Quite a few if you take care of it,,and prepare the kit for use,here is a little list I came up with that will help.
Motorized Bicycle Riding Tips and Tricks
These motorized bike kits are manufactured in China with no or very little quality control.They are not very reliable out of the box,but steps can be taken for your new kit so it will last longer and give you much less trouble in the long run.
1.Make sure all your nuts and bolts are snug before riding,do not over tighten or you could destroy the hardware, hardware can always be upgraded to better quality like grade 8 head bolt studs,motor mounts and sprocket bolts.Take tools with you.
2.Let your engine warm up a minute before riding,,and make sure to use the proper gas/oil mix.16:1 first break in tank,then 32:1 second tank,there after 40:1 will work great,but 32:1 can be used if you feel like you need a little more oil for a richer tune.The factory recommends staying at 20:1 but that's just way too much oil for a 2 stroke and your wallet,,its solely up to you though.
3.Ride the bike under normal cruising conditions,don’t ride around wide open throttle everywhere,,THE MOTOR WILL NOT LAST LONG!!!
I would say you will be able to tell where the sweet spot is,,some bikes cruise 20-25 MPH nicely with no excessive vibration,all are different according to the sprocket gear ratio.
4.Make sure to pedal the bike up to speed so the clutch does not do all the work,,if you start out from a dead stop using the clutch all the time,,it will burn out the plate's and friction pads.
5.DO NOT RACE THE ENGINE DOWN HILL@HIGH RPM's,,if you are going down a large hill just take it easy,most Chinese motors will blow wrist pin bearings if over revved.If you want to coast pull clutch in on hills that’s cool otherwise just use the breaks and your own judgment keeping the bike at a normal cruising speed rpm.Going up hill it is fine to use wide open throttle.
6.Make sure to do periodic maintenance on the bike and kit.The wheel bearings need to be greased and checked once in a while along with tires and brakes.The chain tensioner needs to be checked for wear and kept tight as it could take a dive into the spokes if it comes loose.The chain should have 3/4”of slack in it and be oiled.The primary gears under the right side cover need to be greased with a pea sized dab of high temp grease once in a while.Dont over do the grease as the clutch could slip.
There are a lot of bikes with 10k miles on them,following these tips will help you.
Thats just the tip of the iceberg,get your thinkerin tinkerin prepared for its best...lol