400 TRAIL ENGINE MODS - Back to Engine Mods

Reed Spacer
Kit 400

THIS ITEM IS ON SALE!
$25.00!!

For Polaris 400 only. Increases horsepower and extends reed life. A must for big bores, to correct primary compression.

Trail Mod Kit
for 400 Polaris

After installing this kit, just push the throttle for some tire churning, stump pulling power from down low, all the way to the top. The total price completed will save you money too!

Trail Mod Porting

Designed for the 400 Polaris ATV. The trail mod cylinder porting is worth 8 more peak horsepower. Excellent all around performance.

Requirements:An HPD trail or race pipe, clutch kit and forged piston. 92 Octane fuel. Billet head (BHPG12) with girdle kit are recommended.

PART # TMC
• LIST $300.00

Trail Head Mod

Head machining designed for the 400
trail porting and 92 octance pump gas. Improved all around power with
trail porting.

PART # TMH
• LIST $70.00

Bore Cylinder

Send us your cylinder, and we will bore, hone and chamfer the ports.

Fill out this form to send with mods

Remove .04" to .08" material
PART # BORE+
• LIST $75.00

Remove up to .04" material
PART # BORE
• LIST $65.00

Big Bore- Remove .1" or more
PART # BOREBB
• LIST $85.00

Carburetor Boring
(for stock carb)

Off set bore your carb to 35.5 MM. Gives good low end response plus another 1 1/2 horsepower gain..

PART # BOREC
• LIST $60.00

400 Polaris w/trail mod
with stock airbox
PART # 39PWK400TMA
• LIST $300.00

400 Polaris w/trail mod
with clamp-on air filter
PART # 39PWK400TM
• LIST $290.00

Fuel Pump Kit

Power Maxx 416s with 47mm carb and some race mod 400s with 39 PWKs require a fuel pump to supply sufficient fuel flow.
Kit includes high output Mikuni pump. Pulse and fuel line, fittings, filter and installation guide.
You will have to change your needle and seat to use this fuel pump

Fits 98-03 Scrambler & 99-03 Sport and Trail Blazer. Ceramic finish.

PART # ATVP8
• LIST $210.00

Fits all 400s with HPD Pipe. Scramblers, Sports, and Trailblazers.

MTQuiet Muffler

PART # MTQ
• LIST $150.00

Fits all 400s with HPD Pipe.
Scramblers, Sports, and Trailblazers.

MSA Spark Arrestor Muffler

Weighs only 3 lbs. Muffler body is 3 inches in diameter and 12 inches long. This muffler is forestry approved, repackable, and is 93 DB. Aluminum construction only.

PART # MSA
• LIST $153.00

Fits all 400s with HPD Pipe.
Scramblers, Sports, and Trailblazers.

MTD Muffler

Available in black or nickel chrome.

Aggressive Clutch Kits

Kit includes: Helix, weights, 2 springs, installation guide, and shims (if needed).
Aggressive clutch kits are faster accelerating, plus more mid range response. Back shift is improved at all speeds. These kits also improve belt life. All have been tested for accuracy on dynoed engines with on board computers. This is the best performing trail set up.

400 Sport/Scrambler
(Race)
Designed to be used with race ported motor and ATVRP8 pipe.

PART # CK4RM8
• LIST $170.00

400 Sport/Scrambler
(Trail)
With trail pipe and/or trail porting. Higher engagement than stock.

PART # ATVCK4MA
• LIST $170.00

400 Drag Race Mod
Designed to be used with race ported motor and ATVRP8 pipe.

PART # ATVCK4DR
• LIST $170.00

Standard Clutch Kits

Includes: Weights 2 springs, installation guide and shims (if needed).

Piped: 400 Sport, Scrambler & Trail Blazer

Engines with stock porting and HPD pipe. Lowest engagement for pipe. Soft excelleration off the bottom.

PART # ATVCK4P
• LIST $105.00

NEW!!

High Output Ignition Upgrade
for 400 / 416

High Output Ignition Upgrade for 400 / 416

Finely tuned, higher output replacement source coil, ignition coil, and CDI Box. Output is 35% higher voltage and higher amperage than original parts. Now you can gap your plug at .025" or more without any misfiring. Because of the wider gap and higher voltage, horsepower output WILL increase.

NOTE: You must recheck your jetting.
Spark Plug wire and retainer

Ignition Upgrade
PART # PM4IGU
• LIST $290.00

WISECO
Forged Pistons

Due to past experience with broken pistons on modified ATVs, we require WISECO pistons be used on all modified engines, and recommend them for all others. Includes: Piston, rings, pin, and clips.

REQUIRES: Cylinder honing or boring.

Custom
Forged Pistons
400 Big Bore

Billet Head,
Cover & O-Rings

A must have for the Polaris racers and performance riders.

Our billet, 2 piece head, is a complete design, and not just a machined copy of the original stocker. It provides concentric water flow, thus preventing hot spots. Sealed to the cylinder with O-rings to create a metal to metal contact, providing even engine temperatures. The improved combustion chamber pocket and squish area, increases horsepower and torque. Additionally, the head allows girdling through the cylinder to the crankcase, providing a much stronger and durable package.

Girdle kit is optional. Not for use on 416 PowerMAXX.

Trail Mod 400s
Designed for stock, piped or trail mod 400s on 92 octane fuel. Improved torque and horsepower.

Trail Mod 400s
Designed for stock, piped or trail mod 400s on 92 octane fuel, but for 4500 feet or higher altitude.

Trail or Race Mod 400s
Designed for 105 octane race gas on trail or race mod engines. Great horsepower.

Race Mod 400s
Designed for use with 110 plus motor octane fuels on race mod engines. Best horsepower.

Billet Head Girdle Kit

For Polaris 400 cyl. only (not for use on 416 POWER MAXX products).

For Polaris 400 cyl. only (not for use on 416 POWER MAXX products). Send in Cylinder to HPD for modification.

Replacement Chambers for Billet Heads

Often copied but never duplicated.

ChamberType: High Alt.Pump Gas 400
Gas Type: 92 Octane/Pump

ChamberType: Race Gas
Gas Type: 110 Octane/Race

These kits are industry leaders for providing smooth and precise upshift and backshift, which improves your efficiency, performance and durability. Tunable with custom cam angles and springs. Twin roller operating in enclosed helix track.

MUST STATE MODEL OF MACHINE IN "COMMENTS" SECTION OF ORDER FORM.

TAS99 Team Secondary Clutch Springs

Secondary springs control shift rate.
Fine-tune your secondary clutch with TEAM springs manufactured to the most exacting specifications.
Spring Height at 2.4" - 1.4"

Black/Red
120-185 Wt
PART # 210090
• LIST $19.95

TAS03X Team Secondary
Clutch Springs
Chart 1
Load Heights at 2.05" + 1.05"


Secondary springs control shift rate.
Fine-tune your secondary clutch with TEAM springs manufactured to the most exacting specifications.

Bright Green/Purple
105-185 Wt
PART #210314-001
• LIST $19.95

TAS03X Team Secondary
Clutch Springs
Chart 2
Load Height at 2.0" - 1.0"


Secondary springs control shift rate.
Fine-tune your secondary clutch with TEAM springs manufactured to the most exacting specifications.

Green / White
105-185 Wt
PART # 210215
• LIST $19.95

Team Helix's

EBS Helix's Only