Which GY6 CYLINDER KIT 155cc (58.5mm)  By  scutman (Read 6,760 times)

If you are going to do the wok of installing a kit, go a bit bigger. These should fit without boring the case, and are what I would use if I were to kit a 150cc gy6 engine.

www.ebay.com/itm/GY6-150cc-High-Performance-60mm-Taiwanese-High-Compression-Big-Bore-Kit-163cc-/310982298449?pt=Motorcycles_Parts_Accessories&hash=item4867fd4b51

www.scooterworks.com/ncy-cylinder-kit--aluminum--61mm--171cc---genuine-gy6-products-1028.php#.U7XeOUC0t39

I'm sorry but I completely disagree I went with a 58.5 and a 58.5 head , and with my other upgrades I've picked up 12 mph . I was once told that I should have went with a 60mm kit because it's pointless to go with the 58.5 . So I ask is it now pointless for me to go with the 60mm kit since I have a 58.5 ? will I notice no difference ? First is your going to get a better quality kit then stock next it will be 1.5 mm bigger . This was enough for my scoot to push my taller final drive gears , that and the other mods I've done . If u would rather buy the 60mm kit I'm sure you will notice even more of a gain but don't be discouraged to go with the 58.5 .

I'd like to go with the 61mm kit also , maybe at the end of the season I'll get one or income tax time .

i agree also. Save up and get a Taida 61mm kit. It requires no boring of the crankcase. Drowsports.com has them. 

Yes it is . I'm not sure what other mods You have done if any , but u will need to go with a performance head and exhaust plus a few other smaller mods to get the performance you want . I see the point the others are trying to make , it's only 1.5 mm bigger but I've actually installed one on mine and I had better then expected results . Also the cam makes a big difference I really wish I knew which cam I have , I ordered a so called racing cam from eBay that was not labeled and it turned out to be a night and day difference from the stock cam . I topped out around 55 mph stock and now I'm around 67 mph . From what I know my speedo is spot on . I Test it by riding along side of our car at 50mph which has gps and it was spot on " not a perfect method but it worked" even if it was a mph off my speedo went from 55 to 67 on a straight stretch which is a 12mph gain . On the slightest decline I gain an easy 3 mph and the slightest incline I loose about 5 to 7 mph. I also tuned my cvt so that I can hit 7500 rpms on a straight stretch , this allows me to get the all the performance I can out of the engine and mods that I can .