JOE DIRT 88 Posted June 10, 2018 Doing a rebuild on a XR80. Due to a chipped exhaust valve that inbedded itself into the top of the piston. Weirdest thing. Was wondering about a 50 overbore. I have a cylinder. Would their be a noticeable difference in power and performance over just leaving it stock? Is it worth the money over piston prices? Kinda weighing the advantages and disadvantages before deciding. Thanks. Share this post Link to post Share on other sites
vintagemx Posted June 11, 2018 The piston from a '74-'77 Honda CB400F will work in the XR80 motor and up displacement to 92cc. https://4-stroke.net/library/honda-piston-size-chart.html Share this post Link to post Share on other sites
RBracing Posted June 14, 2018 On 6/11/2018 at 11:08 AM, vintagemx said: The piston from a '74-'77 Honda CB400F will work in the XR80 motor and up displacement to 92cc. https://4-stroke.net/library/honda-piston-size-chart.html I had a Powrol big bore kit in my XR80 back in the day but no one seems to package a big bore kit for the CRF/XR 80 any more. There was one place that had one for like $250? I do remember the CB400F pistons as an option. Working on a 1974 XR75 project that I may put a points XR80 engine in so a big bore piston would be nice to source out that isn't too expensive or else I would just look for a 100 engine. Share this post Link to post Share on other sites
vintagemx Posted June 14, 2018 2 hours ago, RBracing said: I had a Powrol big bore kit in my XR80 back in the day but no one seems to package a big bore kit for the CRF/XR 80 any more. There was one place that had one for like $250? I do remember the CB400F pistons as an option. Working on a 1974 XR75 project that I may put a points XR80 engine in so a big bore piston would be nice to source out that isn't too expensive or else I would just look for a 100 engine. I still have that XR motor sitting in my garage. It’s got a few more goodies than just the big bore. I’m done building XRs, so if you’re interested send me a pm. Share this post Link to post Share on other sites
jscoot116 My Ride Posted June 15, 2018 Yeah I was debating between a xr100 or xr80 for my pit bike. I ended up getting an xr80 as the 100 felt just a tad more than a pit bike. Come time for mods- couldn’t find a thing about BBKs. I ended up swapping it with a 200cc motor and calling it a day lol Share this post Link to post Share on other sites
RBracing Posted January 21 On 6/14/2018 at 5:26 PM, vintagemx said: I still have that XR motor sitting in my garage. It’s got a few more goodies than just the big bore. I’m done building XRs, so if you’re interested send me a pm. PM sent Share this post Link to post Share on other sites
Daniel627 Posted January 22 7 months later lol I have an xr80r with a locked up motor I need to build Share this post Link to post Share on other sites
