Valve lash coming loose every 5-10 miles? Are you sure they are coming loose? Sounds more like the cam and/or lifters are starting to wear at an accelerated rate. If the lash adjuster jam nuts are tight an the gap keeps opening up, this would be the real issue, in my experience. Generally speaking, as long as the cam and lifters don't wear most valve lash gaps shrink over time due to the valve face wearing into the seat and the seat being worn down along with it to some degree.
If I had to guess, you have been running that engine with a modern 4 cycle oil that has very low zinc levels, and the HuaSheng 53cc uses a single lobe cam with solid tappet cam followers that actuate the pushrods. Since this is a solid tappet cam system you need to run a zinc additive, or an oil with a high level of zinc in it like Rotella T4 or T6, otherwise you will experience accelerated cam and tappet wear - a sign of which is constantly widening valve lash gaps.
On the plus side, if that is the case, a new cam setup with almost every part you need is $20.
144F-1G 53cc 4 stroke engine Parts set: #69. Lifters (2) #70. Push Rods (2) #71. Cam gear #73. Bearing
www.grubee.net
As far as the Electric bike vs. gas.
I finally got my first e-bike after 10 years of running 2 strokes. I want to qualify my position on the premise that I am speaking from a broadly "legal" point of view, which is not going to take local/state laws into consideration, but as a whole applies to most of the country. That means I am going to compare 50cc 2 or 4 stroke gas engines to a 750W e-bike.
A legal e-bike has a top speed of 20mph on throttle only operation, but is allowed to go faster with pedal assist. A top speed of a typical 750W e-bike with an unlocked Pedal Assist mode will see between 25-30mph in the highest assist mode, which matches the capability of most 50cc gas bike kits (both 2 and 4 stroke). What you sacrifice with the e-bike is either cost, or range. My bike has a 20ah battery, but can only manage maybe 30 miles in PAS5 on throttle only, and I can maintain about 25mph if I pedal assist in PAS4 or 5, and maybe extend that range 5-10 miles (Large me, large bike, and large fat tires). Once that battery is drained I am looking at a 6-8 hour charge time.
Now, if I put it in PAS2 or PAS3, I can peddle assist and maintain 15-20mph with a range of approximately 45-55 miles. It's the greatest compromise of speed and range, but does mean I have to pedal. It's not a ton of work mind you, and is good for your cardio health, but still requires more effort and still eventually needs that long charge time.
You can get batteries that come with fast chargers, which reduce that charge time to just a couple of hours, but those chargers also put more strain in the cells in the battery which reduces the lifespan of said battery. Good batteries are not cheap, some of them cost more than my last gas bike build, which was not a budget build either.
The cost difference for a good bike with a bigger battery is also double to triple that of most typical gas bike builds using quality parts, and just like any cheap bike on the market, the cheaper bikes out there - including those in the $1000-1500 range - tend to have the same budget parts and construction that require upgrading, work, or attention/adjustments that need to be kept on top of just like with every bike.
For $1000-1500 I could invest into Gemini Wheels to avoid most of the wheel problems, and use a quality/durable steel frame. The transmission issues are going to be more difficult to resolve, but some of that will come down to the quality of the transmission. What transmission are you using?
Then there is the biggest advantage of the gas bikes - greater range and no waiting to recharge.
