Engine Information – X30 Dirt


BORE: 54.00 mm
STROKE: 54.00 mm
COOLING: Water Cooled
CARBURETOR: Tillotson HW27A or Tryton 27
MAX HORSE POWER: 30 HP between 11.000 and 11.250 rpm
MAX TORQUE: 19.5 Nm between 10.250 and 10.500 rpm
DRIVE: Dry centrifugal clutch
FUEL: Premium Unleaded
MIXTURE: 16:1 – 25:1 Caster oil
WEIGHT: 12 kg without accessories
MAX RPM: 15800 RPM Limited
STARTING: On Board Electric Starter


Reed Valves

The reed valves require periodic checking, as they can be prone to breaking or chipping.

3 Meetings

Gear Oil, this involves checking the level via the 14mm brass bolt at the front of the engine.

Bendix Drive, the bend area is subject to collecting dirt, which in the long run can damage the bendix’s ability to start the engine.  Cleaning requires removing the plastic clutch cover and bend cover and spray some degreaser, along with the use of compressed air to clean the area

Clutch, The clutch should be serviced every time the front sprocket is changed.  At this time the clutch bearing should be changed or re-lubed, the inside of the drum cleaned with brake cleaner, and if required the clutch pads cleaned with either 800 grit sandpaper or scotch brite

3-6 Meetings

Carburettor, Carby maintenance is both a factor of use and time.  If you do not use the engine for some time, then you will need to service the carby, even if it has not been used that often.  Carby servicing will require the diaphragms to be replaced in a basic service, up to the needle and seat, or other components of the carby to bring it back to original condition.

5-15 Meetings

The engine will require a top end rebuild during this period.  Depending on the level of competition you are at, the Piston & Ring, Small End Bearing, Piston Pin, O-Rings and gaskets will need to be changed.  A general indication that your engine may be due for a top end rebuild is that you may notice the bottom end power of your engine decrease.  The engine should not exceed 10 hours before a top end rebuild is performed.

30-45 Meetings

During this period you engine will need a major rebuild.  This included a top end rebuild along with replacing the Con-Rod, Big End Bearing, Crankpin, Thrush Washers, Main Bearings, Seals.  The engine should not exceed 30 hours before this service is performed.


Head and Cylinder Nut 13-16 ft-lb / 18-22 Nm

Carby Fixing Nut/Stud 6-8 ft-lb / 8-10 Nm

Ignition Rotor Nut 14-19 ft-lb / 20-26 Nm

Clutch Drum Nut 22-29 ft-lb / 30-40 Nm

Starter Ring Fixing Nut 73-80 ft-lb / 100-110 Nm

Spark Plug 14-19 ft-lb / 20-26 Nm

Exhaust Nut 13-16 ft-lb / 18-22 Nm


The break-in of the engine must be performed following a few fundamental rules:

  1. Adjust the carburetion. Start with an adjustment on the rich side.
  2. Warm the engine gradually for about 10 minutes at half throttle, making some laps at low speed, gently closing and opening the carb. throttle (if a tachometer is installed never exceed 11.000 ÷ 12.000 RPM). Never keep the same RPM for a long time.
  3. Increase the speed for 10 minutes at 3⁄4 throttle opening. Never keep the same RPM for a long time.

4. Increase the speed for 10 minutes, at max. speed on the twisty parts of the circuit and making the engine rich at half straight (cover with the hand for an instant the holes on the air filter keeping the throttle wide open).

Once the break-in is over and the engine is cold, check the torque of the exhaust header nuts as, during the break-in, the nuts tend to become loose.

Lightning Karts also offer a dyno run-in session that allows you to pick up your engine, bolt it on and go racing.  No matter who built it we are happy to offer this service to save you valuable time at the track.


Tryton Carburettor

L = 1hr 5min

H = 1hr 5 min

The recommended jet settings for the Tryton carby are 1 hour and 5 minutes on the low and 1 hour and 5 minutes on the high, depending on location and climate it may be necessary to deviate slightly from these settings.  Once the optimal setting is found it is uncommon to have to adjust much, if at all from this setting.

The recommended pop off pressure is 8.5-10psi depending on location and climate, generally 10psi is a good starting point. With lever height it’s best to start with the bottom of the lever level with the carburettor body, if carby feels to be running out of fuel try raising the lever even more.

Tillotson Carburettor

L – 1hr 5 min to 1hr 10min

H = 1hr 25min to 1hr 30min

The recommended jet settings for the Tillotson HW27A carbs are 1 hr 5 mins to 1hr 10 mins on the Low and 1hr 25 mins to 1hr 30 min on the High.  The pop off pressure should be set at 10psi with the lever height flush to the meter body.

* Please keep in mind these settings are a basic starting point and different weather conditions, type of fuel & fuel quality may require slight adjustments from the above.


Original Straight Muffler and Header

IAME performed extensive testing when developing the X30 engine and as a result the recommended setting of 435mm to 445mm for high speed tracks and 445mm to 455mm for tighter tracks.  This is measured from the flange to the first weld on the muffler.  It generally equate’s to between 50mm and 70mm flex lengths. The rule for flex is that shorter flex will produce more power in the higher RPM range and the longer the flex, more power will be produced in the lower RPM range. 5mm increments will be fine tuning while 10mm increments should produce a noticeable difference.X30 Exhaust Notes — Fox + Son Karting

New 2020 Bent Muffler

The 2020 Muffler no longer uses flex, but is supplied with a 3mm aluminium spacer that can be fitted between the cylinder and exhaust manifold.  Fitting this 3mm spacer is the equivalent of adding 10mm of flex with the older muffler style.


The recommended plugs are as follows

NGK – B9EG, BR9EIX or B9ES.    In warmer conditions a 9.5 or 10 heat range plug can be used

DENSON I27.  In warmer conditions a 29 or 31 heat range plug can be used


The IAME X30 can run in-between 16:1 and 25:1 but we recommend to use 18:1 with a majority of oils.  To determine the correct amount of oil please use our oil/fuel ratio chart.

Click here for oil/fuel ratio chart


We recommend the following oils for the X30 engine – Caster oils

Engine/Fuel Oil

Putoline Caster R, Shell Racing M or Maxima Caster 927

Gear Oil – aprox 40ml, fill until oil comes out of the front oil level plug

Parilla Gear Oil, Maxima Gear Oil or XPS/Xeramic Gear Oil, SAE 30


Maxima Cool-Aid Radiator Coolant



The X30 ignition has a rev limiter and engages at 15,800rpm  It is a soft cut limiter and works by retarding the ignition to a point that the engine produces no more power. As it is a soft cut limiter it is not unusual for the engine to rev past the limiter when in a draft or at the end of a long straight when using a high gearing.