Honda GX160 Engine History

Honda GX160 Latest Engines (GX160UT1 QHQ4 and GX160UT1 QHG4)

Within the Honda GX160UT1 engine range there are approximately 87 different engine variants. 

These include:-

GX160UT1 SHQ4

GX160UT1 LHQ4

GX160UT1 QHQ4, etc.

These engine codes (QHQ4, SHQ4, etc) relate to the slight modifications made to each engine for the various applications they are used in, for example difference in shaft size, length and shape; or with or without oil alert.  The main components of the GX160UT1 engine (the Cylinder Head, Piston, Con Rod, etc) all remain common.

Only 2 out of the 87 engines are eligible for MSA race meetings (and race meetings that run to the Honda Technical Regulations).  These are the QHQ4 model and from 1^st May 2008 the QHG4 model.

Honda has introduced the QHG4 engine (primarily for the hire kart market) as an engine with stiffer valve springs (part number 14751-ZH8-940), a larger more substantial exhaust that is unlikely to have the baffles break apart (part number 18310-ZH7-V90), and a different Carb Insulator (part number 16211-ZE2-700), which allows a pulse pump to be fitted rather than the traditional method of taking a feed from the crankcase hole.  In addition the engine is shipped without a fuel tank in order to reduce the price of the engine when many remove the tank to fit remote tanks.

These are the only differences to the engine when compared to the GX160UT1 QHQ4 engine.  The exhaust is believed to offer no performance advantage over a De-baffled exhaust with the De-baffled exhaust providing slightly better performance on the dyno.  The valve springs and carb insulator are an easy replacement part that most karters will replace regularly anyway.

Therefore, unless you are in need of a new pair of engines (the QHG4 is slightly cheaper than the QHQ4 as it doesn’t have a fuel tank), the only part that is really worth changing is the valve spring.  Everything else will be the same spec, and most will continue to fit the de-baffled exhaust.

History of the GX160

The GX160 engine was introduced in approximately January 1991 with the GX160K1, with the QHQ4 model being used in prokart racing in the UK.  Engine numbers were GC02-2000001 to GC02-8669999.  However, in approximately late 2000 Honda introduced a new GX160K1 engine that became known amongst karters as the “E-Spec” engine.  The E-Spec engine was introduced from engine number GC02-7664037 onwards and was aimed at helping to reduce emissions.

Changes included the introduction of a Flat Top Piston, and a different Cylinder Head with a larger volume.

In October 2003 Honda introduced a further modification to the GX160K1 engine (still known as the E-Spec) from engine number GC02-8670001 onwards. 

In June 2004 a further modification was made to the GX160K1 engine and the engine numbers now commenced with engine number GCAAK 1000001. 

To confuse matters, Honda then moved production to Thailand and in September 2002 the GX160T1 engine was issued.  Again many of the parts remained the same however new tooling and moulds were used which gave much tighter tolerances. 

The reason for the T1 designation was to record production from the Thailand factory and as can be seen from the dates above there was an overlap between the K-Spec engine (known as the E-Spec amongst karters) and the T-Spec engine.

The T-Spec engine was numbered from engine number GCABT 1000001 and the QHQ4 model was again the only engine allowed in MSA racing.

In March 2005 Honda then introduced the GX160UT engine from engine number GCACK 1000001 and a month later in April 2005 introduced the GX160UT1 engine from engine number GCAFT 1000001.  For both models only engine model QHQ4 was eligible for racing.

The main difference between the UT and UT1 engines over the T-spec engines was:-

·         Flat Top Piston with longer Skirt

·         Thinner Piston Rings

·         Slightly thinner Cylinder Head Gasket

·         Different Cylinder Head offering slightly better cooling but with slightly larger volume

·         Cosmetic changes to the ignition coil and the side case sticker.

By retro-fitting the UT1 Cylinder Head Gasket, Rings and Piston to a T-spec engine effectively brought this up to the same spec as a UT or UT1 engine with the Cylinder Head and Ignition Coil offering no advantage or disadvantage.

From the 1^st May 2008 the Technical Regulations allowed the introduction of the QHG4 model as well as the QHQ4 engine as described above.

Summary of GX160 Kart Engines

* Date introduced by Honda, date engine reached UK may be different.