Brand new engine LOCKED UP

M

mechaniczman

New Member
I bought my first motorized bicycle kit from boygofast right off the bat I knew something wasnt right with the engine, it knocked terribly loud, it would randomly make loud hissing sounds like it was leaking compression but it wasnt it had at least 185 psi of compression, and i could seriously pedal faster than the engine could push me. But if I let it sit for a min and cranked it but up it would take off like a bat out of **** then bog right back down to 15 mph. I was taking it easy though to break it in good but then it started knocking loud and made the loud hissing sound again and locked up! and my back tire started sliding. I pedalled as fast as I could and jumped and landed on the seat to put pressure on the back tire and popped the clutch at the same time and the back tire just slid. I emailed the guy I got it from and told him what happened, hopefully he will send me another one.

What do you guys think about this? I know the casting is cheap and but are the internals of these engine really that crappy?
 
some of them are crappy, some of them are less crappy.

i blew a brand new one up on a 6 block trip to the store. the big end rod needlebearing blew apart and shrapneled inside the motor.

other motors i've had lasted over 10,000 miles.

hopefully BGF takes care of you.
 
So I went outside and took the head off and it all looked good I pedalled down the street and popped the clutch with the head off and it turned right over but still seemed way too stiff I cant even turn it over by standing on the pedal with the back tire off the ground with the head off.
 
yah i also tried adjusting the flower nut behind the flywheel cover to adjust the clutch but that didnt make a difference.

Also are you supposed to run 87 octane or 93 in these engines?
 
Ive been emailing the guy with boygofast and I really wish these chinesians knew how to speak engish, and they obviously dont know anything about engines i told him the engine he sent me was locked up he is telling me to check the conection for my kill switch wtf!
 
mechaniczman said:
yah i also tried adjusting the flower nut behind the flywheel cover to adjust the clutch but that didnt make a difference.

Also are you supposed to run 87 octane or 93 in these engines?
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How much oil did you add to the gas?
What ratio were you running and what kind of oil?

The gas grade wouldn't make it lock up and you only need to use low
octane gas in these low compression engines.
 
I did 25.1 rato to start out. I used penzoil non synthetic 2 stroke oil.
And low compression? This thing showed 185 psi with my dads seriously leaking old psi guage that i used to shoot with my BB gun. Thats higher than ive ever seen that gauge go.

It also had 2 headgaskets on it, I think to lower the compression ratio.
 
With the head off the motor should turn over super easy... Unless there is something you're not seeing causing friction between your cylinder and piston I would say you had a bearing in the bottom end die on you. As to why? Probably just a crappy part or something was poorly assembled.
The manuals suggest break-in mix should be 16:1, most people say that's way too much oil. I usually run a first gallon of 20:1, second gallon 24:1 (which should take you a couple hundred miles), and then move to 32:1 from then on. That said, I'm pretty sure your 25:1 mix should provide enough lubrication, but during the first 100 miles I tend to run just a little bit more oil because the parts in these motors can start out pretty dry and that extra oil in the first gallon helps get the oil where it needs to be faster.
 
Yah I went out to the shed and figured i would have a little fun with this bicycle engine, I tore it down cylinder and all and i put all my force onto the back tire while trying to roll the bike and the crankshaft would not move, I put it all back together and after a few mins of jamming the back wheel back and forth I got the engine freed up. (I was determined to get one last ride out of this engine before boygofast HOPEfuly sends me my new replacement)

I got it to start and it would go but it would lock back up after about 30 seconds, I eventually freed it up so many times that it would start right up and I rode if for probly an hour but my god it was knocking and vbrating so bad it sounded like I left the 10mm socket on top of the piston when I put the head back on.

I GAVE THAT BRAND NEW ENGINE HECK!!!!! it only had maybe 15 mins of run time on it before it locked up the first time! I was taking it off road, pulling in the clutch and revving it to the max just trying to throw a rod, eventually it died and wouldnt restart ill go out there later once it cools down it might start up again
 
I've given up on BGF and LEB engines. All 4 of mine were crap. Next time get a Flying Horse. They've proven to be a lot better quality.

A friend of mine just got a new Power King motor from BikeBerry, that looks pretty good, but we haven't started it yet, so I can't really vouch for good it is
 
Thanks, ill keep that in mind, btw bgf is going to be sending me a new engine, once I send the old one back. Hopefully this one will last longer than a day, hopefully get a few 1000 miles out of it, I want to grease everything inside of the engine before I crank it up, i have done some reasearch on it but It wasnt very clear and im not too familiar with these engines.

could someone tell me the best way to grease up the most valuable internal bearings of the engine?
 
You can grease up the transmission bearings by removing the clutch cable perch from atop of the transmission shaft housing and forcing grease inside the housing cavity. If you get too much in there it will come oozing out both ends, around the shaft bearings.

