Enduro Engineering
Since the early 2000’s the trend has been to utilize MX racing bikes as the standard for Enduro motorcycles. This was especially initiated by the 2-stroke engine designs conversion to 4-stroke engine designs, which was done to fulfill regulatory trends. Enduro or then called ‘Trail-bikes’ or ‘Dual-sports’ (for their capability of moderate off-road and moderate street performance and yet excelling neither one) had traditionally a much higher proportion of the 4-stroke engine models.
The power-to-weight ration of these 4-stroke bikes was nothing to shout about by today’s standards, and that was the result of the lack of importance on meeting a weight lower-limit. A sudden emphasis on power-to-weight ratios came about with the conversion of the MX bikes to the 4-stroke engines, as the 125 and 250 MX classes have minimum weight limits. As soon as these bikes entered the production stage, their manufacturers came to a decision to re-configure the existing 4-stroke MX lineup for the Enduro, instead of having to invent the next generation of Enduro type 4-stroke bikes.
So what now? Well, the end result of all this is that today the 4-stroke Enduro motorcycles are definitely lighter and more powerful than ever, yet at the same time share the same characteristics as the MX bikes. These originally MX bikes cannot stand up to the harshness of long-term Enduro use. In order to achieve higher power and lower weight, many compromises had to be made by the manufacturers (lighter materials, thinner walls, stressful design, etc). The disadvantages of all this are not always obvious in MX when the races are short and when the bikes are comprehensively serviced after every event or even replaced after every season for the very serious riders.
These compromises became obvious in Enduro racing when the bikes had to withstand the harsh demands of an Enduro race. For example, take the 2004 Honda CRF250X Enduro motorcycle, which was developed based on the CRF250R MX bike. The valves needed constant adjustments and even replacements, and neither procedure is to be taken lightly.
This of course has been rectified with the 2006 models with the change of valve-seat material on the cylinder head. In comparison, the similar Husgvarna model TE250 which is especially built for enduro racing is not only low maintenance but the types of maintenance needed on these enduro bikes are easier to perform as the bike was designed specifically with those procedures in mind.