I have not needed to buy too many parts for my bike yet Firko, as it came with a good range of spares when I bought it & I haven't put a lot of hours on it . I did buy some gaskets & o-rings from Bert Flood a while back , but I think for cosmetic parts I might have to buy from the U.S . Mine has WP 4054 USD forks & WP rear shock & is a very plush ride , although it feels a bit heavy when compared to my Husaberg. The motor is a bit of a monster though as a previous owner had some head work done by Ron Wood & fitted a big cam . He also went overboard & fitted a 45mm Mikuni flatslide pumper carb , which I think is way too big & sacrifices bottom end power for the sake of eye watering top-end . I will be looking to tame it down in the future & fit a smaller carb . I do have an issue with the A-Trak chain tensioner system , as it only allows 2 or 3 teeth on the front sprocket to drive the chain . Even with a new chain & the biggest front sprocket I can fit , it still seems to jump a tooth occasionally under hard acceleration on rough ground . I may have to make up a new case saver plate that fits as close as possible to the chain .
Unfortunately if you are after an electric start model , then the '89 is the first one that this came out on (I think). I have not seen an ATK with Simons forks , so the one you rode maybe had aftermarket ones fitted . I have always liked the ATK406 because of its simplicity with the aircooled 2 stroke Rotax motor & the linkless single shock rear end . Also on this model ,I think that the airfilter is a pod style right up behind the front numberplate / headlight . There is lots of innovative technology on these bikes .