Originally Posted by pennswoodsed
Should be interesting, 83 or 84 KTM 's and some years ATK s 600 had the Rotax 604 ? engine .
That's a good point, the 604 should be a near bolt-in given how many parts the ATK shared with the KTM. The swingarm and rear frame area looks very similar. However those engines are not easy to find. There are about 10 F650 engines on ebay right now, and I've never seen a 604 being parted out. I'll keep an eye out though.