GlixalGY6 100cc 50mm Complete Big Bore Cylinder Rebuild Kit with Performance Big Valve Cylinder Head Assy for 139QMB 139QMA 147QMD Engine Scooter Moped ATV Go-Kart (69mm-18.5/20.5mm Larger Valves)

I'm editing my review, since I just had to teardown my engine today. The exhaust valve spring broke. So I am gonna replace the springs this weekend. Luckily nothing else was damaged. Other than that the kit has been good. The cdi box was junk (good luck finding a decent cdi box for a 50cc) and the exhaust studs are junk. So if I was doing this again, I would get better studs for the exhaust and try to get higher quality valve springs.This kit is such a great deal. Before this kit my scooter had a top speed of 38mph and going up hills it would drop down to 10mph sometimes. I put this kit on and the acceleration is awesome. I have no problem keeping up with with traffic now and even steep hills I can cruise over 30mph. I'm waiting to break in the motor before I really find my top speed, but I've had it up to 45mph, GPS verified so far. The new ignition system, variator weights, and clutch springs are a great bonus. Installation is easy enough.I left the engine on the bike. You'll need a socket set with 8-10mm shallow and deep sockets, feeler gauges, torque wrench something to clean any old gasket material and screwdrivers and wrenches. A hobby mechanic should be able to complete this install in under 5 hours. Other upgrades I have done so far are a new carb with 85 main jet, free flowing air filter new variator and weights and black performance exhaust. I got a new 2000rpm clutch but I haven't installed it yet. All ordered off Amazon!A final note. This kit will make your 49-50cc sooter 82cc not 100cc. But those 32cc will feel like 100 for sure.

great kit. i have used this kit several times on several engines. parts are good quality, gaskets fit great. i really have no complaints with this kit at all.

Less than 50 miles and the exhaust valve blew and trashed the piston. Everything was done by a master mechanic, so no worries there. It's a easy bolt on but the valve seating was defective. Now I have crazy amounts of metal shaving into block and no scoot scoot. More labor ($$$) and time. I have a replacement kit on the way after contacting amazon but doesn't make up for having to tear the block all the way down to rid of the shavings,(shattered metal) and a reinstall due to faulty part/s

So for starters my moped had low compression because my piston rings where bad so I got this kit and when I got it everything seems pretty good but one of the problems was the piston rings that came with the piston in this kit where completely flush with the piston and they are not supposed to be flush so I wasn't getting any compression so I ordered a piston kit from trkimal theirs was correct so I tossed it all together and after a couple minutes of riding my moped I lost all power so I looked into it and found that the rocker arms that came with it broke so if your rocker arms are bad I would just buy a different pair but overall this kit isn't too bad I used to only be able to go 30 miles a hour on my znen wolf rx50 now I can reach a little over 45 miles a hour and the acceleration is so much faster also if you don't know the torgue specs for the rocker arms it should be 14 ft-lbs and I set my rocker arm gaps to 00.3mm intake and 00.4 exhaust

Everything went together smooth no problems and it runs great gets my little scooter up to 45 now with the added roller weights and springs for the clutch got about 40 hours on the motor we’ll see how long she holds up.

Great kit. Made my 50cc scooter much more capable when it came to keeping up with traffic and climbing hills. Gives a very noticable boost in power, especially off-the-line torque. Everything is high quality and very well manufactured, but that doesn't mean anything if you don't do your research and take your time with the installation. When handling such small parts, it can be relatively easy to make a costly mistake. Everything bolts right on, and fits together as it should with no modification necessary. I've put over a thousand miles on mine and had no issues outside of those caused by my own inexperience and abuse hahaha. Couldn't be happier with my purchase!!!

I regret buying this it works for two weeks then give out like this multiple reviews say it

Everything feels to be Good quality, and went together smoothly. My friends all have this kit and have put several 1000s of mile on thiers. Anyone saying that a rocker arm broke or something to that effect didn't install the arms in the kit... or the oil pump both come because they are nessasary and are slightly different for oem.Now I did decide to install a new 20mm carb from the same seller and landed on a 88 main jet for it (sold separately)I haven't installed the yellow tourqe springs yet (new clutch coming) but I've already installed the sliders in the varator right now I'm reaching just shy of 50 mph on gps with room for improvement.It's definitely got the extra power to go ahead with a gear up kit. now it will climb hills while accelerating no problem and maintains speed on giant hills. (It also pops wheelies)Now for the down side the red Cdi box was defective after some back and forth massaging the seller directly we decided on a 10$ refund.which is much better than the alternative of tearing it back down to do an exchange. That being said between my brothers and my buddies 15 people in all I'm the only one who's had any defective parts from this kit so it's safe to say it's a freak one off incident.Plus for the price of the kit 10$ is more than reasonable when you add up the value of Everythingit also give me the excuse to go deeper down the rabbit hole of performance mods lol time for an adjustable CDI