K25

An IAME Komet K25 125cc reed valve engine of the new (1997) type, with a Horstman 95 single disc dry clutch.

An IAME Komet K25 of the new (1997) type with the original thick (POP/Promo95) exhaust mounted on a kart.

A look inside an IAME K25 cylinder barrel with a 54.00mm piston. This barrel and piston are the same as used for the Parilla Leopard.

An IAME Komet K25 engine of the old (pre 1997) type, with an Ibea L2 carburetor and PVL ignition.

An IAME Parilla Leopard clutch mounted to an IAME Komet K25 engine of the old (pre-1997) type.

An IAME Komet K25 engine of the newer (1997) type, with an original thick exhaust and a 100cc exhaust.

Komet

IAME Komet K25

The IAME Komet K25 is a water cooled 125cc clutched reed valve two stroke engine that can be seen as the predecessor to many modern day 125cc TaG engines. As opposed to its TaG descendants, it has no onboard electric starter. Since it is a clutched engine, an external starter is needed, similar to the ones used for JICA engines. Other than that it is very similar to the IAME Parilla Leopard TaG engine, with many parts like the cylinder barrel, head, exhaust manifold (characteristic with 3 stud holes) and pistons interchangeable. Pistons can also be interchanged with the later IAME X30 and are available for bore sizes from 54.00mm to 54.28mm, some aftermarket ones a little bigger.

The Komet K25 was introduced in 1991 and from 1994 onwards was raced in Germany in the POP class, in Sweden in the Sport2000 class and in The Netherlands in the Promo95 class. Possibly it was also raced in France and Denmark, but this needs further information. Production of the engine was discontinued somewhere around 2000-2001 but it is still, especially in Germany, a very popular hobby engine. It is usually slightly quicker than the Rotax FR125 Max due to the lack of rev limiter and lower weight with no starter or battery.

Two versions exist. The early version without cooling ribs on the crankcase and a later updated version (1997 onwards) with cooling ribs on the crankcase, sometimes referred to as the K25-RL.

K25's were sold with a very thick exhaust pipe with damping material wrapped inside, intended to bring down the noise level. Combined with water cooling, these engines were considered to be very quiet in the early 1990's era of loud air-cooled 100cc motors. However, many people figured out that the engine would perform better and look prettier with a normal 100cc pipe, hence these days it is rare to find a K25 with the original thick pipe.

The K25 came originally with a Horstman 95 clutch as used on earlier JICA engines. It can be easily exchanged for the later JICA Horstman 98 model. With some small modifications to the crankshaft it is also possible to mount the clutch of a Leopard. This has the advantage that sprockets can be replaced independent of clutch drum, saving costs. Furthermore, the Leopard clutch is known to be of a more sturdy and heat resistant design than the older Horstmans.

The ignition of the K25 is of the PVL type, with a 105 458 coil, 1051 stator on a 93.95mm backplate and 951 rotor.

The standard carburetor is a Tillotson HL-334 but other types can be used as well, such as the Ibea L2.

Like the Leopard, the K25 does not have a balancing shaft. The engine runs at similar top revs as 100cc ICA engines, but due to the heavier piston assembly of a 54mm 125cc piston, vibrations are known to be an issue with these engines. There are known instances of fractured chassis tubes near the engine mount, often right next to the bearing carrier cradle. Sometimes an extra plate is mounted between the engine and engine mount to work around this issue.

Ignition timing: TBD.
Spark plug: Heat range similar to NGK 9 for cold weather and NGK 10 for normal to hot weather.
Main crankshaft bearings: 6205 C4.
Oil seals: FPJ (teflon) double lip, 35mm O/D, 20mm I/D, 7mm thick.
Piston pin: 14mm O/D, 44mm long.
Piston pin needle bearing: TBD mm I/D, TBD mm O/D, TBD mm wide.
Big end pin: 18mm O/D, 47mm long.
Big end needle bearing: TBD mm I/D, TBD mm O/D, TBD mm wide.
Big end thrust washers: 18mm I/D, 33.5mm O/D, 1mm thick.