The quickest way to ruin the crankshaft bearings is to get any grease in or on them what so ever. The bearings are lubricated by the pre-mix oil that you mix with the gas to create the fuel.
Common axle grease does not mix or dissolve with oil. It actually will stay stuck in the bearings and prevent the fresh cooling and lubricating oil from getting to the critical parts of the bearings, thusly ruining them.
This is why there are products marketed for engine assembly called assembly lube. It is like a grease only it does mix and dissolve with oil. If you can somehow get assembly lube in to the bearings without tearing down the engine, it might help out for the first few seconds during the engine's very first start. After that it's job is done and the pre-mix oil comes into play.
 
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mechaniczman said:
Thanks, ill keep that in mind, btw bgf is going to be sending me a new engine, once I send the old one back. Hopefully this one will last longer than a day, hopefully get a few 1000 miles out of it, I want to grease everything inside of the engine before I crank it up, i have done some reasearch on it but It wasnt very clear and im not too familiar with these engines.

could someone tell me the best way to grease up the most valuable internal bearings of the engine?
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The biggest problem with their engines is with the crankshafts. They're all out of true, and out of balance. All 4 of mine were terrible. 2 motors lasted about 600 miles, and one 1000. The fourth motor I took apart out of the box for inspection. The crank was so bad I never bothered to put it back together.

Good luck with you new one.
 
I have purchased 4 engines from BGF as well. The first bike I built..I ordered a black Z280. I probably had around 600 miles on it when I sold the bike. It ran real good and was running good the day I sold it. The engine I have on my current bike that I ordered from BGF is a Z80 that is claimed to have "high quality" main bearings. Don't know if that is true or not, but with about 300 miles on it....it is running great and has power to spare. The other two engines are engines I ordered to use to build a couple bikes for friends. One friend I ordered a black X80 from LEB(same as BGF) and it is probably the smoothest engine, but is also the slowest which I beleive is do to an overly restrictive exaust. He was happy with the way it is...so I didn't mess with trying a different exaust or modifying the one he had, but it is a good runner regardless.....just not a race winner. The fourth engine I ordered was another Z280 in silver from BGF. This engine I just mounted on the bike a few weeks ago and it only has probably 25 miles on it. It seems to have a much less restrictive exaust then the X80 my other buuddy has, but it does have some clutch noise that don't sound real good...so probably going to have to dig into that one and see whats happening there. Other then that noise...it runs pretty good for an engine that is just starting its break-in and is running rich.

So my experience with BGF has been pretty positive as far as the items I have bought from him. I have never had to contact him for any type of customer service..so don't know how he is in that regards, but the 4 engines I have ordered have been as expected. I think alot of these engines are just luck of the draw. A half dozen or more different China factories build these engines and I would imagine that some are doing it better then others. My guess is that some of these engine sellers get there engines from more then one factory and the your odds of getting a good or bad engine just depend on what factories container they pull your engine kit from.

So if you are looking to get the best price possible...then you take the gamble that they pull your engine out of the right pile of scrap. So far I have been pretty lucky, but I also understand that by taking that risk...the next engine I order could be total crap. So if a guy wants to avoid taking as big of a gamble, a guy can pay a bit more to seller who claims to have inspected your engine before it gets shipped to make sure that you are recieving one that appears to be ok, but since these all come out of china...they are all sort of a gamble.

Now if you can find a seller who tears the engines down and replaces the inferior bearings with high quality bearings and inspects all the interior and its moving parts for defects...then you probably stand a good chance of getting a fine engine. However...that kind of attention to details is going to cost you and if you are mechanicly inclined, you are plenty capable of tearing down one of these engines yourself and going thru them properly before running.
 
mechaniczman said:
yup thats what im guna do, tear it down and grease it up before I ever run it.
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What I usually do is pump grease into the transmission shaft cavity, through the hole where the clutch cable stay screws in.

For the main bearings, I pour 2 stroke oil into the crankcase.
 
For 90 bucks for a replacement 66cc engine (including shipping), BGF has the best price. The closes thing I've found is livefast's which I have on my bike right now (I have a bgf and livefast that I swap if something breaks on one engine while I fix it).

The livefast is much better quality, but the BGF is about 40 bucks cheaper I believe. I recommend you buy a box of 10 replacement 6202 bearings and replace everything from bgf on arrival bearing wise. I've had all four bearings go bad in the first 800 miles on my bgf engine.

Here's a link to the bearings.
http://www.amazon.com/gp/product/B002BBI93G/ref=oh_details_o06_s00_i00
 
OP, I don't believe you'll get a new engine from Rick S. Please don't hold your breath. I've been waiting 4 years from him making good on a defective product and I've been banned from buying from him now.
 
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