Like Jim said...........it's not a big deal but if you want it corrected, it can be adjusted within a small range with the stem adjustment. If I remember correctly is can be adjusted about 10mm if you split the total difference between both fork stems. Mine was off from the factory by about 5mm and I corrected it when I installed RaceTec guts. The proper way to correct the offset length is by fitting the proper DIFFERENT length spring spacers to compensate for the single top out spring in the left leg but that would require a lot of trial and error through assembly and disassembly of the forks until you got the spacer length right.
The quick and easy adjustment is accomplished with the thread height of the stem as it screws into the tube cap. The adjustment is fixed (held) by the lock nut on the stem thread. This adjustment is there to make allowance for the compressing of the short top out spring in the left fork leg when fully assembled. If you change to stiffer fork springs, the top out spring will be compressed more using aftermarket springs as compared to an OEM spring and the fork length difference will be greater as a result. While it's not a deal breaker in general, it's not a great design IMHO because having two different length legs makes getting the axle in place a pain and it does cause more spring preload in one leg versus the other. That unevenness causes the (already undersized axle) to be stressed more than if the both legs had the same spring tension in them. While it may not seem to be a lot of difference with the legs fully extended, the force it takes to make them equal at full extension will be multiplied by a factor of five times (the total inches of fork travel) when the forks are fully compressed. If your forks are off by only 5mm at full extension, try to compress them 1 inch (25mm) and get a feel of the force it takes to do that. That is the amount of offset force difference the axle is having to tolerate while trying to maintain fork alignment at full fork compression. That difference also equates to uneven wear in the fork slider bushings due to the additional side loading. This is all because Honda uses a top out spring in only one fork. If they had one in each fork there would be no issue or concern. While it's not the best design, it is a compromise Honda accepts for cost reasons and it works OK for the most part in this light dampening duty service. There are always tradeoff for a manufacturer. Honda uses only a single damper valve assembly in this fork design and that generates a lot of uneven forces because all of the dampening occurs in only the right fork............ again for cost reasons.
So adjust the top stem to compensate when reassembling the forks as close as you can get it.
