleties of the power delivery I'm refering to because of wheelspin/lack of traction, etc. I'm also using good 100 octane fuel mixed 50/50, without which power quality would also be adversely affected.

mars volta bike das nederlander

If you are using that grumpy Kehien , runs way lean, run it as rich as ya can, especially with a pipe setup, even just uncorking it, slip on, all the better. Mod the airbox too, just go heavy on the fuel supply.

I'm runnin the Supertrapp racing exhaust on my 650L. I run 16 discs. No, I didnt notice a increase in power from 12-16 discs, but I love that Harley-esque exhaust crack when I rack the throttle. Of course, I wear ear plugs while doing any long distanse riding, so the loud pipe doesnt bother me. Loud pipes save lives.

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