Honda 400EX HP4 Valve Train Kit

Honda 400EX HP4 Valve Train Kit

With today's modern ATV 4-Stroke engines, making additional Horsepower is no easy task...This makes it critical that Engine Tuners have the Experience, Knowledge and Equipment to do the job properly.

Duncan Racing International's HP4 Valve Train Kit is designed to give you the utmost in performance and reliability by using the most advanced equipment and techniques in the industry. All porting work is performed by our master technician and valve seat cutting is done on our in-house SERDI valve grinding machine.

CORE REQUIRED : Stock Camshaft.
No Billet camshaft available for this model

DR-196K DRI Valve Train HP4 Kit *$950.00
Includes: Hardfaced camshaft (see options below), HD Valve springs, 4 shortened guides, 4-piece Big valve kit (+1mm IN, EX)
Kit must be installed by a trained professional
Notes: 1, 4, 5

DR-196KP DRI Valve Train HP4 Kit w/Porting $1395.00
Includes: Hardfaced camshaft (see options below), HD Valve springs, 4 shortened guides, 4-piece Big valve kit (+1mm IN, EX), DRI Head porting and SERDI Valve Seat Cut and Assembly *
*Customer must send in head for modification or purchase new head from DRI for $480.45
Notes: 1, 4, 5



X1H Grind Camshaft
Part #: MC-196X1-H
Specifications: Bottom/Midrange Cam, Lift: .346", Duration 246°
Application: Woods/Cross Country
Notes: 1, 4, 5

X2H Grind Camshaft
Part #: MC-196X2-H
Specifications: Midrange/Top End Cam, Lift: .378", Duration 254°
Application: Motocross/Sand Dune Riding
Notes: 1, 4, 5

X6H Grind Camshaft
Part #: MC-196X6-H
Specifications: Maximum Top End Cam, Lift: .402"/.385", Duration 270°/262°
Application: TT/Drag Racing
Notes: 1, 2, 3, 4, 5

IMPORTANT NOTES 1.HD Valve Springs are required for this camshaft.
2.Shortened Bronze Guides are required for this camshaft.
3.New or modified piston required for this camshaft. Additional valve pocket relief in piston is required due to increased camshaft lift.
4.Customer must send in stock camshaft core. If no core is supplied, customer must pay core charge of $219.00
5.Customer must send in stock rocker arm cores. The poor quality of the OEM hardfacing requires that the rocker arms be re-hardfaced to match the camshaft. The price for hardfacing rocker arms is $75.00 per arm (4 qty). This is mandatory for warranty. If no cores are supplied, customer must pay rocker arm core charge of $185.00.

No Billet camshaft available for this model.

These cams use stock OEM cam sprockets or aftermarket slotted/adjustable cam sprockets.

The cams uses stock OEM rocker arms. Due to poor quality OEM hardfacing, it is highly recommended that the (4 qty) stock rockers are welded and rehardfaced to match cams. Additional $65.00 charge per rocker arm (4 qty) applies. This is mandatory for warranty.

These camshafts use the stock OEM compression release mechanism, installed and set as per the OEM Honda service manual.

In-House Cylinder Head Porting* (by Master Technician)
*Valve guides are removed during porting process to allow for greater port reconfiguration

Port Design Modifications Aided by In-House Flow Bench Testing and Computerized Port Mapping Software

Precision Valve Seat Machining and Reconfiguration*
*DRI uses in-house SERDI Valve Seat Cutting Machine used by F1, CART and NASCAR.

Big Valve Kits (Stainless Steel or Titanium)

Heavy Duty Valve Spring Kits*
*With Titanium Retainers, Mandatory with High Performance Valve Trains

AMPCO 45 Shortened Valve Guides

Camshafts of the Highest Quality Made in the USA

All Head Work Done In-House for Reasonable Turnaround Delivery Time.

Customers Can Send In Their Head for Modification or DRI Carries New OEM Heads.

HP4 Kits with porting offer gains up to 5 HP*.
*Results vary depending on camshaft profile and piston compression.

For maximum performance, it is highly recommended to use a Fat Boy 4 Complete Exhaust and Vortex Ignition with all HP4 Kits.

Big Bore Kits and alternate compression ratio pistons are also available to use in conjunction with the HP4 Kit. Check the Big Bore Kit and Piston sections on our site for more info.

IMPORTANT NOTE When installing a high performance camshaft it is the responsibility of the engine assembler to check and confirm that the piston to valve clearance is adequate. Minimum clearance is .060" from valve to piston at peak lift. Tolerances can and will vary from engine to engine. There is not substitute for checking that these tolerances are correct. This is especially critical when mixing camshaft and pistons from different engine builders. One of the correct and easiest ways of checking this is by using the "claying the piston dome" method.
Call DRI or consult a professional technician.

Kits include Camshaft(s), HD Valve Springs, Shortened Valve Guides and Big Valve Kit. The HP4 kit is the ultimate valve train upgrade for your sport or racing ATV.
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