Rick Ritter and ChopperBill, from the post bearing their name, are concluding from info given to us by our very own forum member"425Expedition" that we can use those H.O. components that make a Scrambler and a
H.O. Sportsman on a 425 EXP!! Matching part numbers on the Camshafts between a stock Sportsman and a 425EXP! Way Cool!! Maybe a 38mm carb instead of a 40mm, its' a lot cheaper too. Now find one of those Cams! Backordered till January 'cause of all the guys who want to upgrade their Sportsmans. Now add the guys who want to pump up their 425EXP's. And add that AAEN megaphone muffler while we are at it. This is a great upgrade for the 425EXP. I know what will be under the X-mas tree for my son's Expedition. I wonder which intake manifold would work best?
Silly Later,,,,,Fourlix

SP500 H.O. as of Friday,Oct 20
EXP425- H.O. by New Years!
Everything fits on my Trailer again!!

 

We have come a long way from G.I. Joe action figures... to exhaust pipes under the x-mas tree!

 

I just went out and took the sidepanels off of my 2000 Sportsman 500 and my son's 425 Exp.
The cylinders and cylinder heads on these two machines are visually identical. It is the same engine, in very different configurations. Since the part numbers for the camshafts are the same, the hotter cam from the Scrambler 500 and the H.O.
Sportsman is definetly going to work,,,I think.
Silly Later, Fourlix
Now where did 425Expedition get those part numbers
from the Polaris Web Site?

 

now i'm kinda numb, but couldn't you just take a 500 rod and piston and turn the 425 into one, since everythings the same, or is the crankshaft stroke different, or something. I'm bound and determined to try the 300 jug on a 250 to see what happens....

 

The crankcase is totally different. The crankshaft could be too. But the cylinder and piston from a 500 could be an instant "Big Bore Kit" for the 425...460? Big bore/short stroke could rip! What's the stroke of the two machines? So what's the difference between the new 425 Sportsman and the 500? Not much I bet, just bore and stroke, carb, valves maybe? If somebody wanted a 425EXP with a 500 H.O. motor I bet they could do it. But we are definetly talkin' crankshaft work...I think.
Silly Later,,,,Fourlix
SP500HO
4??EXPHO

 

fourlix,

I run the Supertrapp IDS-2 pipe on my bike. The Aeen pipe is alot louder and you can get the same power out of the Supertrapp. The intake off the Scrambler should work with 40mm carb. The parts manuals are in the trail tips section on the Polaris website. I am not sure about putting the HO cam in the Xpedition. I need to find out at what RPM the clutches engage on a Scrambler. The cam may not make enough bottom end torque to work right with the five speed tranny. The clutches can be manipulated on a belt drive bike. I do not think that there is an easy way to change the engagement RPM on the five speed.
I am going to be trying an experiment on my bike. Need to make the bike turn 28's over easily. If it works I will let everyone know how to build a mega-torque motor for there Xpedition.
There just is not enough people that mess with the old 425 Magnum motor and no one I know of is messing with the 425 Xpedition motor.

fasternu,

The rod out of a 500 will not fit. The stroke is longer on the 500.

 

What an ingenious idea. Never thought of that. I wonder how a 400 HO Sportsman would handle? You know, with the 500 jug, bigger carb, & HO cam. If the 425 truly is a shorter stroke, I bet it would really rev. Might make the loss of the 2 stroke (in a couple years) easier to tolerate. That seems to be the weakness of my brother in laws non HO 500, it doesn't rev worth a hoot. I know it doesn't make sense to make a 425 HO when you can get the 500 HO, but for the guy that gets one & wants a little more zip & doesn't want to take it in the shorts in trade.
Let us know how it works out, this shows much promise.

 

Farmr123,

From what I have heard the motor in the 400 Sportsman is a tweaked 425 Magnum motor. But I cannot find out yet. The parts manuals are not available yet for the 2001 models yet.

 

Thanks for the info "Expedition425" you were right. The Polaris Web Site "Trail Tips" does contain parts manuals!! So the cylinder head on the 425EXP and the 500 Sportsman and the 500 Scrambler are all THE SAME!! Part # 3085527. The cam in the 500 Sportsman and the 425 Expedition are the SAME!! Part # 3086212. Sportsman and Scrambler cylinders the same. Part #3086811. But did you know that the piston, rod and crankshaft are different between the Sportsman and the Scrambler? That means a Sportsman with a Scrambler cam and carb is not quite an H.O. perhaps a lower compression ratio? I found three different intake manifold part #'s, three different pistons, rods, cranks.
But the heads and cams do match up. That is not just the castings but with the same part #'s that means they have the same machining and specifications and that they are INTERCHANGEBLE!!
YOOO-HOOO Silly Later,,,,,,,Fourlix

SP500HO
425EXP- Let's add a Scrambler cam, 38mm carb, and
whichever intake manifold fits best, there could be another out there just right for the 38. And a Supertrapp muffler. Hey Rick and AAEN, you listening? There's Hot-Rodding afoot for the
5-speed Polaris! These guys SHIFT! Don't you think they want to go a little faster? Hey Polaris, looks like it would be pretty easy to make a 500EXP H.O. huh?

 

defintitely something im interested in..i was thinking of adding a power kit but now ill have to wait and see what comes out of this..hope it works