What are the problems with cheapo ebay engines?

T

TheEwaffle

New Member
Hi guys! I have considered getting an MB (however i'm really just considering because they are illegal in sweden) and I was wondering, whats the big downside with the "Ebay special" kits?
 
Welcome to the forum. I hope we can help you.

The downside is usually poor after-sale support. Many of the ebay sellers are simply drop shippers that won't be any help if you have problems with your engine after you get it. They typically don't offer or honor any warranty.

This is why we suggest buying from a reputable vendor who will stand behind the product they sell and will be there to answer questions if you need it. Generally the prices aren't that much higher when buying from a known and dependable source.

Of course that's also why we're here; to answer questions and offer you all of the assistance you might need to build a successful motorized bicycle.

Good luck.

Tom
 
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I've built all of my motorbikes with the cheapy 80cc kits on eBay. The downsides, I've noticed are that you can't ride them when it's wet or the magneto coil will crap out. The side cover where the clutch arm goes needs to be modified to fit the chain. Also, they are poorly manufactured so expect some pretty good noise, vibration, and harshness.

I'd definitely say it's worth it. Just plan on fixing things from time to time. Kind of like a British sports car.
 
The cheap magnetos are kinda like a Lucas electrical system ---- great analogy with the British 'sports' car!!
 
Just don't let the 'smoke' leak out. It is a well known fact that all electrical things are powered by smoke. The evidence is in the fact that if the smoke leaks out, they stop working.

Tom
 
2door said:
Just don't let the 'smoke' leak out. It is a well known fact that all electrical things are powered by smoke. The evidence is in the fact that if the smoke leaks out, they stop working.

Tom
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Tom, you can be my lawyer anytime!!laff
 
I had very good luck with my EBay engine. Other members had bad luck. it usually involved the kit being damaged in shipping and the seller providing no response or assistance.
 
I've had both good and bad luck with ebay specials... My first engine was nothing but trouble from the start, shook so hard it would barely get past 20mph, then after doing some upgrades to the jug, piston, added a fred head, and a few other goodies I was able to break the 30 barrier but it quickly lost compression and was shaking to death the whole time. Got a Dax bottom end and put all the good stuff on it like the ported jug, Fred head, CNS carb, and modified dirtbike pipe, broke it in again and it was hitting 39mph consistantly. I didn't like the CNS carb at all so I took it off in favor of a regular NT carb then I was surprised I was still hitting the same speeds, After the second tank was almost done I felt the bike become a little quicker and stronger so I checked the speed again and it was hitting 41 every run and 42 occasionally thru the NT carb and still using the 44 tooth rear sprocket with very little vibration, just barely becomes noticeable at higher speeds.
What I'm crediting for the added performance and better speeds is definitely the lack of vibration a good engine has over an ebay special that may or may not be balanced. I've used ebay engines on customer's bikes to do quick repairs on and they've lasted pretty good but it's always a roll of the dice if the engine will run smooth or not. On a customer's bike where they just want to put along under 30 it's not even an issue most the time, but if I get a customer that wants to do 40 or more then I have to spend the extra money on a Dax engine and set it up so it can reach those speeds just by adding a better pipe and maybe a smaller sprocket.
So basically for me, if the customer has no intentions of going over 25 and will barely ever go up to 30mph, the ebay engines will usually do, but if they want a faster bike, then I need to buy the better engines and parts so it won't shake to death or get too hot.
 
Typical, the real challenge is getting one to work well enough to say hey can;t believe the thing works that well. I've been looking at the alternatives and I've concluded that with the out of the box engine needs a titanium slug the cast aluminum piston weights to much, I cut one up out of raw stoke along with a wrist pin and run it without rings @ a few thousandths less the cylinder bore.
This setup will likely work well enough to forgive the thing for being less that a two thousand dollar engine and I'll tell you that not what can do to attempt a few corrections on the cheap kit engine.....
 
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the chinese 2-stroke kits are OK, and the newer kits with machined cranks are rather nice

the buyer needs to put some work into making the one-size-fits-all kit actually fit well on the bike he's building, and apply some common sense toward getting a dependable chain run to the rear wheel

any effort to get greater speed will give disappointing results

any tendency to run the bike at or close to maximum speed for extended periods will give disappointing results

failure to perform periodic, basic maintenance will give disappointing results

that said, I like them, I ride them, and I recommend them for folks with the temperament to handle them properly
 
2door said:
Just curious about your experience and what you're basing this opinion on. How many motorized bicycles have you built and what engines did you use?

Tom
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I havent built any successfully, but i had exerience with them. First a 400 dollar chinese atv that burned oil, hard starting, and did not start after a year of riding. The second is a brand new sears pocketbike also chinese. I bypassed the 23 MPH governor and went 45 MPH down hil and like 35 on flat ground. It overheated and ran hot so many times that the motor started clacking internally and lost all compression. Chinese made engines are garbage. I never had any problem with a briggs lawnmower. It overheated once, but ran again after 10 minutes of waiting and started after a few rips of the cord
 
All I can say is take the governor off that Briggs, run it at twice the rpm, then see what happens. Also, I believe that the Predator motors that are on a lot of the small generators are also made in China.
 
All china girls are chinese, the thing that matters is if you have an engine from a factory in china that has some quality control or a vendor like dax who assembles the engines and stands behind his products.
 
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