I have an XR500 as well, and I wouldn't hit a bull in the ass with the way they start. But there is something wrong with mine, it kicks back furiously every time you kick it can't even ride it now on account of it.Half of the 500's I have seen have a broken kick shaft. I don't know if the later model 500's were better or not, but i think the 600 motor is probably a better choice. Anyonelse have problems with their 500's kicking back? Even if you could put the 500 cylinder,the 500 has a way longer stroke so you would have to have a machine shop and a lot of time and money, it just wouldn't be worth it.
ATC350X,ATC70,1991 RM 250,XR500,TM400,TS400,Foreman400 4X4,Polaris 425 Magnum,ATC 90, 1982 175,1973 Honda Trail 90,1980 CR80,1981 CR80,