ATC70/TRX70, All years
There are no installation instructions, but if you can replace your piston, you can install a big bore kit. If you don't have any experience working on your engine, we highly recommend having a professional technician installed. The parts are installed in the same manner as OEM parts. 
All performance parts have no warranty.

Billet Valve Covers

  • Available in Red or Black
  • Fits: ATC/TRX 70, CT70, Z50, Most 90-125cc Chinese Engines

$22.00 set

Heavy Duty Auto Clutch Kit

  • Fits all years of the Z50, CT70 ATC/TRX 70.
  • Complete modern style clutch w/separate discs and plates. Has more friction surfaces for a stronger engagement. Great for larger displacement motors. Recommended for the stoker-big bore kit.


Engine Mount Bolts

  • Stainless Steel Allen Head or Standard Head
  • 120mm Long

$2.50 ea

Neutral Indicator

Allen Engine Bolt Kit

OEM Honda Cam Gear Cover

Billet Dip Stick

  • Available in Red or Black
  • Fits: ATC/TRX 70, CT70, Z50


To place a order call (530)533-6069 or email us at Free shipping over $250.00 excludes fenders, wheels/tire ship for $40.00, and engines ship for $47.00​

70cc Replacement Piston 

  • Includes rings, clips and pin.
  • Piston and Rings

70cc Complete Gasket kit

Stator Plate Bolt
$1.00 ea

Engine Fastener Kit (Phillips head)

  • Covers top and bottom end of motor


OEM Honda Dip Stick

  • Fits all years, ATC/TRX70


Atc/Trx70 Performance and Parts

88cc Cylinder Kit ( OUT OF STOCK )

  • Lightweight aluminum cylinder w/steel sleeve. Cast in mounts for aftermarket skid plates. Oversized fins for efficient heat dissipation. High compression piston w/rings, pin and clips.
  • Top end gasket set.
  • No case machining needed
  • Fits all years ATC70 & TRX70


Magnetic Drain Plug

51mm Stroker Crankshaft

  • This is an affordable kit that will convert your TB 88cc Race Head kit into a powerful open class 108cc engine (much more powerful than the common Chinese 107 and 125cc engines). This crankshaft can only be used with the 88cc kit above in the ATC70. It requires a different piston than the standard 88cc kit. If you already have a TB 88cc kit you will need to purchase the new piston/rings @ $59.00. When purchasing the entire big bore/stroker we will include the correct piston.
  • The 6volt high volume oil pump is required with this crank. You will also need to upgrade your clutch. Scroll down the page to see these parts
  • Includes center case gasket.
  • Installation of this part requires the engine cases to be split. Unless you are very experienced at working on these engines, 
    we recommend having a professional technician do the work. All performance parts have no warranty. 


  • The ATC70 had two different crankshafts. The 78-80 has a shorter crank than the 81-85. Let us know which engine you have to ensure you receive the correct crankshaft.

OEM Neutral Indicator

Woodruff/Flywheel Key

  • ATC/TRX70 engines


Flywheel Nut

  • ATC/TRX70 Engine
  • Fits china engines


OEM Style Tappet/Valve Covers
$19.00 set

6Volt High volume Oil Pump 

  • Highly Recommended when using a big bore and required with the big bore-stroker kit.
  • Requires drilling out of the oil outlet on case to 2mm or 5/64".
  • Must replace OEM pump shaft with new included shaft.
  • Requires removal of clutch assembly and cylinder or stator plate removal to complete install.

Clutch Sidecase Gasket sold separately

Cam Chain Roller Bolt

Clutch Nut Tool

  • Fits all years of the ATC/TRX/CT70, Z50
  • This tool is a must when installing your clutch and clutch kits. The clutch nut needs to be tightened properly to prevent spline damage. Do NOT tighten with a hammer and screwdriver.


88cc Full Kit  ( OUT OF STOCK )

  • Trailbikes kit we have made changes to better fit the ATC/TRX70.
  • Carb has been replaced with a 20mm OEM style that has same petcock and can use the factory thumb throttle cable.
  • Features:
  • Lightweight aluminum cylinder w/steel sleeve
  • Cast in mounts for aftermarket skid plates
  • Oversized fins for efficient heat dissipation
  • 52mm High compression piston w/rings pin and clips
  • Head Gasket Kit.
  • Race head with 25/22mm valves and a high performance camshaft w/Honda cam sprocket
  • Foam air filter
  • No case machining needed
  • Fits all years ATC70 & TRX70


Flywheel Puller Tool

  • Fits most small Honda & Chinese Engines



Cam Chain

  • All years ATC70 & TRX70


Heavy Duty Spring Set

  • Replace the old springs with this new stronger set for better clutch engagement. Recommended upgrade for big bore kits and strokers


Auto Clutch Replacement Kit

  • Includes new plate/disc and side case gasket.
  • Recommended upgrade for big bore kits along with HD springs.


if(screen.availLeft) { top.moveTo(screen.availLeft, screen.availTop); } else { top.moveTo(0,0); } top.resizeTo(screen.availWidth, screen.availHeight)