Technical Information

1.) Spark Plugs: Gap = .035

Cross Reference for T.P. Engines

Autolite          Champion              NGK             Harley Davidson   

4164                  RA8HC              DCPR7E           6R12


Electrode Tip Material: Resistor
Reach: 3/4 in
Resistor: Suppressor
Seat Type: Gasket
Thread Diameter: 12 mm
Tip Configuration: Power
Wrench Diameter: 11/16 in


TP ENGINEERING INC. recommends SAE 20W50 mineral-based motor oil for all Pro-Series engines. Available at any Harley Davidson Dealership.

We don’t recommend the use of synthetic oil.

Oil Filter* (Use only 40 micron filter — H-D Part #63796-77A) on all Classic EVO oil pumps.

If your engine is equipped with our new Smart oil pump;

The Smart Pump allows the use of a 10 or 40 micron filter.
10 Micron – H-D Part #63798-99 (filters smaller particles)
40 Micron – H-D Part #63796-77A (standard Evo filter)



Always ensure there is adequate ventilation when running any internal combustion engine.

2.)  New Engine Break-in Procedure

CAUTION: This is an-air cooled engine that relies on airflow for cooling. Do not allow engine to overheat by subjecting it to prolonged periods of idle.

Note; If operating your engine at temperatures of 70 degrees F or below, use SAE 10W40; otherwise use SAE 20W50 motor oil for initial 100-mile break-in. At 100 miles, change engine oil and filter; use SAE 20W50 mineral-based motor oil only. Do not use any additives or synthetic motor oils for the first 5,000 miles.

Make an effort to vary engine speed during the first 500 miles. Operate the engine at speeds between 1,600 and 2,500 RPM whenever possible. Occasional burts of speed followed by quick deceleration during this period may be beneficial. Limit engine speed to 3,800 RPM and below during the first 1,000 miles. Never exceed 5,500 RPM. At 1,000 miles, change engine oil and filter; use 20W50 mineral -based motor oil.

Note; Some oil consumption is normal with a new engine. Check your oil level often with engine hot after allowing engine to idle for 30 seconds. TP recommends SAE 20W50 mineral-based motor oil for all Pro-Series engines.


3.) Owner’s Manuals

Crank Trigger = Thunderheart Ignition Instructions

Tp / Crane Hi-4 Ignition: 89-0107 Instructions –

Crane Cams Istructions

Mikuni carburetor HSR 45mm

Instructions – Top End Assembly

Specifications – Engine Torque specs

Troubleshooting oil coming out top end breathers

            Wet-sump = Procedure: how to clear oil pump check valves

Oil Pumps:

Identifying Oil Pumps

Classic Oil Pump Installation Instruction

Classic – Oil Pump Connection

Classic Oil Pump Connection Diagram

 Smart – Oil pump Connection Diagram

Smart – Oil Pump – installation Instructions.

Oil Filter Mount: Diagram

Pro-Vent Rocker Boxes Instructions:


BIG DOG / 117


4.) Pushrod Adjustment

note:    Replacement of the stock pushrods will require rocker arm disassembly.


1 – Remove spark plug and rotate engine until the front piston is at the top of its stroke, with both front lifters at the lowest position ( TDCC – top dead center, compression ).

2 – Remove pushrod cover clips and lift cover assemblies to view lifters.

3 – Loosen the locknuts with (2) 3/8 open-end wrenches and shorten the pushrods until they are totally loose.

4 – Hold the exhaust pushrod body and turn the bottom counter-clockwise to remove lash between the lifter and the rocker arm.

5 – Mark the position of the flats, and with your wrench hold the top nut in place and turn the bottom nut of the pushrod 3 full turns (18 flats). Now tighten the middle locknut against the bottom nut. Note:  Allow sufficient time for lifter to bleed down (at least 10 minutes) before adjusting the intake pushrod.

  ♦Caution♦  __  Failure to allow hydraulic lifter to bleed down before rotating the engine or adjusting the other pushrod could result in valve – to – valve contact and serious valve train damage. Lifters are bled down when pushrod can be turned with your fingertips.

6 – Repeat above procedures for rear cylinder.

7 – Reinstall spark plugs, pushrod tubes and tube clips.


 TP ENGINEERING introduced  new pushrods for our late 2009 engines.

The new pushrods can be adjusted using the same procedures as above, except the locknuts are bigger (7/16) And 4 full turns are needed to adjust them.


124-10    650 Lift Cam Specs

124 cam A


123-10   600 Lift Cam Specs

123 cam


122-10     600 Lift Cam Specs

122 cam