I would like to know if anyone has had their 400 ported and still used the stock pipe. The reason I ask this is because I would like more power but don't want anymore noise and want all the bottom end and mid range I can get. The type of riding areas we ride here are steep rocky hills and I need to have a controlable linear powerband. I need good low end and not too high a clutch engagement. I have the head milled, vforce reeds, reed spacer and K&N filter along with airbox mods currently. I had the hotseat pipe and hated it. It was noisy even with the stoc muffler and there was absolutly no bottom end. The dealer tried to cure the no bottom end with raising the clutch engagement. It would be at half throttle before it would engage. Any help would be great.

 

Pipes are designed to make a certain HP at a given RPM. If you port your motor and it makes peak power past the point that the pipe rev's out at then you are wasting HP.

Don't ever let a dealer try to tune a modded Polaris. I only know of 2-3 nation wide that have a mechanic experienced enough to do it correctly. Your dealer obviously thought that a hard launch equaled bottom end, when in fact it is exactly the opposite. How in the world can you have bottom end if you are launching at 4000+RPM's? What you have is wheelspin, causing the rider to think they have a ton of useable low end torque.

You can have a motor/pipe combination that will produce low end power, and have it clutch to endage around 2500RPM's. Personally in the dunes I need the higher engagement, so I don't know exactly what spring/weight combo you would need. As for the Db issue HPD is the company offering a silencer that is below 95Db.

I suggest you call RCR or HPD and resolve the issue before this thread attracts contridicting and confusing posts. RCR's work woudld probably suit your taste for low end power bettter, as HPD is geared more towards top end power machines.

 

Thanks for the reply,

This dealer is actually usually pretty good but I think they were on crack the day they worked on mine. I expained the same thing to them. Higher engagement does not = low end power. I got them to refund me most of the money. You ought to try rock climbing with a purple primary spring. Not pretty. I talked to Rick earlier and as usuall he was very helpfull. He gave me a few recomendations that I plan on folowing. First I am going to work on proper clutching and see how a pipe works from there. I am still interested in the porting question with a stock pipe however for my old 350.

 

I ported my 300 Xpress with the stock pipe. I definately noticed a difference in power but it was mostly in the mid to top end. I of course, had to reclutch to take advantage of this new found power. Mostly I had to raise my engagement because of the way I ported it. I did raise my exhaust port just a little. In fact I didn't want to raise it at all but somehow I did. I had it engaging at 3000rpm and shiftout at 6000rpm. The only other things I did at the same time was shaved my head and honed out my carb for an extra mm.

Don't know exactly what kind of hp I got out of all this but It was well worth it. I would guess an extra 3 to 5 hp. Like I said thou, it was all in the mid to top end. Mostly because that was the way I wanted it to be ported.

If your looking for more bottom to mid power, I don't think porting should be one of your first mods. A "torquer" type pipe and some reed spacers with the proper clutching would be your best bet. You are allready half way there. Now, if you could only find a "torquer" pipe that was quiet enough for you.

 

Almost all the polaris pipes are "peaky" except the new ATV8 pipe from HPD. Even Polaris' engineers were thoroughly impressed with it's smoothness. I run the full race mod on the trail....take some guff for it, but love every minute that this thing is running. The grins for the buck factor are very well worth it.

Ken...and yes I've had all the other pipes to personally compare.